]> git.sesse.net Git - nageru/blobdiff - nageru/mixer.cpp
Stop using the deprecated srt_socket().
[nageru] / nageru / mixer.cpp
index 367094cfeb08c35af2a9dfb9fdd1c5a0ae2d4892..01f6abede373918a723629b9ccc0d379cd6911bc 100644 (file)
@@ -4,6 +4,7 @@
 
 #include <assert.h>
 #include <epoxy/egl.h>
+#include <movit/effect.h>
 #include <movit/effect_chain.h>
 #include <movit/effect_util.h>
 #include <movit/flat_input.h>
 #include "shared/context.h"
 #include "decklink_capture.h"
 #include "decklink_output.h"
+#include "decklink_util.h"
 #include "defs.h"
 #include "shared/disk_space_estimator.h"
 #include "ffmpeg_capture.h"
 #include "flags.h"
+#include "image_input.h"
 #include "input_mapping.h"
 #include "shared/metrics.h"
+#include "shared/va_display.h"
 #include "mjpeg_encoder.h"
 #include "pbo_frame_allocator.h"
 #include "shared/ref_counted_gl_sync.h"
 #include "shared/timebase.h"
 #include "timecode_renderer.h"
 #include "v210_converter.h"
-#include "va_display_with_cleanup.h"
 #include "video_encoder.h"
 
 #undef Status
 #include <google/protobuf/util/json_util.h>
 #include "json.pb.h"
 
+#ifdef HAVE_SRT
+// Must come after CEF, since it includes <syslog.h>, which has #defines
+// that conflict with CEF logging constants.
+#include <srt/srt.h>
+#endif
+
 class IDeckLink;
 class QOpenGLContext;
 
@@ -108,11 +117,17 @@ void ensure_texture_resolution(PBOFrameAllocator::Userdata *userdata, unsigned f
                assert(false);
        }
 
-       if (first ||
-           width != userdata->last_width[field] ||
-           height != userdata->last_height[field] ||
-           cbcr_width != userdata->last_cbcr_width[field] ||
-           cbcr_height != userdata->last_cbcr_height[field]) {
+       const bool recreate_main_texture =
+               first ||
+               width != userdata->last_width[field] ||
+               height != userdata->last_height[field] ||
+               cbcr_width != userdata->last_cbcr_width[field] ||
+               cbcr_height != userdata->last_cbcr_height[field];
+       const bool recreate_v210_texture =
+               global_flags.ten_bit_input &&
+               (first || v210_width != userdata->last_v210_width[field] || height != userdata->last_height[field]);
+
+       if (recreate_main_texture) {
                // We changed resolution since last use of this texture, so we need to create
                // a new object. Note that this each card has its own PBOFrameAllocator,
                // we don't need to worry about these flip-flopping between resolutions.
@@ -152,11 +167,8 @@ void ensure_texture_resolution(PBOFrameAllocator::Userdata *userdata, unsigned f
                case PixelFormat_8BitBGRA:
                        glBindTexture(GL_TEXTURE_2D, userdata->tex_rgba[field]);
                        check_error();
-                       if (global_flags.can_disable_srgb_decoder) {  // See the comments in tweaked_inputs.h.
-                               glTexImage2D(GL_TEXTURE_2D, 0, GL_SRGB8_ALPHA8, width, height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, nullptr);
-                       } else {
-                               glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, nullptr);
-                       }
+                       // NOTE: sRGB may be disabled by sRGBSwitchingFlatInput.
+                       glTexImage2D(GL_TEXTURE_2D, 0, GL_SRGB8_ALPHA8, width, height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, nullptr);
                        check_error();
                        break;
                default:
@@ -167,14 +179,14 @@ void ensure_texture_resolution(PBOFrameAllocator::Userdata *userdata, unsigned f
                userdata->last_cbcr_width[field] = cbcr_width;
                userdata->last_cbcr_height[field] = cbcr_height;
        }
-       if (global_flags.ten_bit_input &&
-           (first || v210_width != userdata->last_v210_width[field])) {
+       if (recreate_v210_texture) {
                // Same as above; we need to recreate the texture.
                glBindTexture(GL_TEXTURE_2D, userdata->tex_v210[field]);
                check_error();
                glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB10_A2, v210_width, height, 0, GL_RGBA, GL_UNSIGNED_INT_2_10_10_10_REV, nullptr);
                check_error();
                userdata->last_v210_width[field] = v210_width;
+               userdata->last_height[field] = height;
        }
 }
 
@@ -301,21 +313,22 @@ void QueueLengthPolicy::update_policy(steady_clock::time_point now,
        metric_input_queue_safe_length_frames = safe_queue_length;
 }
 
-Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
+Mixer::Mixer(const QSurfaceFormat &format)
        : httpd(),
-         num_cards(num_cards),
          mixer_surface(create_surface(format)),
          h264_encoder_surface(create_surface(format)),
-         decklink_output_surface(create_surface(format))
+         decklink_output_surface(create_surface(format)),
+         image_update_surface(create_surface(format))
 {
        memcpy(ycbcr_interpretation, global_flags.ycbcr_interpretation, sizeof(ycbcr_interpretation));
        CHECK(init_movit(MOVIT_SHADER_DIR, MOVIT_DEBUG_OFF));
        check_error();
 
-       // This nearly always should be true.
-       global_flags.can_disable_srgb_decoder =
-               epoxy_has_gl_extension("GL_EXT_texture_sRGB_decode") &&
-               epoxy_has_gl_extension("GL_ARB_sampler_objects");
+       if (!epoxy_has_gl_extension("GL_EXT_texture_sRGB_decode") ||
+           !epoxy_has_gl_extension("GL_ARB_sampler_objects")) {
+               fprintf(stderr, "Nageru requires GL_EXT_texture_sRGB_decode and GL_ARB_sampler_objects to run.\n");
+               exit(1);
+       }
 
        // Since we allow non-bouncing 4:2:2 YCbCrInputs, effective subpixel precision
        // will be halved when sampling them, and we need to compensate here.
@@ -347,6 +360,11 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        ycbcr_format.cb_y_position = 0.5f;
        ycbcr_format.cr_y_position = 0.5f;
 
+       // Initialize the neutral colors to sane values.
+       for (unsigned i = 0; i < MAX_VIDEO_CARDS; ++i) {
+               last_received_neutral_color[i] = RGBTriplet(1.0f, 1.0f, 1.0f);
+       }
+
        // Display chain; shows the live output produced by the main chain (or rather, a copy of it).
        display_chain.reset(new EffectChain(global_flags.width, global_flags.height, resource_pool.get()));
        check_error();
@@ -363,17 +381,17 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        }
 
        // Must be instantiated after VideoEncoder has initialized global_flags.use_zerocopy.
-       theme.reset(new Theme(global_flags.theme_filename, global_flags.theme_dirs, resource_pool.get(), num_cards));
+       theme.reset(new Theme(global_flags.theme_filename, global_flags.theme_dirs, resource_pool.get()));
 
        // Must be instantiated after the theme, as the theme decides the number of FFmpeg inputs.
        std::vector<FFmpegCapture *> video_inputs = theme->get_video_inputs();
-       audio_mixer.reset(new AudioMixer(num_cards, video_inputs.size()));
+       audio_mixer.reset(new AudioMixer);
 
        httpd.add_endpoint("/channels", bind(&Mixer::get_channels_json, this), HTTPD::ALLOW_ALL_ORIGINS);
-       for (int channel_idx = 2; channel_idx < theme->get_num_channels(); ++channel_idx) {
+       for (int channel_idx = 0; channel_idx < theme->get_num_channels(); ++channel_idx) {
                char url[256];
-               snprintf(url, sizeof(url), "/channels/%d/color", channel_idx);
-               httpd.add_endpoint(url, bind(&Mixer::get_channel_color_http, this, unsigned(channel_idx)), HTTPD::ALLOW_ALL_ORIGINS);
+               snprintf(url, sizeof(url), "/channels/%d/color", channel_idx + 2);
+               httpd.add_endpoint(url, bind(&Mixer::get_channel_color_http, this, unsigned(channel_idx + 2)), HTTPD::ALLOW_ALL_ORIGINS);
        }
 
        // Start listening for clients only once VideoEncoder has written its header, if any.
@@ -387,19 +405,25 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        {
                IDeckLinkIterator *decklink_iterator = CreateDeckLinkIteratorInstance();
                if (decklink_iterator != nullptr) {
-                       for ( ; card_index < num_cards; ++card_index) {
+                       for ( ; card_index < unsigned(global_flags.max_num_cards); ++card_index) {
                                IDeckLink *decklink;
                                if (decklink_iterator->Next(&decklink) != S_OK) {
                                        break;
                                }
 
+                               if (!decklink_card_is_active(decklink, card_index)) {
+                                       fprintf(stderr, "DeckLink card %u is inactive in current profile, skipping (try changing it in Desktop Video Setup)\n", card_index);
+                                       decklink->Release();
+                                       continue;
+                               }
+
                                DeckLinkCapture *capture = new DeckLinkCapture(decklink, card_index);
                                DeckLinkOutput *output = new DeckLinkOutput(resource_pool.get(), decklink_output_surface, global_flags.width, global_flags.height, card_index);
                                if (!output->set_device(decklink)) {
                                        delete output;
                                        output = nullptr;
                                }
-                               configure_card(card_index, capture, CardType::LIVE_CARD, output);
+                               configure_card(card_index, capture, CardType::LIVE_CARD, output, /*is_srt_card=*/false);
                                ++num_pci_devices;
                        }
                        decklink_iterator->Release();
@@ -410,31 +434,44 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        }
 
        unsigned num_usb_devices = BMUSBCapture::num_cards();
-       for (unsigned usb_card_index = 0; usb_card_index < num_usb_devices && card_index < num_cards; ++usb_card_index, ++card_index) {
+       for (unsigned usb_card_index = 0; usb_card_index < num_usb_devices && card_index < unsigned(global_flags.max_num_cards); ++usb_card_index, ++card_index) {
                BMUSBCapture *capture = new BMUSBCapture(usb_card_index);
                capture->set_card_disconnected_callback(bind(&Mixer::bm_hotplug_remove, this, card_index));
-               configure_card(card_index, capture, CardType::LIVE_CARD, /*output=*/nullptr);
+               configure_card(card_index, capture, CardType::LIVE_CARD, /*output=*/nullptr, /*is_srt_card=*/false);
        }
        fprintf(stderr, "Found %u USB card(s).\n", num_usb_devices);
 
