]> git.sesse.net Git - nageru/blobdiff - mixer.cpp
Various Makefile tweaks (mostly related to cleaning moc files).
[nageru] / mixer.cpp
index 1f1035bf84065ef9c7ccca19afb8a5a51a1075e0..780bd52573c3380404cd77a36aa1892bfa8642cf 100644 (file)
--- a/mixer.cpp
+++ b/mixer.cpp
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <sys/time.h>
-#include <time.h>
+#include <sys/resource.h>
 #include <algorithm>
-#include <cmath>
+#include <chrono>
 #include <condition_variable>
 #include <cstddef>
+#include <cstdint>
 #include <memory>
 #include <mutex>
+#include <ratio>
 #include <string>
 #include <thread>
 #include <utility>
 #include <vector>
-#include <arpa/inet.h>
 
+#include "DeckLinkAPI.h"
+#include "LinuxCOM.h"
+#include "alsa_output.h"
 #include "bmusb/bmusb.h"
+#include "bmusb/fake_capture.h"
 #include "context.h"
 #include "decklink_capture.h"
 #include "defs.h"
+#include "disk_space_estimator.h"
 #include "flags.h"
-#include "h264encode.h"
+#include "input_mapping.h"
 #include "pbo_frame_allocator.h"
 #include "ref_counted_gl_sync.h"
+#include "resampling_queue.h"
 #include "timebase.h"
+#include "video_encoder.h"
 
+class IDeckLink;
 class QOpenGLContext;
 
 using namespace movit;
 using namespace std;
+using namespace std::chrono;
 using namespace std::placeholders;
+using namespace bmusb;
 
 Mixer *global_mixer = nullptr;
+bool uses_mlock = false;
 
 namespace {
 
-void convert_fixed24_to_fp32(float *dst, size_t out_channels, const uint8_t *src, size_t in_channels, size_t num_samples)
-{
-       assert(in_channels >= out_channels);
-       for (size_t i = 0; i < num_samples; ++i) {
-               for (size_t j = 0; j < out_channels; ++j) {
-                       uint32_t s1 = *src++;
-                       uint32_t s2 = *src++;
-                       uint32_t s3 = *src++;
-                       uint32_t s = s1 | (s1 << 8) | (s2 << 16) | (s3 << 24);
-                       dst[i * out_channels + j] = int(s) * (1.0f / 4294967296.0f);
-               }
-               src += 3 * (in_channels - out_channels);
-       }
-}
-
-void convert_fixed32_to_fp32(float *dst, size_t out_channels, const uint8_t *src, size_t in_channels, size_t num_samples)
-{
-       assert(in_channels >= out_channels);
-       for (size_t i = 0; i < num_samples; ++i) {
-               for (size_t j = 0; j < out_channels; ++j) {
-                       // Note: Assumes little-endian.
-                       int32_t s = *(int32_t *)src;
-                       dst[i * out_channels + j] = s * (1.0f / 4294967296.0f);
-                       src += 4;
-               }
-               src += 4 * (in_channels - out_channels);
-       }
-}
-
 void insert_new_frame(RefCountedFrame frame, unsigned field_num, bool interlaced, unsigned card_index, InputState *input_state)
 {
        if (interlaced) {
@@ -92,23 +74,6 @@ void insert_new_frame(RefCountedFrame frame, unsigned field_num, bool interlaced
        }
 }
 
-string generate_local_dump_filename(int frame)
-{
-       time_t now = time(NULL);
-       tm now_tm;
-       localtime_r(&now, &now_tm);
-
-       char timestamp[256];
-       strftime(timestamp, sizeof(timestamp), "%F-%T%z", &now_tm);
-
-       // Use the frame number to disambiguate between two cuts starting
-       // on the same second.
-       char filename[256];
-       snprintf(filename, sizeof(filename), "%s%s-f%02d%s",
-               LOCAL_DUMP_PREFIX, timestamp, frame % 100, LOCAL_DUMP_SUFFIX);
-       return filename;
-}
-
 }  // namespace
 
 void QueueLengthPolicy::update_policy(int queue_length)
@@ -127,9 +92,9 @@ void QueueLengthPolicy::update_policy(int queue_length)
                if (queue_length >= int(safe_queue_length)) {
                        been_at_safe_point_since_last_starvation = true;
                }
-               if (++frames_with_at_least_one >= 50 && safe_queue_length > 0) {
+               if (++frames_with_at_least_one >= 1000 && safe_queue_length > 0) {
                        --safe_queue_length;
-                       fprintf(stderr, "Card %u: Spare frames for more than 50 frames, reducing safe limit to %u frames\n",
+                       fprintf(stderr, "Card %u: Spare frames for more than 1000 frames, reducing safe limit to %u frames\n",
                                card_index, safe_queue_length);
                        frames_with_at_least_one = 0;
                }
@@ -139,18 +104,12 @@ void QueueLengthPolicy::update_policy(int queue_length)
 }
 
 Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
-       : httpd(WIDTH, HEIGHT),
+       : httpd(),
          num_cards(num_cards),
          mixer_surface(create_surface(format)),
          h264_encoder_surface(create_surface(format)),
-         correlation(OUTPUT_FREQUENCY),
-         level_compressor(OUTPUT_FREQUENCY),
-         limiter(OUTPUT_FREQUENCY),
-         compressor(OUTPUT_FREQUENCY)
+         audio_mixer(num_cards)
 {
-       httpd.open_output_file(generate_local_dump_filename(/*frame=*/0).c_str());
-       httpd.start(9095);
-
        CHECK(init_movit(MOVIT_SHADER_DIR, MOVIT_DEBUG_OFF));
        check_error();
 
@@ -159,9 +118,10 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        movit_texel_subpixel_precision /= 2.0;
 
        resource_pool.reset(new ResourcePool);
-       theme.reset(new Theme(global_flags.theme_filename.c_str(), resource_pool.get(), num_cards));
+       theme.reset(new Theme(global_flags.theme_filename, global_flags.theme_dirs, resource_pool.get(), num_cards));
        for (unsigned i = 0; i < NUM_OUTPUTS; ++i) {
                output_channel[i].parent = this;
+               output_channel[i].channel = i;
        }
 
        ImageFormat inout_format;
@@ -177,37 +137,55 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        display_chain->set_dither_bits(0);  // Don't bother.
        display_chain->finalize();
 
-       h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
+       video_encoder.reset(new VideoEncoder(resource_pool.get(), h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd, global_disk_space_estimator));
 
-       // First try initializing the PCI devices, then USB, until we have the desired number of cards.
-       unsigned num_pci_devices = 0, num_usb_devices = 0;
+       // Start listening for clients only once VideoEncoder has written its header, if any.
+       httpd.start(9095);
+
+       // First try initializing the then PCI devices, then USB, then
+       // fill up with fake cards until we have the desired number of cards.
+       unsigned num_pci_devices = 0;
        unsigned card_index = 0;
 
-       IDeckLinkIterator *decklink_iterator = CreateDeckLinkIteratorInstance();
-       if (decklink_iterator != nullptr) {
-               for ( ; card_index < num_cards; ++card_index) {
-                       IDeckLink *decklink;
-                       if (decklink_iterator->Next(&decklink) != S_OK) {
-                               break;
+       {
+               IDeckLinkIterator *decklink_iterator = CreateDeckLinkIteratorInstance();
+               if (decklink_iterator != nullptr) {
+                       for ( ; card_index < num_cards; ++card_index) {
+                               IDeckLink *decklink;
+                               if (decklink_iterator->Next(&decklink) != S_OK) {
+                                       break;
+                               }
+
+                               configure_card(card_index, new DeckLinkCapture(decklink, card_index), /*is_fake_capture=*/false);
+                               ++num_pci_devices;
                        }
-
-                       configure_card(card_index, format, new DeckLinkCapture(decklink, card_index));
-                       ++num_pci_devices;
+                       decklink_iterator->Release();
+                       fprintf(stderr, "Found %u DeckLink PCI card(s).\n", num_pci_devices);
+               } else {
+                       fprintf(stderr, "DeckLink drivers not found. Probing for USB cards only.\n");
                }
-               decklink_iterator->Release();
-               fprintf(stderr, "Found %d DeckLink PCI card(s).\n", num_pci_devices);
-       } else {
-               fprintf(stderr, "DeckLink drivers not found. Probing for USB cards only.\n");
        }
-       for ( ; card_index < num_cards; ++card_index) {
-               configure_card(card_index, format, new BMUSBCapture(card_index - num_pci_devices));
-               ++num_usb_devices;
+       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) {
+               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, /*is_fake_capture=*/false);
+       }
+       fprintf(stderr, "Found %u USB card(s).\n", num_usb_devices);
+
+       unsigned num_fake_cards = 0;
+       for ( ; card_index < num_cards; ++card_index, ++num_fake_cards) {
+               FakeCapture *capture = new FakeCapture(WIDTH, HEIGHT, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
+               configure_card(card_index, capture, /*is_fake_capture=*/true);
        }
 