+       // Fill up with fake cards for as long as we can, so that the FFmpeg
+       // and HTML cards always come last.
        unsigned num_fake_cards = 0;
-       for ( ; card_index < num_cards; ++card_index, ++num_fake_cards) {
-               FakeCapture *capture = new FakeCapture(global_flags.width, global_flags.height, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
-               configure_card(card_index, capture, CardType::FAKE_CAPTURE, /*output=*/nullptr);
+#ifdef HAVE_CEF
+       size_t num_html_inputs = theme->get_html_inputs().size();
+#else
+       size_t num_html_inputs = 0;
+#endif
+       for ( ; card_index < MAX_VIDEO_CARDS - video_inputs.size() - num_html_inputs; ++card_index) {
+               // Only bother to activate fake capture cards to satisfy the minimum.
+               bool is_active = card_index < unsigned(global_flags.min_num_cards) || cards[card_index].force_active;
+               if (is_active) {
+                       FakeCapture *capture = new FakeCapture(global_flags.width, global_flags.height, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
+                       configure_card(card_index, capture, CardType::FAKE_CAPTURE, /*output=*/nullptr, /*is_srt_card=*/false);
+                       ++num_fake_cards;
+               } else {
+                       configure_card(card_index, nullptr, CardType::FAKE_CAPTURE, /*output=*/nullptr, /*is_srt_card=*/false);
+               }
        }
 
        if (num_fake_cards > 0) {
                fprintf(stderr, "Initialized %u fake cards.\n", num_fake_cards);
        }
 
-       // Initialize all video inputs the theme asked for. Note that these are
-       // all put _after_ the regular cards, which stop at <num_cards> - 1.
+       // Initialize all video inputs the theme asked for.
        for (unsigned video_card_index = 0; video_card_index < video_inputs.size(); ++card_index, ++video_card_index) {
                if (card_index >= MAX_VIDEO_CARDS) {
                        fprintf(stderr, "ERROR: Not enough card slots available for the videos the theme requested.\n");
-                       exit(1);
+                       abort();
                }
-               configure_card(card_index, video_inputs[video_card_index], CardType::FFMPEG_INPUT, /*output=*/nullptr);
+               configure_card(card_index, video_inputs[video_card_index], CardType::FFMPEG_INPUT, /*output=*/nullptr, /*is_srt_card=*/false);
                video_inputs[video_card_index]->set_card_index(card_index);
        }
        num_video_inputs = video_inputs.size();
@@ -445,9 +482,9 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        for (unsigned html_card_index = 0; html_card_index < html_inputs.size(); ++card_index, ++html_card_index) {
                if (card_index >= MAX_VIDEO_CARDS) {
                        fprintf(stderr, "ERROR: Not enough card slots available for the HTML inputs the theme requested.\n");
-                       exit(1);
+                       abort();
                }
-               configure_card(card_index, html_inputs[html_card_index], CardType::CEF_INPUT, /*output=*/nullptr);
+               configure_card(card_index, html_inputs[html_card_index], CardType::CEF_INPUT, /*output=*/nullptr, /*is_srt_card=*/false);
                html_inputs[html_card_index]->set_card_index(card_index);
        }
        num_html_inputs = html_inputs.size();
@@ -456,9 +493,11 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        BMUSBCapture::set_card_connected_callback(bind(&Mixer::bm_hotplug_add, this, _1));
        BMUSBCapture::start_bm_thread();
 
-       for (unsigned card_index = 0; card_index < num_cards + num_video_inputs + num_html_inputs; ++card_index) {
-               cards[card_index].queue_length_policy.reset(card_index);
+#ifdef HAVE_SRT
+       if (global_flags.srt_port >= 0) {
+               start_srt();
        }
+#endif
 
        chroma_subsampler.reset(new ChromaSubsampler(resource_pool.get()));
 
@@ -466,7 +505,7 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
                if (!v210Converter::has_hardware_support()) {
                        fprintf(stderr, "ERROR: --ten-bit-input requires support for OpenGL compute shaders\n");
                        fprintf(stderr, "       (OpenGL 4.3, or GL_ARB_compute_shader + GL_ARB_shader_image_load_store).\n");
-                       exit(1);
+                       abort();
                }
                v210_converter.reset(new v210Converter());
 
@@ -483,7 +522,7 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
                if (!v210Converter::has_hardware_support()) {
                        fprintf(stderr, "ERROR: --ten-bit-output requires support for OpenGL compute shaders\n");
                        fprintf(stderr, "       (OpenGL 4.3, or GL_ARB_compute_shader + GL_ARB_shader_image_load_store).\n");
-                       exit(1);
+                       abort();
                }
        }
 
@@ -500,18 +539,24 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        }
 
        output_jitter_history.register_metrics({{ "card", "output" }});
+
+       ImageInput::start_update_thread(image_update_surface);
 }
 
 Mixer::~Mixer()
 {
+       ImageInput::end_update_thread();
+
        if (mjpeg_encoder != nullptr) {
                mjpeg_encoder->stop();
        }
        httpd.stop();
        BMUSBCapture::stop_bm_thread();
 
-       for (unsigned card_index = 0; card_index < num_cards + num_video_inputs + num_html_inputs; ++card_index) {
-               cards[card_index].capture->stop_dequeue_thread();
+       for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
+               if (cards[card_index].capture != nullptr) {  // Active.
+                       cards[card_index].capture->stop_dequeue_thread();
+               }
                if (cards[card_index].output) {
                        cards[card_index].output->end_output();
                        cards[card_index].output.reset();
@@ -521,16 +566,26 @@ Mixer::~Mixer()
        video_encoder.reset(nullptr);
 }
 
-void Mixer::configure_card(unsigned card_index, CaptureInterface *capture, CardType card_type, DeckLinkOutput *output)
+void Mixer::configure_card(unsigned card_index, CaptureInterface *capture, CardType card_type, DeckLinkOutput *output, bool is_srt_card)
 {
-       printf("Configuring card %d...\n", card_index);
+       bool is_active = capture != nullptr;
+       if (is_active) {
+               printf("Configuring card %d...\n", card_index);
+       } else {
+               assert(card_type == CardType::FAKE_CAPTURE);
+       }
 
        CaptureCard *card = &cards[card_index];
        if (card->capture != nullptr) {
+               card_mutex.unlock();  // The dequeue thread could be waiting for bm_frame().
                card->capture->stop_dequeue_thread();
+               card_mutex.lock();
        }
        card->capture.reset(capture);
        card->is_fake_capture = (card_type == CardType::FAKE_CAPTURE);
+       if (card->is_fake_capture) {
+               card->fake_capture_counter = fake_capture_counter++;
+       }
        card->is_cef_capture = (card_type == CardType::CEF_INPUT);
        card->may_have_dropped_last_frame = false;
        card->type = card_type;
@@ -549,29 +604,47 @@ void Mixer::configure_card(unsigned card_index, CaptureInterface *capture, CardT
                pixel_format = PixelFormat_8BitYCbCr;
        }
 
-       card->capture->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
-       if (card->frame_allocator == nullptr) {
-               card->frame_allocator.reset(new PBOFrameAllocator(pixel_format, 8 << 20, global_flags.width, global_flags.height));  // 8 MB.
-       }
-       card->capture->set_video_frame_allocator(card->frame_allocator.get());
-       if (card->surface == nullptr) {
-               card->surface = create_surface_with_same_format(mixer_surface);
+       if (is_active) {
+               card->capture->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
+               if (card->frame_allocator == nullptr) {
+                       card->frame_allocator.reset(new PBOFrameAllocator(pixel_format, 8 << 20, global_flags.width, global_flags.height, card_index, mjpeg_encoder.get()));  // 8 MB.
+               } else {
+                       // The format could have changed, but we cannot reset the allocator
+                       // and create a new one from scratch, since there may be allocated
+                       // frames from it that expect to call release_frame() on it.
+                       // Instead, ask the allocator to create new frames for us and discard
+                       // any old ones as they come back. This takes the mutex while
+                       // allocating, but nothing should really be sending frames in there
+                       // right now anyway (start_bm_capture() has not been called yet).
+                       card->frame_allocator->reconfigure(pixel_format, 8 << 20, global_flags.width, global_flags.height, card_index, mjpeg_encoder.get());
+               }
+               card->capture->set_video_frame_allocator(card->frame_allocator.get());
+               if (card->surface == nullptr) {
+                       card->surface = create_surface_with_same_format(mixer_surface);
+               }
+               while (!card->new_frames.empty()) card->new_frames.pop_front();
+               card->last_timecode = -1;
+               card->capture->set_pixel_format(pixel_format);
+               card->capture->configure_card();
+
+               // NOTE: start_bm_capture() happens in thread_func().
        }
-       while (!card->new_frames.empty()) card->new_frames.pop_front();
-       card->last_timecode = -1;
-       card->capture->set_pixel_format(pixel_format);
-       card->capture->configure_card();
 
-       // NOTE: start_bm_capture() happens in thread_func().
+       if (is_srt_card) {
+               assert(card_type == CardType::FFMPEG_INPUT);
+       }
 
-       DeviceSpec device;
-       if (card_type == CardType::FFMPEG_INPUT) {
-               device = DeviceSpec{InputSourceType::FFMPEG_VIDEO_INPUT, card_index - num_cards};
+       DeviceSpec device{InputSourceType::CAPTURE_CARD, card_index};
+       unsigned num_channels = card_type == CardType::LIVE_CARD ? 8 : 2;
+       if (is_active) {
+               audio_mixer->set_device_parameters(device, card->capture->get_description(), card_type, num_channels, /*active=*/true);
        } else {
-               device = DeviceSpec{InputSourceType::CAPTURE_CARD, card_index};
+               // Note: Keeps the previous name, if any.
+               char name[32];
+               snprintf(name, sizeof(name), "Fake card %u", card_index + 1);
+               audio_mixer->set_device_parameters(device, name, card_type, num_channels, /*active=*/false);
        }
        audio_mixer->reset_resampler(device);
-       audio_mixer->set_display_name(device, card->capture->get_description());
        audio_mixer->trigger_state_changed_callback();
 
        // Unregister old metrics, if any.
@@ -579,63 +652,204 @@ void Mixer::configure_card(unsigned card_index, CaptureInterface *capture, CardT
                const vector<pair<string, string>> &labels = card->labels;
                card->jitter_history.unregister_metrics(labels);
                card->queue_length_policy.unregister_metrics(labels);
-               global_metrics.remove("input_received_frames", labels);
-               global_metrics.remove("input_dropped_frames_jitter", labels);
-               global_metrics.remove("input_dropped_frames_error", labels);
-               global_metrics.remove("input_dropped_frames_resets", labels);
-               global_metrics.remove("input_queue_length_frames", labels);
-               global_metrics.remove("input_queue_duped_frames", labels);
-
-               global_metrics.remove("input_has_signal_bool", labels);
-               global_metrics.remove("input_is_connected_bool", labels);
-               global_metrics.remove("input_interlaced_bool", labels);
-               global_metrics.remove("input_width_pixels", labels);
-               global_metrics.remove("input_height_pixels", labels);
-               global_metrics.remove("input_frame_rate_nom", labels);
-               global_metrics.remove("input_frame_rate_den", labels);
-               global_metrics.remove("input_sample_rate_hz", labels);
-       }
-
-       // Register metrics.
-       vector<pair<string, string>> labels;
-       char card_name[64];
-       snprintf(card_name, sizeof(card_name), "%d", card_index);
-       labels.emplace_back("card", card_name);
-
-       switch (card_type) {
-       case CardType::LIVE_CARD:
-               labels.emplace_back("cardtype", "live");
-               break;
-       case CardType::FAKE_CAPTURE:
-               labels.emplace_back("cardtype", "fake");
-               break;
-       case CardType::FFMPEG_INPUT:
-               labels.emplace_back("cardtype", "ffmpeg");
-               break;
-       case CardType::CEF_INPUT:
-               labels.emplace_back("cardtype", "cef");
-               break;
-       default:
-               assert(false);
+               global_metrics.remove_if_exists("input_received_frames", labels);
+               global_metrics.remove_if_exists("input_dropped_frames_jitter", labels);
+               global_metrics.remove_if_exists("input_dropped_frames_error", labels);
+               global_metrics.remove_if_exists("input_dropped_frames_resets", labels);
+               global_metrics.remove_if_exists("input_queue_length_frames", labels);
+               global_metrics.remove_if_exists("input_queue_duped_frames", labels);
+
+               global_metrics.remove_if_exists("input_has_signal_bool", labels);
+               global_metrics.remove_if_exists("input_is_connected_bool", labels);
+               global_metrics.remove_if_exists("input_interlaced_bool", labels);
+               global_metrics.remove_if_exists("input_width_pixels", labels);
+               global_metrics.remove_if_exists("input_height_pixels", labels);
+               global_metrics.remove_if_exists("input_frame_rate_nom", labels);
+               global_metrics.remove_if_exists("input_frame_rate_den", labels);
+               global_metrics.remove_if_exists("input_sample_rate_hz", labels);
+
+               // SRT metrics.
+
+               // Global measurements (counters).
+               global_metrics.remove_if_exists("srt_uptime_seconds", labels);
+               global_metrics.remove_if_exists("srt_send_duration_seconds", labels);
+               global_metrics.remove_if_exists("srt_sent_bytes", labels);
+               global_metrics.remove_if_exists("srt_received_bytes", labels);
+
+               vector<pair<string, string>> packet_labels = card->labels;
+               packet_labels.emplace_back("type", "normal");
+               global_metrics.remove_if_exists("srt_sent_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_received_packets", packet_labels);
+
+               packet_labels.back().second = "lost";
+               global_metrics.remove_if_exists("srt_sent_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_received_packets", packet_labels);
+
+               packet_labels.back().second = "retransmitted";
+               global_metrics.remove_if_exists("srt_sent_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_sent_bytes", packet_labels);
+
+               packet_labels.back().second = "ack";
+               global_metrics.remove_if_exists("srt_sent_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_received_packets", packet_labels);
+
+               packet_labels.back().second = "nak";
+               global_metrics.remove_if_exists("srt_sent_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_received_packets", packet_labels);
+
+               packet_labels.back().second = "dropped";
+               global_metrics.remove_if_exists("srt_sent_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_received_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_sent_bytes", packet_labels);
+               global_metrics.remove_if_exists("srt_received_bytes", packet_labels);
+
+               packet_labels.back().second = "undecryptable";
+               global_metrics.remove_if_exists("srt_received_packets", packet_labels);
+               global_metrics.remove_if_exists("srt_received_bytes", packet_labels);
+
+               global_metrics.remove_if_exists("srt_filter_sent_extra_packets", labels);
+               global_metrics.remove_if_exists("srt_filter_received_extra_packets", labels);
+               global_metrics.remove_if_exists("srt_filter_received_rebuilt_packets", labels);
+               global_metrics.remove_if_exists("srt_filter_received_lost_packets", labels);
+
+               // Instant measurements (gauges).
+               global_metrics.remove_if_exists("srt_packet_sending_period_seconds", labels);
+               global_metrics.remove_if_exists("srt_flow_window_packets", labels);
+               global_metrics.remove_if_exists("srt_congestion_window_packets", labels);
+               global_metrics.remove_if_exists("srt_flight_size_packets", labels);
+               global_metrics.remove_if_exists("srt_rtt_seconds", labels);
+               global_metrics.remove_if_exists("srt_estimated_bandwidth_bits_per_second", labels);
+               global_metrics.remove_if_exists("srt_bandwidth_ceiling_bits_per_second", labels);
+               global_metrics.remove_if_exists("srt_send_buffer_available_bytes", labels);
+               global_metrics.remove_if_exists("srt_receive_buffer_available_bytes", labels);
+               global_metrics.remove_if_exists("srt_mss_bytes", labels);
+
+               global_metrics.remove_if_exists("srt_sender_unacked_packets", labels);
+               global_metrics.remove_if_exists("srt_sender_unacked_bytes", labels);
+               global_metrics.remove_if_exists("srt_sender_unacked_timespan_seconds", labels);
+               global_metrics.remove_if_exists("srt_sender_delivery_delay_seconds", labels);
+
+               global_metrics.remove_if_exists("srt_receiver_unacked_packets", labels);
+               global_metrics.remove_if_exists("srt_receiver_unacked_bytes", labels);
+               global_metrics.remove_if_exists("srt_receiver_unacked_timespan_seconds", labels);
+               global_metrics.remove_if_exists("srt_receiver_delivery_delay_seconds", labels);
+       }
+
+       if (is_active) {
+               // Register metrics.
+               vector<pair<string, string>> labels;
+               char card_name[64];
+               snprintf(card_name, sizeof(card_name), "%d", card_index);
+               labels.emplace_back("card", card_name);
+
+               switch (card_type) {
+               case CardType::LIVE_CARD:
+                       labels.emplace_back("cardtype", "live");
+                       break;
+               case CardType::FAKE_CAPTURE:
+                       labels.emplace_back("cardtype", "fake");
+                       break;
+               case CardType::FFMPEG_INPUT:
+                       if (is_srt_card) {
+                               labels.emplace_back("cardtype", "srt");
+                       } else {
+                               labels.emplace_back("cardtype", "ffmpeg");
+                       }
+                       break;
+               case CardType::CEF_INPUT:
+                       labels.emplace_back("cardtype", "cef");
+                       break;
+               default:
+                       assert(false);
+               }
+               card->jitter_history.register_metrics(labels);
+               card->queue_length_policy.register_metrics(labels);
+               global_metrics.add("input_received_frames", labels, &card->metric_input_received_frames);
+               global_metrics.add("input_dropped_frames_jitter", labels, &card->metric_input_dropped_frames_jitter);
+               global_metrics.add("input_dropped_frames_error", labels, &card->metric_input_dropped_frames_error);
+               global_metrics.add("input_dropped_frames_resets", labels, &card->metric_input_resets);
+               global_metrics.add("input_queue_length_frames", labels, &card->metric_input_queue_length_frames, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_queue_duped_frames", labels, &card->metric_input_duped_frames);
+
+               global_metrics.add("input_has_signal_bool", labels, &card->metric_input_has_signal_bool, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_is_connected_bool", labels, &card->metric_input_is_connected_bool, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_interlaced_bool", labels, &card->metric_input_interlaced_bool, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_width_pixels", labels, &card->metric_input_width_pixels, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_height_pixels", labels, &card->metric_input_height_pixels, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_frame_rate_nom", labels, &card->metric_input_frame_rate_nom, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_frame_rate_den", labels, &card->metric_input_frame_rate_den, Metrics::TYPE_GAUGE);
+               global_metrics.add("input_sample_rate_hz", labels, &card->metric_input_sample_rate_hz, Metrics::TYPE_GAUGE);
+
+               if (is_srt_card) {
+                       // Global measurements (counters).
+                       global_metrics.add("srt_uptime_seconds", labels, &card->metric_srt_uptime_seconds);
+                       global_metrics.add("srt_send_duration_seconds", labels, &card->metric_srt_send_duration_seconds);
+                       global_metrics.add("srt_sent_bytes", labels, &card->metric_srt_sent_bytes);
+                       global_metrics.add("srt_received_bytes", labels, &card->metric_srt_received_bytes);
+
+                       vector<pair<string, string>> packet_labels = labels;
+                       packet_labels.emplace_back("type", "normal");
+                       global_metrics.add("srt_sent_packets", packet_labels, &card->metric_srt_sent_packets_normal);
+                       global_metrics.add("srt_received_packets", packet_labels, &card->metric_srt_received_packets_normal);
+
+                       packet_labels.back().second = "lost";
+                       global_metrics.add("srt_sent_packets", packet_labels, &card->metric_srt_sent_packets_lost);
+                       global_metrics.add("srt_received_packets", packet_labels, &card->metric_srt_received_packets_lost);
+
+                       packet_labels.back().second = "retransmitted";
+                       global_metrics.add("srt_sent_packets", packet_labels, &card->metric_srt_sent_packets_retransmitted);
+                       global_metrics.add("srt_sent_bytes", packet_labels, &card->metric_srt_sent_bytes_retransmitted);
+
+                       packet_labels.back().second = "ack";
+                       global_metrics.add("srt_sent_packets", packet_labels, &card->metric_srt_sent_packets_ack);
+                       global_metrics.add("srt_received_packets", packet_labels, &card->metric_srt_received_packets_ack);
+
+                       packet_labels.back().second = "nak";
+                       global_metrics.add("srt_sent_packets", packet_labels, &card->metric_srt_sent_packets_nak);
+                       global_metrics.add("srt_received_packets", packet_labels, &card->metric_srt_received_packets_nak);
+
+                       packet_labels.back().second = "dropped";
+                       global_metrics.add("srt_sent_packets", packet_labels, &card->metric_srt_sent_packets_dropped);
+                       global_metrics.add("srt_received_packets", packet_labels, &card->metric_srt_received_packets_dropped);
+                       global_metrics.add("srt_sent_bytes", packet_labels, &card->metric_srt_sent_bytes_dropped);
+                       global_metrics.add("srt_received_bytes", packet_labels, &card->metric_srt_received_bytes_dropped);
+
+                       packet_labels.back().second = "undecryptable";
+                       global_metrics.add("srt_received_packets", packet_labels, &card->metric_srt_received_packets_undecryptable);
+                       global_metrics.add("srt_received_bytes", packet_labels, &card->metric_srt_received_bytes_undecryptable);
+
+                       global_metrics.add("srt_filter_sent_extra_packets", labels, &card->metric_srt_filter_sent_packets);
+                       global_metrics.add("srt_filter_received_extra_packets", labels, &card->metric_srt_filter_received_extra_packets);
+                       global_metrics.add("srt_filter_received_rebuilt_packets", labels, &card->metric_srt_filter_received_rebuilt_packets);
+                       global_metrics.add("srt_filter_received_lost_packets", labels, &card->metric_srt_filter_received_lost_packets);
+
+                       // Instant measurements (gauges).
+                       global_metrics.add("srt_packet_sending_period_seconds", labels, &card->metric_srt_packet_sending_period_seconds, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_flow_window_packets", labels, &card->metric_srt_flow_window_packets, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_congestion_window_packets", labels, &card->metric_srt_congestion_window_packets, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_flight_size_packets", labels, &card->metric_srt_flight_size_packets, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_rtt_seconds", labels, &card->metric_srt_rtt_seconds, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_estimated_bandwidth_bits_per_second", labels, &card->metric_srt_estimated_bandwidth_bits_per_second, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_bandwidth_ceiling_bits_per_second", labels, &card->metric_srt_bandwidth_ceiling_bits_per_second, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_send_buffer_available_bytes", labels, &card->metric_srt_send_buffer_available_bytes, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_receive_buffer_available_bytes", labels, &card->metric_srt_receive_buffer_available_bytes, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_mss_bytes", labels, &card->metric_srt_mss_bytes, Metrics::TYPE_GAUGE);
+
+                       global_metrics.add("srt_sender_unacked_packets", labels, &card->metric_srt_sender_unacked_packets, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_sender_unacked_bytes", labels, &card->metric_srt_sender_unacked_bytes, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_sender_unacked_timespan_seconds", labels, &card->metric_srt_sender_unacked_timespan_seconds, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_sender_delivery_delay_seconds", labels, &card->metric_srt_sender_delivery_delay_seconds, Metrics::TYPE_GAUGE);
+
+                       global_metrics.add("srt_receiver_unacked_packets", labels, &card->metric_srt_receiver_unacked_packets, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_receiver_unacked_bytes", labels, &card->metric_srt_receiver_unacked_bytes, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_receiver_unacked_timespan_seconds", labels, &card->metric_srt_receiver_unacked_timespan_seconds, Metrics::TYPE_GAUGE);
+                       global_metrics.add("srt_receiver_delivery_delay_seconds", labels, &card->metric_srt_receiver_delivery_delay_seconds, Metrics::TYPE_GAUGE);
+               }
+
+               card->labels = labels;
+       } else {
+               card->labels.clear();
        }
-       card->jitter_history.register_metrics(labels);
-       card->queue_length_policy.register_metrics(labels);
-       global_metrics.add("input_received_frames", labels, &card->metric_input_received_frames);
-       global_metrics.add("input_dropped_frames_jitter", labels, &card->metric_input_dropped_frames_jitter);
-       global_metrics.add("input_dropped_frames_error", labels, &card->metric_input_dropped_frames_error);
-       global_metrics.add("input_dropped_frames_resets", labels, &card->metric_input_resets);
-       global_metrics.add("input_queue_length_frames", labels, &card->metric_input_queue_length_frames, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_queue_duped_frames", labels, &card->metric_input_duped_frames);
-
-       global_metrics.add("input_has_signal_bool", labels, &card->metric_input_has_signal_bool, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_is_connected_bool", labels, &card->metric_input_is_connected_bool, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_interlaced_bool", labels, &card->metric_input_interlaced_bool, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_width_pixels", labels, &card->metric_input_width_pixels, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_height_pixels", labels, &card->metric_input_height_pixels, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_frame_rate_nom", labels, &card->metric_input_frame_rate_nom, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_frame_rate_den", labels, &card->metric_input_frame_rate_den, Metrics::TYPE_GAUGE);
-       global_metrics.add("input_sample_rate_hz", labels, &card->metric_input_sample_rate_hz, Metrics::TYPE_GAUGE);
-       card->labels = labels;
 }
 