-       if (num_usb_devices > 0) {
-               BMUSBCapture::start_bm_thread();
+       if (num_fake_cards > 0) {
+               fprintf(stderr, "Initialized %u fake cards.\n", num_fake_cards);
        }
 
+       BMUSBCapture::set_card_connected_callback(bind(&Mixer::bm_hotplug_add, this, _1));
+       BMUSBCapture::start_bm_thread();
+
        for (card_index = 0; card_index < num_cards; ++card_index) {
                cards[card_index].queue_length_policy.reset(card_index);
                cards[card_index].capture->start_bm_capture();
@@ -256,24 +234,9 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        cbcr_position_attribute_index = glGetAttribLocation(cbcr_program_num, "position");
        cbcr_texcoord_attribute_index = glGetAttribLocation(cbcr_program_num, "texcoord");
 
-       r128.init(2, OUTPUT_FREQUENCY);
-       r128.integr_start();
-
-       locut.init(FILTER_HPF, 2);
-
-       // If --flat-audio is given, turn off everything that messes with the sound,
-       // except the final makeup gain.
-       if (global_flags.flat_audio) {
-               set_locut_enabled(false);
-               set_limiter_enabled(false);
-               set_compressor_enabled(false);
+       if (global_flags.enable_alsa_output) {
+               alsa.reset(new ALSAOutput(OUTPUT_FREQUENCY, /*num_channels=*/2));
        }
-
-       // hlen=16 is pretty low quality, but we use quite a bit of CPU otherwise,
-       // and there's a limit to how important the peak meter is.
-       peak_resampler.setup(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY * 4, /*num_channels=*/2, /*hlen=*/16, /*frel=*/1.0);
-
-       alsa.reset(new ALSAOutput(OUTPUT_FREQUENCY, /*num_channels=*/2));
 }
 
 Mixer::~Mixer()
@@ -291,33 +254,37 @@ Mixer::~Mixer()
                cards[card_index].capture->stop_dequeue_thread();
        }
 
-       h264_encoder.reset(nullptr);
+       video_encoder.reset(nullptr);
 }
 
-void Mixer::configure_card(unsigned card_index, const QSurfaceFormat &format, CaptureInterface *capture)
+void Mixer::configure_card(unsigned card_index, CaptureInterface *capture, bool is_fake_capture)
 {
        printf("Configuring card %d...\n", card_index);
 
        CaptureCard *card = &cards[card_index];
+       if (card->capture != nullptr) {
+               card->capture->stop_dequeue_thread();
+               delete card->capture;
+       }
        card->capture = capture;
+       card->is_fake_capture = is_fake_capture;
        card->capture->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
-       card->frame_allocator.reset(new PBOFrameAllocator(8 << 20, WIDTH, HEIGHT));  // 8 MB.
+       if (card->frame_allocator == nullptr) {
+               card->frame_allocator.reset(new PBOFrameAllocator(8 << 20, WIDTH, HEIGHT));  // 8 MB.
+       }
        card->capture->set_video_frame_allocator(card->frame_allocator.get());
-       card->surface = create_surface(format);
-       card->capture->set_dequeue_thread_callbacks(
-               [card]{
-                       eglBindAPI(EGL_OPENGL_API);
-                       card->context = create_context(card->surface);
-                       if (!make_current(card->context, card->surface)) {
-                               printf("failed to create bmusb context\n");
-                               exit(1);
-                       }
-               },
-               [this]{
-                       resource_pool->clean_context();
-               });
-       card->resampling_queue.reset(new ResamplingQueue(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY, 2));
+       if (card->surface == nullptr) {
+               card->surface = create_surface_with_same_format(mixer_surface);
+       }
+       while (!card->new_frames.empty()) card->new_frames.pop();
+       card->fractional_samples = 0;
+       card->last_timecode = -1;
        card->capture->configure_card();
+
+       DeviceSpec device{InputSourceType::CAPTURE_CARD, card_index};
+       audio_mixer.reset_resampler(device);
+       audio_mixer.set_display_name(device, card->capture->get_description());
+       audio_mixer.trigger_state_changed_callback();
 }
 