 void Mixer::set_output_card_internal(int card_index)
@@ -671,8 +885,8 @@ void Mixer::set_output_card_internal(int card_index)
                lock.lock();
                card->parked_capture = move(card->capture);
                CaptureInterface *fake_capture = new FakeCapture(global_flags.width, global_flags.height, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
-               configure_card(card_index, fake_capture, CardType::FAKE_CAPTURE, card->output.release());
-               card->queue_length_policy.reset(card_index);
+               configure_card(card_index, fake_capture, CardType::FAKE_CAPTURE, card->output.release(), /*is_srt_card=*/false);
+               card->jitter_history.clear();
                card->capture->start_bm_capture();
                desired_output_video_mode = output_video_mode = card->output->pick_video_mode(desired_output_video_mode);
                card->output->start_output(desired_output_video_mode, pts_int);
@@ -693,22 +907,13 @@ int unwrap_timecode(uint16_t current_wrapped, int last)
        }
 }
 
-DeviceSpec card_index_to_device(unsigned card_index, unsigned num_cards)
-{
-       if (card_index >= num_cards) {
-               return DeviceSpec{InputSourceType::FFMPEG_VIDEO_INPUT, card_index - num_cards};
-       } else {
-               return DeviceSpec{InputSourceType::CAPTURE_CARD, card_index};
-       }
-}
-
 }  // namespace
 
 void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                      FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
                     FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)
 {
-       DeviceSpec device = card_index_to_device(card_index, num_cards);
+       DeviceSpec device{InputSourceType::CAPTURE_CARD, card_index};
        CaptureCard *card = &cards[card_index];
 
        ++card->metric_input_received_frames;
@@ -745,7 +950,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        size_t num_samples = (audio_frame.len > audio_offset) ? (audio_frame.len - audio_offset) / audio_format.num_channels / (audio_format.bits_per_sample / 8) : 0;
        if (num_samples > OUTPUT_FREQUENCY / 10 && card->type != CardType::FFMPEG_INPUT) {
                printf("%s: Dropping frame with implausible audio length (len=%d, offset=%d) [timecode=0x%04x video_len=%d video_offset=%d video_format=%x)\n",
-                       spec_to_string(device).c_str(), int(audio_frame.len), int(audio_offset),
+                       description_for_card(card_index).c_str(), int(audio_frame.len), int(audio_offset),
                        timecode, int(video_frame.len), int(video_offset), video_format.id);
                if (video_frame.owner) {
                        video_frame.owner->release_frame(video_frame);
@@ -767,14 +972,14 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
        if (dropped_frames > MAX_FPS * 2) {
                fprintf(stderr, "%s lost more than two seconds (or time code jumping around; from 0x%04x to 0x%04x), resetting resampler\n",
-                       spec_to_string(device).c_str(), card->last_timecode, timecode);
+                       description_for_card(card_index).c_str(), card->last_timecode, timecode);
                audio_mixer->reset_resampler(device);
                dropped_frames = 0;
                ++card->metric_input_resets;
        } else if (dropped_frames > 0) {
                // Insert silence as needed.
                fprintf(stderr, "%s dropped %d frame(s) (before timecode 0x%04x), inserting silence.\n",
-                       spec_to_string(device).c_str(), dropped_frames, timecode);
+                       description_for_card(card_index).c_str(), dropped_frames, timecode);
                card->metric_input_dropped_frames_error += dropped_frames;
 
                bool success;
@@ -785,6 +990,35 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
        if (num_samples > 0) {
                audio_mixer->add_audio(device, audio_frame.data + audio_offset, num_samples, audio_format, audio_frame.received_timestamp);
+
+               // Audio for the MJPEG stream. We don't resample; audio that's not in 48 kHz
+               // just gets dropped for now.
+               //
+               // Only bother doing MJPEG encoding if there are any connected clients
+               // that want the stream.
+               if (httpd.get_num_connected_multicam_clients() > 0 ||
+                   httpd.get_num_connected_siphon_clients(card_index) > 0) {
+                       vector<int32_t> converted_samples = convert_audio_to_fixed32(audio_frame.data + audio_offset, num_samples, audio_format, 2);
+                       lock_guard<mutex> lock(card_mutex);
+                       if (card->new_raw_audio.empty()) {
+                               card->new_raw_audio = move(converted_samples);
+                       } else {
+                               // For raw audio, we don't really synchronize audio and video;
+                               // we just put the audio in frame by frame, and if a video frame is
+                               // dropped, we still keep the audio, which means it will be added
+                               // to the beginning of the next frame. It would probably be better
+                               // to move the audio pts earlier to show this, but most players can
+                               // live with some jitter, and in a lot of ways, it's much nicer for
+                               // Futatabi to have all audio locked to a video frame.
+                               card->new_raw_audio.insert(card->new_raw_audio.end(), converted_samples.begin(), converted_samples.end());
+
+                               // Truncate to one second, just to be sure we don't have infinite buildup in case of weirdness.
+                               if (card->new_raw_audio.size() > OUTPUT_FREQUENCY * 2) {
+                                       size_t excess_samples = card->new_raw_audio.size() - OUTPUT_FREQUENCY * 2;
+                                       card->new_raw_audio.erase(card->new_raw_audio.begin(), card->new_raw_audio.begin() + excess_samples);
+                               }
+                       }
+               }
        }
 
        // Done with the audio, so release it.
@@ -795,13 +1029,21 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        card->last_timecode = timecode;
 
        PBOFrameAllocator::Userdata *userdata = (PBOFrameAllocator::Userdata *)video_frame.userdata;
-       if (card->type == CardType::FFMPEG_INPUT) {
+       if (card->type == CardType::FFMPEG_INPUT && userdata != nullptr) {
                FFmpegCapture *ffmpeg_capture = static_cast<FFmpegCapture *>(card->capture.get());
                userdata->has_last_subtitle = ffmpeg_capture->get_has_last_subtitle();
                userdata->last_subtitle = ffmpeg_capture->get_last_subtitle();
        }
+#ifdef HAVE_SRT
+       if (card->type == CardType::FFMPEG_INPUT) {
+               int srt_sock = static_cast<FFmpegCapture *>(card->capture.get())->get_srt_sock();
+               if (srt_sock != -1) {
+                       update_srt_stats(srt_sock, card);
+               }
+       }
+#endif
 
-       size_t cbcr_width, cbcr_height, cbcr_offset, y_offset;
+       size_t y_offset, cbcr_offset;
        size_t expected_length = video_format.stride * (video_format.height + video_format.extra_lines_top + video_format.extra_lines_bottom);
        if (userdata != nullptr && userdata->pixel_format == PixelFormat_8BitYCbCrPlanar) {
                // The calculation above is wrong for planar Y'CbCr, so just override it.
@@ -810,22 +1052,18 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                expected_length = video_frame.len;
 
                userdata->ycbcr_format = (static_cast<FFmpegCapture *>(card->capture.get()))->get_current_frame_ycbcr_format();
-               cbcr_width = video_format.width / userdata->ycbcr_format.chroma_subsampling_x;
-               cbcr_height = video_format.height / userdata->ycbcr_format.chroma_subsampling_y;
-               cbcr_offset = video_format.width * video_format.height;
                y_offset = 0;
+               cbcr_offset = video_format.width * video_format.height;
        } else {
                // All the other Y'CbCr formats are 4:2:2.
-               cbcr_width = video_format.width / 2;
-               cbcr_height = video_format.height;
-               cbcr_offset = video_offset / 2;
                y_offset = video_frame.size / 2 + video_offset / 2;
+               cbcr_offset = video_offset / 2;
        }
        if (video_frame.len - video_offset == 0 ||
            video_frame.len - video_offset != expected_length) {
                if (video_frame.len != 0) {
-                       printf("%s: Dropping video frame with wrong length (%ld; expected %ld)\n",
-                               spec_to_string(device).c_str(), video_frame.len - video_offset, expected_length);
+                       printf("%s: Dropping video frame with wrong length (%zu; expected %zu)\n",
+                               description_for_card(card_index).c_str(), video_frame.len - video_offset, expected_length);
                }
                if (video_frame.owner) {
                        video_frame.owner->release_frame(video_frame);
@@ -850,19 +1088,14 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
        unsigned num_fields = video_format.interlaced ? 2 : 1;
        steady_clock::time_point frame_upload_start;
-       bool interlaced_stride = false;
        if (video_format.interlaced) {
                // Send the two fields along as separate frames; the other side will need to add
                // a deinterlacer to actually get this right.
                assert(video_format.height % 2 == 0);
                video_format.height /= 2;
-               cbcr_height /= 2;
                assert(frame_length % 2 == 0);
                frame_length /= 2;
                num_fields = 2;
-               if (video_format.second_field_start == 1) {
-                       interlaced_stride = true;
-               }
                frame_upload_start = steady_clock::now();
        }
        assert(userdata != nullptr);
@@ -873,79 +1106,15 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        userdata->last_frame_rate_den = video_format.frame_rate_den;
        RefCountedFrame frame(video_frame);
 
-       // Upload the textures.
+       // Send the frames on to the main thread, which will upload and process htem.
+       // It is entirely possible to upload them in the same thread (and it might even be
+       // faster, depending on the GPU and driver), but it appears to be trickling
+       // driver bugs very easily.
+       //
+       // Note that this means we must hold on to the actual frame data in <userdata>
+       // until the upload is done, but we hold on to <frame> much longer than that
+       // (in fact, all the way until we no longer use the texture in rendering).
        for (unsigned field = 0; field < num_fields; ++field) {
-               // Put the actual texture upload in a lambda that is executed in the main thread.
-               // It is entirely possible to do this in the same thread (and it might even be
-               // faster, depending on the GPU and driver), but it appears to be trickling
-               // driver bugs very easily.
-               //
-               // Note that this means we must hold on to the actual frame data in <userdata>
-               // until the upload command is run, but we hold on to <frame> much longer than that
-               // (in fact, all the way until we no longer use the texture in rendering).
-               auto upload_func = [this, field, video_format, y_offset, video_offset, cbcr_offset, cbcr_width, cbcr_height, interlaced_stride, userdata]() {
-                       unsigned field_start_line;
-                       if (field == 1) {
-                               field_start_line = video_format.second_field_start;
-                       } else {
-                               field_start_line = video_format.extra_lines_top;
-                       }
-
-                       // For anything not FRAME_FORMAT_YCBCR_10BIT, v210_width will be nonsensical but not used.
-                       size_t v210_width = video_format.stride / sizeof(uint32_t);
-                       ensure_texture_resolution(userdata, field, video_format.width, video_format.height, cbcr_width, cbcr_height, v210_width);
-
-                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, userdata->pbo);
-                       check_error();
-
-                       switch (userdata->pixel_format) {
-                       case PixelFormat_10BitYCbCr: {
-                               size_t field_start = video_offset + video_format.stride * field_start_line;
-                               upload_texture(userdata->tex_v210[field], v210_width, video_format.height, video_format.stride, interlaced_stride, GL_RGBA, GL_UNSIGNED_INT_2_10_10_10_REV, field_start);
-                               v210_converter->convert(userdata->tex_v210[field], userdata->tex_444[field], video_format.width, video_format.height);
-                               break;
-                       }
-                       case PixelFormat_8BitYCbCr: {
-                               size_t field_y_start = y_offset + video_format.width * field_start_line;
-                               size_t field_cbcr_start = cbcr_offset + cbcr_width * field_start_line * sizeof(uint16_t);
-
-                               // Make up our own strides, since we are interleaving.
-                               upload_texture(userdata->tex_y[field], video_format.width, video_format.height, video_format.width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_y_start);
-                               upload_texture(userdata->tex_cbcr[field], cbcr_width, cbcr_height, cbcr_width * sizeof(uint16_t), interlaced_stride, GL_RG, GL_UNSIGNED_BYTE, field_cbcr_start);
-                               break;
-                       }
-                       case PixelFormat_8BitYCbCrPlanar: {
-                               assert(field_start_line == 0);  // We don't really support interlaced here.
-                               size_t field_y_start = y_offset;
-                               size_t field_cb_start = cbcr_offset;
-                               size_t field_cr_start = cbcr_offset + cbcr_width * cbcr_height;
-
-                               // Make up our own strides, since we are interleaving.
-                               upload_texture(userdata->tex_y[field], video_format.width, video_format.height, video_format.width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_y_start);
-                               upload_texture(userdata->tex_cb[field], cbcr_width, cbcr_height, cbcr_width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_cb_start);
-                               upload_texture(userdata->tex_cr[field], cbcr_width, cbcr_height, cbcr_width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_cr_start);
-                               break;
-                       }
-                       case PixelFormat_8BitBGRA: {
-                               size_t field_start = video_offset + video_format.stride * field_start_line;
-                               upload_texture(userdata->tex_rgba[field], video_format.width, video_format.height, video_format.stride, interlaced_stride, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, field_start);
-                               // These could be asked to deliver mipmaps at any time.
-                               glBindTexture(GL_TEXTURE_2D, userdata->tex_rgba[field]);
-                               check_error();
-                               glGenerateMipmap(GL_TEXTURE_2D);
-                               check_error();
-                               glBindTexture(GL_TEXTURE_2D, 0);
-                               check_error();
-                               break;
-                       }
-                       default:
-                               assert(false);
-                       }
-
-                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
-                       check_error();
-               };
-
                if (field == 1) {
                        // Don't upload the second field as fast as we can; wait until
                        // the field time has approximately passed. (Otherwise, we could
@@ -965,12 +1134,17 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                        new_frame.length = frame_length;
                        new_frame.field = field;
                        new_frame.interlaced = video_format.interlaced;
-                       new_frame.upload_func = upload_func;
                        new_frame.dropped_frames = dropped_frames;
                        new_frame.received_timestamp = video_frame.received_timestamp;  // Ignore the audio timestamp.
                        new_frame.video_format = video_format;
+                       new_frame.video_offset = video_offset;
                        new_frame.y_offset = y_offset;
                        new_frame.cbcr_offset = cbcr_offset;
+                       new_frame.texture_uploaded = false;
+                       if (card->type == CardType::FFMPEG_INPUT) {
+                               FFmpegCapture *ffmpeg_capture = static_cast<FFmpegCapture *>(card->capture.get());
+                               new_frame.neutral_color = ffmpeg_capture->get_last_neutral_color();
+                       }
                        card->new_frames.push_back(move(new_frame));
                        card->jitter_history.frame_arrived(video_frame.received_timestamp, frame_length, dropped_frames);
                        card->may_have_dropped_last_frame = false;
@@ -979,6 +1153,87 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        }
 }
 
+void Mixer::upload_texture_for_frame(
+       int field, bmusb::VideoFormat video_format,
+       size_t y_offset, size_t cbcr_offset, size_t video_offset, PBOFrameAllocator::Userdata *userdata)
+{
+       size_t cbcr_width, cbcr_height;
+       if (userdata != nullptr && userdata->pixel_format == PixelFormat_8BitYCbCrPlanar) {
+               cbcr_width = video_format.width / userdata->ycbcr_format.chroma_subsampling_x;
+               cbcr_height = video_format.height / userdata->ycbcr_format.chroma_subsampling_y;
+       } else {
+               // All the other Y'CbCr formats are 4:2:2.
+               cbcr_width = video_format.width / 2;
+               cbcr_height = video_format.height;
+       }
+
+       bool interlaced_stride = video_format.interlaced && (video_format.second_field_start == 1);
+       if (video_format.interlaced) {
+               cbcr_height /= 2;
+       }
+
+       unsigned field_start_line;
+       if (field == 1) {
+               field_start_line = video_format.second_field_start;
+       } else {
+               field_start_line = video_format.extra_lines_top;
+       }
+
+       // For anything not FRAME_FORMAT_YCBCR_10BIT, v210_width will be nonsensical but not used.
+       size_t v210_width = video_format.stride / sizeof(uint32_t);
+       ensure_texture_resolution(userdata, field, video_format.width, video_format.height, cbcr_width, cbcr_height, v210_width);
+
+       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, userdata->pbo);
+       check_error();
+
+       switch (userdata->pixel_format) {
+               case PixelFormat_10BitYCbCr: {
+                       size_t field_start = video_offset + video_format.stride * field_start_line;
+                       upload_texture(userdata->tex_v210[field], v210_width, video_format.height, video_format.stride, interlaced_stride, GL_RGBA, GL_UNSIGNED_INT_2_10_10_10_REV, field_start);
+                       v210_converter->convert(userdata->tex_v210[field], userdata->tex_444[field], video_format.width, video_format.height);
+                       break;
+               }
+               case PixelFormat_8BitYCbCr: {
+                       size_t field_y_start = y_offset + video_format.width * field_start_line;
+                       size_t field_cbcr_start = cbcr_offset + cbcr_width * field_start_line * sizeof(uint16_t);
+
+                       // Make up our own strides, since we are interleaving.
+                       upload_texture(userdata->tex_y[field], video_format.width, video_format.height, video_format.width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_y_start);
+                       upload_texture(userdata->tex_cbcr[field], cbcr_width, cbcr_height, cbcr_width * sizeof(uint16_t), interlaced_stride, GL_RG, GL_UNSIGNED_BYTE, field_cbcr_start);
+                       break;
+               }
+               case PixelFormat_8BitYCbCrPlanar: {
+                       assert(field_start_line == 0);  // We don't really support interlaced here.
+                       size_t field_y_start = y_offset;
+                       size_t field_cb_start = cbcr_offset;
+                       size_t field_cr_start = cbcr_offset + cbcr_width * cbcr_height;
+
+                       // Make up our own strides, since we are interleaving.
+                       upload_texture(userdata->tex_y[field], video_format.width, video_format.height, video_format.width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_y_start);
+                       upload_texture(userdata->tex_cb[field], cbcr_width, cbcr_height, cbcr_width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_cb_start);
+                       upload_texture(userdata->tex_cr[field], cbcr_width, cbcr_height, cbcr_width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_cr_start);
+                       break;
+               }
+               case PixelFormat_8BitBGRA: {
+                       size_t field_start = video_offset + video_format.stride * field_start_line;
+                       upload_texture(userdata->tex_rgba[field], video_format.width, video_format.height, video_format.stride, interlaced_stride, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, field_start);
+                       // These could be asked to deliver mipmaps at any time.
+                       glBindTexture(GL_TEXTURE_2D, userdata->tex_rgba[field]);
+                       check_error();
+                       glGenerateMipmap(GL_TEXTURE_2D);
+                       check_error();
+                       glBindTexture(GL_TEXTURE_2D, 0);
+                       check_error();
+                       break;
+               }
+               default:
+                       assert(false);
+       }
+
+       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+       check_error();
+}
+
 void Mixer::bm_hotplug_add(libusb_device *dev)
 {
        lock_guard<mutex> lock(hotplug_mutex);
@@ -998,13 +1253,13 @@ void Mixer::thread_func()
        QOpenGLContext *context = create_context(mixer_surface);
        if (!make_current(context, mixer_surface)) {
                printf("oops\n");
-               exit(1);
+               abort();
        }
 