 
@@ -333,36 +300,13 @@ int unwrap_timecode(uint16_t current_wrapped, int last)
        }
 }
 
-float find_peak(const float *samples, size_t num_samples)
-{
-       float m = fabs(samples[0]);
-       for (size_t i = 1; i < num_samples; ++i) {
-               m = max(m, fabs(samples[i]));
-       }
-       return m;
-}
-
-void deinterleave_samples(const vector<float> &in, vector<float> *out_l, vector<float> *out_r)
-{
-       size_t num_samples = in.size() / 2;
-       out_l->resize(num_samples);
-       out_r->resize(num_samples);
-
-       const float *inptr = in.data();
-       float *lptr = &(*out_l)[0];
-       float *rptr = &(*out_r)[0];
-       for (size_t i = 0; i < num_samples; ++i) {
-               *lptr++ = *inptr++;
-               *rptr++ = *inptr++;
-       }
-}
-
 }  // 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{InputSourceType::CAPTURE_CARD, card_index};
        CaptureCard *card = &cards[card_index];
 
        if (is_mode_scanning[card_index]) {
@@ -371,10 +315,8 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                        is_mode_scanning[card_index] = false;
                } else {
                        static constexpr double switch_time_s = 0.5;  // Should be enough time for the signal to stabilize.
-                       timespec now;
-                       clock_gettime(CLOCK_MONOTONIC, &now);
-                       double sec_since_last_switch = (now.tv_sec - last_mode_scan_change[card_index].tv_sec) +
-                               1e-9 * (now.tv_nsec - last_mode_scan_change[card_index].tv_nsec);
+                       steady_clock::time_point now = steady_clock::now();
+                       double sec_since_last_switch = duration<double>(steady_clock::now() - last_mode_scan_change[card_index]).count();
                        if (sec_since_last_switch > switch_time_s) {
                                // It isn't this mode; try the next one.
                                mode_scanlist_index[card_index]++;
@@ -385,7 +327,8 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                }
        }
 
-       int64_t frame_length = int64_t(TIMEBASE * video_format.frame_rate_den) / video_format.frame_rate_nom;
+       int64_t frame_length = int64_t(TIMEBASE) * video_format.frame_rate_den / video_format.frame_rate_nom;
+       assert(frame_length > 0);
 
        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) {
@@ -401,71 +344,40 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                return;
        }
 
-       int64_t local_pts = card->next_local_pts;
        int dropped_frames = 0;
        if (card->last_timecode != -1) {
                dropped_frames = unwrap_timecode(timecode, card->last_timecode) - card->last_timecode - 1;
        }
 
-       // Convert the audio to stereo fp32 and add it.
-       vector<float> audio;
-       audio.resize(num_samples * 2);
-       switch (audio_format.bits_per_sample) {
-       case 0:
-               assert(num_samples == 0);
-               break;
-       case 24:
-               convert_fixed24_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, audio_format.num_channels, num_samples);
-               break;
-       case 32:
-               convert_fixed32_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, audio_format.num_channels, num_samples);
-               break;
-       default:
-               fprintf(stderr, "Cannot handle audio with %u bits per sample\n", audio_format.bits_per_sample);
-               assert(false);
-       }
-
-       // Add the audio.
-       {
-               unique_lock<mutex> lock(card->audio_mutex);
-
-               // Number of samples per frame if we need to insert silence.
-               // (Could be nonintegral, but resampling will save us then.)
-               int silence_samples = OUTPUT_FREQUENCY * video_format.frame_rate_den / video_format.frame_rate_nom;
-
-               if (dropped_frames > MAX_FPS * 2) {
-                       fprintf(stderr, "Card %d lost more than two seconds (or time code jumping around; from 0x%04x to 0x%04x), resetting resampler\n",
-                               card_index, card->last_timecode, timecode);
-                       card->resampling_queue.reset(new ResamplingQueue(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY, 2));
-                       dropped_frames = 0;
-               } else if (dropped_frames > 0) {
-                       // Insert silence as needed.
-                       fprintf(stderr, "Card %d dropped %d frame(s) (before timecode 0x%04x), inserting silence.\n",
-                               card_index, dropped_frames, timecode);
-                       vector<float> silence(silence_samples * 2, 0.0f);
-                       for (int i = 0; i < dropped_frames; ++i) {
-                               card->resampling_queue->add_input_samples(local_pts / double(TIMEBASE), silence.data(), silence_samples);
-                               // Note that if the format changed in the meantime, we have
-                               // no way of detecting that; we just have to assume the frame length
-                               // is always the same.
-                               local_pts += frame_length;
-                       }
-               }
-               if (num_samples == 0) {
-                       audio.resize(silence_samples * 2);
-                       num_samples = silence_samples;
-               }
-               card->resampling_queue->add_input_samples(local_pts / double(TIMEBASE), audio.data(), num_samples);
-               card->next_local_pts = local_pts + frame_length;
+       // Number of samples per frame if we need to insert silence.
+       // (Could be nonintegral, but resampling will save us then.)
+       const int silence_samples = OUTPUT_FREQUENCY * video_format.frame_rate_den / video_format.frame_rate_nom;
+
+       if (dropped_frames > MAX_FPS * 2) {
+               fprintf(stderr, "Card %d lost more than two seconds (or time code jumping around; from 0x%04x to 0x%04x), resetting resampler\n",
+                       card_index, card->last_timecode, timecode);
+               audio_mixer.reset_resampler(device);
+               dropped_frames = 0;
+       } else if (dropped_frames > 0) {
+               // Insert silence as needed.
+               fprintf(stderr, "Card %d dropped %d frame(s) (before timecode 0x%04x), inserting silence.\n",
+                       card_index, dropped_frames, timecode);
+
+               bool success;
+               do {
+                       success = audio_mixer.add_silence(device, silence_samples, dropped_frames, frame_length);
+               } while (!success);
        }
 
-       card->last_timecode = timecode;
+       audio_mixer.add_audio(device, audio_frame.data + audio_offset, num_samples, audio_format, frame_length);
 
        // Done with the audio, so release it.
        if (audio_frame.owner) {
                audio_frame.owner->release_frame(audio_frame);
        }
 
+       card->last_timecode = timecode;
+
        size_t expected_length = video_format.width * (video_format.height + video_format.extra_lines_top + video_format.extra_lines_bottom) * 2;
        if (video_frame.len - video_offset == 0 ||
            video_frame.len - video_offset != expected_length) {
@@ -495,7 +407,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        PBOFrameAllocator::Userdata *userdata = (PBOFrameAllocator::Userdata *)video_frame.userdata;
 
        unsigned num_fields = video_format.interlaced ? 2 : 1;
-       timespec frame_upload_start;
+       steady_clock::time_point frame_upload_start;
        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.
@@ -504,10 +416,11 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                assert(frame_length % 2 == 0);
                frame_length /= 2;
                num_fields = 2;
-               clock_gettime(CLOCK_MONOTONIC, &frame_upload_start);
+               frame_upload_start = steady_clock::now();
        }
        userdata->last_interlaced = video_format.interlaced;
        userdata->last_has_signal = video_format.has_signal;
+       userdata->last_is_connected = video_format.is_connected;
        userdata->last_frame_rate_nom = video_format.frame_rate_nom;
        userdata->last_frame_rate_den = video_format.frame_rate_den;
        RefCountedFrame frame(video_frame);
@@ -518,49 +431,64 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        size_t y_offset = video_frame.size / 2 + video_offset / 2;
 