        // Start the actual capture. (We don't want to do it before we're actually ready
        // to process output frames.)
-       for (unsigned card_index = 0; card_index < num_cards + num_video_inputs + num_html_inputs; ++card_index) {
-               if (int(card_index) != output_card_index) {
+       for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
+               if (int(card_index) != output_card_index && cards[card_index].capture != nullptr) {
                        cards[card_index].capture->start_bm_capture();
                }
        }
@@ -1024,6 +1279,11 @@ void Mixer::thread_func()
                        output->start_output(desired_output_video_mode, pts_int);
                }
 
+               {
+                       lock_guard<mutex> lock(card_mutex);
+                       handle_hotplugged_cards();
+               }
+
                CaptureCard::NewFrame new_frames[MAX_VIDEO_CARDS];
                bool has_new_frame[MAX_VIDEO_CARDS] = { false };
 
@@ -1034,18 +1294,16 @@ void Mixer::thread_func()
                        master_card_index = output_card_index;
                } else {
                        master_card_is_output = false;
-                       master_card_index = theme->map_signal(master_clock_channel);
-                       assert(master_card_index < num_cards + num_video_inputs);
+                       master_card_index = theme->map_signal_to_card(master_clock_channel);
+                       assert(master_card_index < MAX_VIDEO_CARDS);
                }
 
-               OutputFrameInfo output_frame_info = get_one_frame_from_each_card(master_card_index, master_card_is_output, new_frames, has_new_frame);
+               vector<int32_t> raw_audio[MAX_VIDEO_CARDS];  // For MJPEG encoding.
+               OutputFrameInfo output_frame_info = get_one_frame_from_each_card(master_card_index, master_card_is_output, new_frames, has_new_frame, raw_audio);
                schedule_audio_resampling_tasks(output_frame_info.dropped_frames, output_frame_info.num_samples, output_frame_info.frame_duration, output_frame_info.is_preroll, output_frame_info.frame_timestamp);
                stats_dropped_frames += output_frame_info.dropped_frames;
 
-               handle_hotplugged_cards();
-
-               for (unsigned card_index = 0; card_index < num_cards + num_video_inputs + num_html_inputs; ++card_index) {
-                       DeviceSpec device = card_index_to_device(card_index, num_cards);
+               for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
                        if (card_index == master_card_index || !has_new_frame[card_index]) {
                                continue;
                        }
@@ -1054,19 +1312,21 @@ void Mixer::thread_func()
                        }
                        if (new_frames[card_index].dropped_frames > 0) {
                                printf("%s dropped %d frames before this\n",
-                                       spec_to_string(device).c_str(), int(new_frames[card_index].dropped_frames));
+                                       description_for_card(card_index).c_str(), int(new_frames[card_index].dropped_frames));
                        }
                }
 
                // If the first card is reporting a corrupted or otherwise dropped frame,
                // just increase the pts (skipping over this frame) and don't try to compute anything new.
-               if (!master_card_is_output && new_frames[master_card_index].frame->len == 0) {
+               if (!master_card_is_output &&
+                   new_frames[master_card_index].frame != nullptr &&  // Timeout.
+                   new_frames[master_card_index].frame->len == 0) {
                        ++stats_dropped_frames;
                        pts_int += new_frames[master_card_index].length;
                        continue;
                }
 
-               for (unsigned card_index = 0; card_index < num_cards + num_video_inputs + num_html_inputs; ++card_index) {
+               for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
                        if (!has_new_frame[card_index] || new_frames[card_index].frame->len == 0)
                                continue;
 
@@ -1076,19 +1336,30 @@ void Mixer::thread_func()
                        check_error();
 
                        // The new texture might need uploading before use.
-                       if (new_frame->upload_func) {
-                               new_frame->upload_func();
-                               new_frame->upload_func = nullptr;
+                       if (!new_frame->texture_uploaded) {
+                               upload_texture_for_frame(new_frame->field, new_frame->video_format, new_frame->y_offset, new_frame->cbcr_offset,
+                                       new_frame->video_offset, (PBOFrameAllocator::Userdata *)new_frame->frame->userdata);
+                               new_frame->texture_uploaded = true;
                        }
 
-                       // Only bother doing MJPEG encoding if there are any connected clients
-                       // that want the stream. FIXME: We should also stop memcpy-ing if there are none!
-                       if (httpd.get_num_connected_multicam_clients() > 0) {
-                               auto stream_it = global_flags.card_to_mjpeg_stream_export.find(card_index);
-                               if (stream_it != global_flags.card_to_mjpeg_stream_export.end()) {
-                                       mjpeg_encoder->upload_frame(pts_int, stream_it->second, new_frame->frame, new_frame->video_format, new_frame->y_offset, new_frame->cbcr_offset);
-                               }
+                       // Only set the white balance if it actually changed. This means that the user
+                       // is free to override the white balance in a video with no white balance information
+                       // actually set (ie. r=g=b=1 all the time), or one where the white point is wrong,
+                       // but frame-to-frame decisions will be heeded. We do this pretty much as late
+                       // as possible (ie., after picking out the frame from the buffer), so that we are sure
+                       // that the change takes effect on exactly the right frame.
+                       if (fabs(new_frame->neutral_color.r - last_received_neutral_color[card_index].r) > 1e-3 ||
+                           fabs(new_frame->neutral_color.g - last_received_neutral_color[card_index].g) > 1e-3 ||
+                           fabs(new_frame->neutral_color.b - last_received_neutral_color[card_index].b) > 1e-3) {
+                               theme->set_wb_for_card(card_index, new_frame->neutral_color.r, new_frame->neutral_color.g, new_frame->neutral_color.b);
+                               last_received_neutral_color[card_index] = new_frame->neutral_color;
+                       }
+
+                       if (new_frame->frame->data_copy != nullptr && mjpeg_encoder->should_encode_mjpeg_for_card(card_index)) {
+                               RGBTriplet neutral_color = theme->get_white_balance_for_card(card_index);
+                               mjpeg_encoder->upload_frame(pts_int, card_index, new_frame->frame, new_frame->video_format, new_frame->y_offset, new_frame->cbcr_offset, move(raw_audio[card_index]), neutral_color);
                        }
+
                }
 
                int64_t frame_duration = output_frame_info.frame_duration;
@@ -1184,11 +1455,11 @@ void Mixer::trim_queue(CaptureCard *card, size_t safe_queue_length)
 pair<string, string> Mixer::get_channels_json()
 {
        Channels ret;
-       for (int channel_idx = 2; channel_idx < theme->get_num_channels(); ++channel_idx) {
+       for (int channel_idx = 0; channel_idx < theme->get_num_channels(); ++channel_idx) {
                Channel *channel = ret.add_channel();
-               channel->set_index(channel_idx);
-               channel->set_name(theme->get_channel_name(channel_idx));
-               channel->set_color(theme->get_channel_color(channel_idx));
+               channel->set_index(channel_idx + 2);
+               channel->set_name(theme->get_channel_name(channel_idx + 2));
+               channel->set_color(theme->get_channel_color(channel_idx + 2));
        }
        string contents;
        google::protobuf::util::MessageToJsonString(ret, &contents);  // Ignore any errors.
@@ -1200,35 +1471,54 @@ pair<string, string> Mixer::get_channel_color_http(unsigned channel_idx)
        return make_pair(theme->get_channel_color(channel_idx), "text/plain");
 }
 
-Mixer::OutputFrameInfo Mixer::get_one_frame_from_each_card(unsigned master_card_index, bool master_card_is_output, CaptureCard::NewFrame new_frames[MAX_VIDEO_CARDS], bool has_new_frame[MAX_VIDEO_CARDS])
+Mixer::OutputFrameInfo Mixer::get_one_frame_from_each_card(unsigned master_card_index, bool master_card_is_output, CaptureCard::NewFrame new_frames[MAX_VIDEO_CARDS], bool has_new_frame[MAX_VIDEO_CARDS], vector<int32_t> raw_audio[MAX_VIDEO_CARDS])
 {
        OutputFrameInfo output_frame_info;
+       constexpr steady_clock::duration master_card_timeout = milliseconds(200);
 start:
        unique_lock<mutex> lock(card_mutex, defer_lock);
+       bool timed_out = false;
        if (master_card_is_output) {
                // Clocked to the output, so wait for it to be ready for the next frame.
                cards[master_card_index].output->wait_for_frame(pts_int, &output_frame_info.dropped_frames, &output_frame_info.frame_duration, &output_frame_info.is_preroll, &output_frame_info.frame_timestamp);
                lock.lock();
        } else {
                // Wait for the master card to have a new frame.
-               // TODO: Add a timeout.
                output_frame_info.is_preroll = false;
                lock.lock();
-               cards[master_card_index].new_frames_changed.wait(lock, [this, master_card_index]{ return !cards[master_card_index].new_frames.empty() || cards[master_card_index].capture->get_disconnected(); });
+               timed_out = !cards[master_card_index].new_frames_changed.wait_for(lock,
+                       master_card_timeout,
+                       [this, master_card_index] {
+                               return !cards[master_card_index].new_frames.empty() ||
+                                       cards[master_card_index].capture == nullptr ||
+                                       cards[master_card_index].capture->get_disconnected();
+                       });
+               if (timed_out) {
+                       fprintf(stderr, "WARNING: Master card (%s) did not deliver a frame for %u ms, creating a fake one.\n",
+                               description_for_card(master_card_index).c_str(),
+                               unsigned(duration_cast<milliseconds>(master_card_timeout).count()));
+               }
        }
 
-       if (master_card_is_output) {
+       if (timed_out) {
+               // The master card stalled for 200 ms (possible when it's e.g.
+               // an SRT card). Send a frame no matter what; this also makes sure
+               // any other cards get to empty their queues, and in general,
+               // that we make _some_ sort of forward progress.
+               handle_hotplugged_cards();
+       } else if (master_card_is_output) {
                handle_hotplugged_cards();
        } else if (cards[master_card_index].new_frames.empty()) {
                // We were woken up, but not due to a new frame. Deal with it
                // and then restart.
-               assert(cards[master_card_index].capture->get_disconnected());
+               assert(cards[master_card_index].capture == nullptr ||
+                      cards[master_card_index].capture->get_disconnected());
                handle_hotplugged_cards();
                lock.unlock();
                goto start;
        }
 
-       for (unsigned card_index = 0; card_index < num_cards + num_video_inputs + num_html_inputs; ++card_index) {
+       for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
                CaptureCard *card = &cards[card_index];
                if (card->new_frames.empty()) {  // Starvation.
                        ++card->metric_input_duped_frames;
@@ -1239,7 +1529,7 @@ start:
                                // we dropped. (may_have_dropped_last_frame is set whenever we
                                // trim the queue completely away, and cleared when we actually
                                // get a new frame.)
-                               ((CEFCapture *)card->capture.get())->request_new_frame();
+                               ((CEFCapture *)card->capture.get())->request_new_frame(/*ignore_if_locked=*/true);
                        }
 #endif
                } else {
@@ -1248,9 +1538,17 @@ start:
                        card->new_frames.pop_front();
                        card->new_frames_changed.notify_all();
                }
+
+               raw_audio[card_index] = move(card->new_raw_audio);
        }
 
-       if (!master_card_is_output) {
+       if (timed_out) {
+               // Pretend the frame happened a while ago and was only processed now,
+               // so that we get the duration sort-of right. This isn't ideal.
+               output_frame_info.dropped_frames = 0;  // Hard to define, really.
+               output_frame_info.frame_duration = lrint(TIMEBASE * duration<double>(master_card_timeout).count());
+               output_frame_info.frame_timestamp = steady_clock::now() - master_card_timeout;
+       } else if (!master_card_is_output) {
                output_frame_info.frame_timestamp = new_frames[master_card_index].received_timestamp;
                output_frame_info.dropped_frames = new_frames[master_card_index].dropped_frames;
                output_frame_info.frame_duration = new_frames[master_card_index].length;
@@ -1260,7 +1558,7 @@ start:
                output_jitter_history.frame_arrived(output_frame_info.frame_timestamp, output_frame_info.frame_duration, output_frame_info.dropped_frames);
        }
 
-       for (unsigned card_index = 0; card_index < num_cards + num_video_inputs + num_html_inputs; ++card_index) {
+       for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
                CaptureCard *card = &cards[card_index];
                if (has_new_frame[card_index] &&
                    !input_card_is_master_clock(card_index, master_card_index) &&
@@ -1279,45 +1577,82 @@ start:
 
        // This might get off by a fractional sample when changing master card
        // between ones with different frame rates, but that's fine.
-       int num_samples_times_timebase = OUTPUT_FREQUENCY * output_frame_info.frame_duration + fractional_samples;
+       int64_t num_samples_times_timebase = int64_t(OUTPUT_FREQUENCY) * output_frame_info.frame_duration + fractional_samples;
        output_frame_info.num_samples = num_samples_times_timebase / TIMEBASE;
        fractional_samples = num_samples_times_timebase % TIMEBASE;
        assert(output_frame_info.num_samples >= 0);
 
+       if (timed_out) {
+               DeviceSpec device{InputSourceType::CAPTURE_CARD, master_card_index};
+               bool success;
+               do {
+                       success = audio_mixer->add_silence(device, output_frame_info.num_samples, /*dropped_frames=*/0);
+               } while (!success);
+       }
+
        return output_frame_info;
 }
 
 void Mixer::handle_hotplugged_cards()
 {
        // Check for cards that have been disconnected since last frame.
-       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
+       for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
                CaptureCard *card = &cards[card_index];
-               if (card->capture->get_disconnected()) {
-                       fprintf(stderr, "Card %u went away, replacing with a fake card.\n", card_index);
-                       FakeCapture *capture = new FakeCapture(global_flags.width, global_flags.height, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
-                       configure_card(card_index, capture, CardType::FAKE_CAPTURE, /*output=*/nullptr);
-                       card->queue_length_policy.reset(card_index);
-                       card->capture->start_bm_capture();
+               if (card->capture != nullptr && card->capture->get_disconnected()) {
+                       bool is_active = card_index < unsigned(global_flags.min_num_cards) || cards[card_index].force_active;
+                       if (is_active) {
+                               fprintf(stderr, "Card %u went away, replacing with a fake card.\n", card_index);
+                               FakeCapture *capture = new FakeCapture(global_flags.width, global_flags.height, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
+                               configure_card(card_index, capture, CardType::FAKE_CAPTURE, /*output=*/nullptr, /*is_srt_card=*/false);
+                               card->jitter_history.clear();
+                               card->capture->start_bm_capture();
+                       } else {
+                               // NOTE: The theme might end up forcing the card back at some later point
+                               // (ie., force_active is false now, but might immediately be true again on
+                               // e.g. the next frame). That should be rare, though, so we don't bother
+                               // adjusting the message.
+                               fprintf(stderr, "Card %u went away, removing. (To keep a fake card, increase --num-cards.)\n", card_index);
+                               theme->remove_card(card_index);
+                               configure_card(card_index, /*capture=*/nullptr, CardType::FAKE_CAPTURE, /*output=*/nullptr, /*is_srt_card=*/false);
+                               card->jitter_history.clear();
+                       }
+               }
+       }
+
+       // Count how many active cards we already have. Used below to check that we
+       // don't go past the max_cards limit set by the user. Note that (non-SRT) video
+       // and HTML “cards” don't count towards this limit.
+       int num_video_cards = 0;
+       for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
+               CaptureCard *card = &cards[card_index];
+               if (card->type == CardType::LIVE_CARD || is_srt_card(card)) {
+                       ++num_video_cards;
                }
        }
 
        // Check for cards that have been connected since last frame.
        vector<libusb_device *> hotplugged_cards_copy;
+#ifdef HAVE_SRT
+       vector<int> hotplugged_srt_cards_copy;
+#endif
        {
                lock_guard<mutex> lock(hotplug_mutex);
                swap(hotplugged_cards, hotplugged_cards_copy);
+#ifdef HAVE_SRT
+               swap(hotplugged_srt_cards, hotplugged_srt_cards_copy);
+#endif
        }
        for (libusb_device *new_dev : hotplugged_cards_copy) {
                // Look for a fake capture card where we can stick this in.
                int free_card_index = -1;
-               for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
+               for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
                        if (cards[card_index].is_fake_capture) {
                                free_card_index = card_index;
                                break;
                        }
                }
 
-               if (free_card_index == -1) {
+               if (free_card_index == -1 || num_video_cards >= global_flags.max_num_cards) {
                        fprintf(stderr, "New card plugged in, but no free slots -- ignoring.\n");
                        libusb_unref_device(new_dev);
                } else {
@@ -1325,19 +1660,86 @@ void Mixer::handle_hotplugged_cards()
                        fprintf(stderr, "New card plugged in, choosing slot %d.\n", free_card_index);
                        CaptureCard *card = &cards[free_card_index];
                        BMUSBCapture *capture = new BMUSBCapture(free_card_index, new_dev);
-                       configure_card(free_card_index, capture, CardType::LIVE_CARD, /*output=*/nullptr);
-                       card->queue_length_policy.reset(free_card_index);
+                       configure_card(free_card_index, capture, CardType::LIVE_CARD, /*output=*/nullptr, /*is_srt_card=*/false);
+                       card->jitter_history.clear();
                        capture->set_card_disconnected_callback(bind(&Mixer::bm_hotplug_remove, this, free_card_index));
                        capture->start_bm_capture();
                }
        }
+
+#ifdef HAVE_SRT
+       // Same, for SRT inputs.
+       for (SRTSOCKET sock : hotplugged_srt_cards_copy) {
+               char name[256];
+               int namelen = sizeof(name);
+               srt_getsockopt(sock, /*ignored=*/0, SRTO_STREAMID, name, &namelen);
+               string stream_id(name, namelen);
+
+               // Look for a fake capture card where we can stick this in.
+               // Prioritize ones that previously held SRT streams with the
+               // same stream ID, if any exist -- and it multiple exist,
+               // take the one that disconnected the last.
+               int first_free_card_index = -1, last_matching_free_card_index = -1;
+               for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
+                       CaptureCard *card = &cards[card_index];
+                       if (!card->is_fake_capture) {
+                               continue;
+                       }
+                       if (first_free_card_index == -1) {
+                               first_free_card_index = card_index;
+                       }
+                       if (card->last_srt_stream_id == stream_id &&
+                           (last_matching_free_card_index == -1 ||
+                            card->fake_capture_counter >
+                               cards[last_matching_free_card_index].fake_capture_counter)) {
+                               last_matching_free_card_index = card_index;
+                       }
+               }
+
+               const int free_card_index = (last_matching_free_card_index != -1)
+                       ? last_matching_free_card_index : first_free_card_index;
+               if (free_card_index == -1 || num_video_cards >= global_flags.max_num_cards) {
+                       if (stream_id.empty()) {
+                               stream_id = "no name";
+                       }
+                       fprintf(stderr, "New SRT stream connected (%s), but no free slots -- ignoring.\n", stream_id.c_str());
+                       srt_close(sock);
+               } else {
+                       // FFmpegCapture takes ownership.
+                       if (stream_id.empty()) {
+                               fprintf(stderr, "New unnamed SRT stream connected, choosing slot %d.\n", free_card_index);
+                       } else {
+                               fprintf(stderr, "New SRT stream connected (%s), choosing slot %d.\n", stream_id.c_str(), free_card_index);
+                       }
+                       CaptureCard *card = &cards[free_card_index];
+                       FFmpegCapture *capture = new FFmpegCapture(sock, stream_id);
+                       capture->set_card_index(free_card_index);
+                       configure_card(free_card_index, capture, CardType::FFMPEG_INPUT, /*output=*/nullptr, /*is_srt_card=*/true);
+                       update_srt_stats(sock, card);  // Initial zero stats.
+                       card->last_srt_stream_id = stream_id;
+                       card->jitter_history.clear();
+                       capture->set_card_disconnected_callback(bind(&Mixer::bm_hotplug_remove, this, free_card_index));
+                       capture->start_bm_capture();
+               }
+       }
+#endif
+
+       // Finally, newly forced-to-active fake capture cards.
+       for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
+               CaptureCard *card = &cards[card_index];
+               if (card->capture == nullptr && card->force_active) {
+                       FakeCapture *capture = new FakeCapture(global_flags.width, global_flags.height, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
+                       configure_card(card_index, capture, CardType::FAKE_CAPTURE, /*output=*/nullptr, /*is_srt_card=*/false);
+                       card->jitter_history.clear();
+                       card->capture->start_bm_capture();
+               }
+       }
 }
 
 
 void Mixer::schedule_audio_resampling_tasks(unsigned dropped_frames, int num_samples_per_frame, int length_per_frame, bool is_preroll, steady_clock::time_point frame_timestamp)
 {
        // Resample the audio as needed, including from previously dropped frames.
-       assert(num_cards > 0);
        for (unsigned frame_num = 0; frame_num < dropped_frames + 1; ++frame_num) {
                const bool dropped_frame = (frame_num != dropped_frames);
                {
@@ -1379,7 +1781,7 @@ void Mixer::render_one_frame(int64_t duration)
        // Update Y'CbCr settings for all cards.
        {
                lock_guard<mutex> lock(card_mutex);
-               for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
+               for (unsigned card_index = 0; card_index < MAX_VIDEO_CARDS; ++card_index) {
                        YCbCrInterpretation *interpretation = &ycbcr_interpretation[card_index];
                        input_state.ycbcr_coefficients_auto[card_index] = interpretation->ycbcr_coefficients_auto;
                        input_state.ycbcr_coefficients[card_index] = interpretation->ycbcr_coefficients;
@@ -1570,6 +1972,23 @@ void Mixer::quit()
        audio_task_queue_changed.notify_one();
        mixer_thread.join();
        audio_thread.join();
+#ifdef HAVE_SRT
+       if (global_flags.srt_port >= 0) {
+               // There's seemingly no other reasonable way to wake up the thread
+               // (libsrt's epoll equivalent is busy-waiting).
+               int sock = srt_create_socket();
+               if (sock != -1) {
+                       sockaddr_in6 addr;
+                       memset(&addr, 0, sizeof(addr));
+                       addr.sin6_family = AF_INET6;
+                       addr.sin6_addr = IN6ADDR_LOOPBACK_INIT;
+                       addr.sin6_port = htons(global_flags.srt_port);
+                       srt_connect(sock, (sockaddr *)&addr, sizeof(addr));
+                       srt_close(sock);
+               }
+               srt_thread.join();
+       }
+#endif
 }
 
 void Mixer::transition_clicked(int transition_num)
@@ -1596,7 +2015,11 @@ void Mixer::set_input_ycbcr_interpretation(unsigned card_index, const YCbCrInter
 
 void Mixer::start_mode_scanning(unsigned card_index)
 {
-       assert(card_index < num_cards);
+       assert(card_index < MAX_VIDEO_CARDS);
+       if (cards[card_index].capture != nullptr) {
+               // Inactive card. Should never happen.
+               return;
+       }
        if (is_mode_scanning[card_index]) {
                return;
        }
@@ -1620,12 +2043,14 @@ map<uint32_t, VideoMode> Mixer::get_available_output_video_modes() const
 
 string Mixer::get_ffmpeg_filename(unsigned card_index) const
 {
-       assert(card_index >= num_cards && card_index < num_cards + num_video_inputs);
+       assert(card_index < MAX_VIDEO_CARDS);
+       assert(cards[card_index].type == CardType::FFMPEG_INPUT);
        return ((FFmpegCapture *)(cards[card_index].capture.get()))->get_filename();
 }
 
 void Mixer::set_ffmpeg_filename(unsigned card_index, const string &filename) {
-       assert(card_index >= num_cards && card_index < num_cards + num_video_inputs);
+       assert(card_index < MAX_VIDEO_CARDS);
+       assert(cards[card_index].type == CardType::FFMPEG_INPUT);
        ((FFmpegCapture *)(cards[card_index].capture.get()))->change_filename(filename);
 }
 
@@ -1757,4 +2182,142 @@ void Mixer::OutputChannel::set_color_updated_callback(Mixer::color_updated_callb
        color_updated_callback = callback;
 }
 
+#ifdef HAVE_SRT
+void Mixer::start_srt()
+{
+       SRTSOCKET sock = srt_create_socket();
+       sockaddr_in6 addr;
+       memset(&addr, 0, sizeof(addr));
+       addr.sin6_family = AF_INET6;
+       addr.sin6_port = htons(global_flags.srt_port);
+
+       int err = srt_bind(sock, (sockaddr *)&addr, sizeof(addr));
+       if (err != 0) {
+               fprintf(stderr, "srt_bind: %s\n", srt_getlasterror_str());
+               abort();
+       }
+       err = srt_listen(sock, MAX_VIDEO_CARDS);
+       if (err != 0) {
+               fprintf(stderr, "srt_listen: %s\n", srt_getlasterror_str());
+               abort();
+       }
+
+       srt_thread = thread([this, sock] {
+               sockaddr_in6 addr;
+               for ( ;; ) {
+                       int sa_len = sizeof(addr);
+                       int clientsock = srt_accept(sock, (sockaddr *)&addr, &sa_len);
+                       if (should_quit) {
+                               if (clientsock != -1) {
+                                       srt_close(clientsock);
+                               }
+                               break;
+                       }
+                       if (!global_flags.enable_srt) {  // Runtime UI toggle.
+                               // Perhaps not as good as never listening in the first place,
+                               // but much simpler to turn on and off.
+                               srt_close(clientsock);
+                               continue;
+                       }
+                       lock_guard<mutex> lock(hotplug_mutex);
+                       hotplugged_srt_cards.push_back(clientsock);
+               }
+               srt_close(sock);
+       });
+}
+#endif
+
+#ifdef HAVE_SRT
+void Mixer::update_srt_stats(int srt_sock, Mixer::CaptureCard *card)
+{
+       SRT_TRACEBSTATS stats;
+       srt_bistats(srt_sock, &stats, /*clear=*/0, /*instantaneous=*/1);
+
+       card->metric_srt_uptime_seconds = stats.msTimeStamp * 1e-3;
+       card->metric_srt_send_duration_seconds = stats.usSndDurationTotal * 1e-6;
+       card->metric_srt_sent_bytes = stats.byteSentTotal;
+       card->metric_srt_received_bytes = stats.byteRecvTotal;
+       card->metric_srt_sent_packets_normal = stats.pktSentTotal;
+       card->metric_srt_received_packets_normal = stats.pktRecvTotal;
+       card->metric_srt_sent_packets_lost = stats.pktSndLossTotal;
+       card->metric_srt_received_packets_lost = stats.pktRcvLossTotal;
+       card->metric_srt_sent_packets_retransmitted = stats.pktRetransTotal;
+       card->metric_srt_sent_bytes_retransmitted = stats.byteRetransTotal;
+       card->metric_srt_sent_packets_ack = stats.pktSentACKTotal;
+       card->metric_srt_received_packets_ack = stats.pktRecvACKTotal;
+       card->metric_srt_sent_packets_nak = stats.pktSentNAKTotal;
+       card->metric_srt_received_packets_nak = stats.pktRecvNAKTotal;
+       card->metric_srt_sent_packets_dropped = stats.pktSndDropTotal;
+       card->metric_srt_received_packets_dropped = stats.pktRcvDropTotal;
+       card->metric_srt_sent_bytes_dropped = stats.byteSndDropTotal;
+       card->metric_srt_received_bytes_dropped = stats.byteRcvDropTotal;
+       card->metric_srt_received_packets_undecryptable = stats.pktRcvUndecryptTotal;
+       card->metric_srt_received_bytes_undecryptable = stats.byteRcvUndecryptTotal;
+       card->metric_srt_filter_sent_packets = stats.pktSndFilterExtraTotal;
+       card->metric_srt_filter_received_extra_packets = stats.pktRcvFilterExtraTotal;
+       card->metric_srt_filter_received_rebuilt_packets = stats.pktRcvFilterSupplyTotal;
+       card->metric_srt_filter_received_lost_packets = stats.pktRcvFilterLossTotal;
+
+       // Gauges.
+       card->metric_srt_packet_sending_period_seconds = stats.usPktSndPeriod * 1e-6;
+       card->metric_srt_flow_window_packets = stats.pktFlowWindow;
+       card->metric_srt_congestion_window_packets = stats.pktCongestionWindow;
+       card->metric_srt_flight_size_packets = stats.pktFlightSize;
+       card->metric_srt_rtt_seconds = stats.msRTT * 1e-3;
+       card->metric_srt_estimated_bandwidth_bits_per_second = stats.mbpsBandwidth * 1e6;
+       card->metric_srt_bandwidth_ceiling_bits_per_second = stats.mbpsMaxBW * 1e6;
+       card->metric_srt_send_buffer_available_bytes = stats.byteAvailSndBuf;
+       card->metric_srt_receive_buffer_available_bytes = stats.byteAvailRcvBuf;
+       card->metric_srt_mss_bytes = stats.byteMSS;
+       card->metric_srt_sender_unacked_packets = stats.pktSndBuf;
+       card->metric_srt_sender_unacked_bytes = stats.byteSndBuf;
+       card->metric_srt_sender_unacked_timespan_seconds = stats.msSndBuf * 1e-3;
+       card->metric_srt_sender_delivery_delay_seconds = stats.msSndTsbPdDelay * 1e-3;
+       card->metric_srt_receiver_unacked_packets = stats.pktRcvBuf;
+       card->metric_srt_receiver_unacked_bytes = stats.byteRcvBuf;
+       card->metric_srt_receiver_unacked_timespan_seconds = stats.msRcvBuf * 1e-3;
+       card->metric_srt_receiver_delivery_delay_seconds = stats.msRcvTsbPdDelay * 1e-3;
+}
+#endif
+
+string Mixer::description_for_card(unsigned card_index)
+{
+       CaptureCard *card = &cards[card_index];
+       if (card->capture == nullptr) {
+               // Should never be called for inactive cards, but OK.
+               char buf[256];
+               snprintf(buf, sizeof(buf), "Inactive capture card %u", card_index);
+               return buf;
+       }
+       if (card->type != CardType::FFMPEG_INPUT) {
+               char buf[256];
+               snprintf(buf, sizeof(buf), "Capture card %u (%s)", card_index, card->capture->get_description().c_str());
+               return buf;
+       }
+
+       // Number (non-SRT) FFmpeg inputs from zero, separately from the capture cards,
+       // since it's not too obvious for the user that they are “cards”.
+       unsigned ffmpeg_index = 0;
+       for (unsigned i = 0; i < card_index; ++i) {
+               CaptureCard *other_card = &cards[i];
+               if (other_card->type == CardType::FFMPEG_INPUT && !is_srt_card(other_card)) {
+                       ++ffmpeg_index;
+               }
+       }
+       char buf[256];
+       snprintf(buf, sizeof(buf), "Video input %u (%s)", ffmpeg_index, card->capture->get_description().c_str());
+       return buf;
+}
+
+bool Mixer::is_srt_card(const Mixer::CaptureCard *card)
+{
+#ifdef HAVE_SRT
+       if (card->type == CardType::FFMPEG_INPUT) {
+               int srt_sock = static_cast<FFmpegCapture *>(card->capture.get())->get_srt_sock();
+               return srt_sock != -1;
+       }
+#endif
+       return false;
+}
+
 mutex RefCountedGLsync::fence_lock;