        for (unsigned field = 0; field < num_fields; ++field) {
-               unsigned field_start_line = (field == 1) ? video_format.second_field_start : video_format.extra_lines_top + field * (video_format.height + 22);
-
-               if (userdata->tex_y[field] == 0 ||
-                   userdata->tex_cbcr[field] == 0 ||
-                   video_format.width != userdata->last_width[field] ||
-                   video_format.height != userdata->last_height[field]) {
-                       // 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.
+               // 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 = [field, video_format, y_offset, cbcr_offset, cbcr_width, userdata]() {
+                       unsigned field_start_line = (field == 1) ? video_format.second_field_start : video_format.extra_lines_top + field * (video_format.height + 22);
+
+                       if (userdata->tex_y[field] == 0 ||
+                           userdata->tex_cbcr[field] == 0 ||
+                           video_format.width != userdata->last_width[field] ||
+                           video_format.height != userdata->last_height[field]) {
+                               // 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.
+                               glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
+                               check_error();
+                               glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, cbcr_width, video_format.height, 0, GL_RG, GL_UNSIGNED_BYTE, nullptr);
+                               check_error();
+                               glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
+                               check_error();
+                               glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, video_format.width, video_format.height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
+                               check_error();
+                               userdata->last_width[field] = video_format.width;
+                               userdata->last_height[field] = video_format.height;
+                       }
+
+                       GLuint pbo = userdata->pbo;
+                       check_error();
+                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo);
+                       check_error();
+
+                       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);
+
+                       if (global_flags.flush_pbos) {
+                               glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, field_y_start, video_format.width * video_format.height);
+                               check_error();
+                               glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, field_cbcr_start, cbcr_width * video_format.height * sizeof(uint16_t));
+                               check_error();
+                       }
+
                        glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
                        check_error();
-                       glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, cbcr_width, video_format.height, 0, GL_RG, GL_UNSIGNED_BYTE, nullptr);
+                       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, cbcr_width, video_format.height, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(field_cbcr_start));
                        check_error();
                        glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
                        check_error();
-                       glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, video_format.width, video_format.height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
+                       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, video_format.width, video_format.height, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(field_y_start));
                        check_error();
-                       userdata->last_width[field] = video_format.width;
-                       userdata->last_height[field] = video_format.height;
-               }
-
-               GLuint pbo = userdata->pbo;
-               check_error();
-               glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo);
-               check_error();
-               glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, video_frame.size);
-               check_error();
-
-               glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
-               check_error();
-               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, cbcr_width, video_format.height, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(cbcr_offset + cbcr_width * field_start_line * sizeof(uint16_t)));
-               check_error();
-               glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
-               check_error();
-               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, video_format.width, video_format.height, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(y_offset + video_format.width * field_start_line));
-               check_error();
-               glBindTexture(GL_TEXTURE_2D, 0);
-               check_error();
-               glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
-               check_error();
-               RefCountedGLsync fence(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
-               check_error();
-               assert(fence.get() != nullptr);
+                       glBindTexture(GL_TEXTURE_2D, 0);
+                       check_error();
+                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+                       check_error();
+               };
 
                if (field == 1) {
                        // Don't upload the second field as fast as we can; wait until
@@ -569,16 +497,9 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                        // against the video display, although the latter is not as critical.)
                        // This requires our system clock to be reasonably close to the
                        // video clock, but that's not an unreasonable assumption.
-                       timespec second_field_start;
-                       second_field_start.tv_nsec = frame_upload_start.tv_nsec +
-                               frame_length * 1000000000 / TIMEBASE;
-                       second_field_start.tv_sec = frame_upload_start.tv_sec +
-                               second_field_start.tv_nsec / 1000000000;
-                       second_field_start.tv_nsec %= 1000000000;
-
-                       while (clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME,
-                                              &second_field_start, nullptr) == -1 &&
-                              errno == EINTR) ;
+                       steady_clock::time_point second_field_start = frame_upload_start +
+                               nanoseconds(frame_length * 1000000000 / TIMEBASE);
+                       this_thread::sleep_until(second_field_start);
                }
 
                {
@@ -588,7 +509,7 @@ 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.ready_fence = fence;
+                       new_frame.upload_func = upload_func;
                        new_frame.dropped_frames = dropped_frames;
                        card->new_frames.push(move(new_frame));
                        card->new_frames_changed.notify_all();
@@ -596,6 +517,17 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        }
 }
 
+void Mixer::bm_hotplug_add(libusb_device *dev)
+{
+       lock_guard<mutex> lock(hotplug_mutex);
+       hotplugged_cards.push_back(dev);
+}
+
+void Mixer::bm_hotplug_remove(unsigned card_index)
+{
+       cards[card_index].new_frames_changed.notify_all();
+}
+
 void Mixer::thread_func()
 {
        eglBindAPI(EGL_OPENGL_API);
@@ -605,25 +537,25 @@ void Mixer::thread_func()
                exit(1);
        }
 
-       struct timespec start, now;
-       clock_gettime(CLOCK_MONOTONIC, &start);
+       steady_clock::time_point start, now;
+       start = steady_clock::now();
 
        int frame = 0;
        int stats_dropped_frames = 0;
 
        while (!should_quit) {
-               CaptureCard::NewFrame new_frames[MAX_CARDS];
-               bool has_new_frame[MAX_CARDS] = { false };
-               int num_samples[MAX_CARDS] = { 0 };
+               CaptureCard::NewFrame new_frames[MAX_VIDEO_CARDS];
+               bool has_new_frame[MAX_VIDEO_CARDS] = { false };
+               int num_samples[MAX_VIDEO_CARDS] = { 0 };
 
-               // TODO: Add a timeout.
                unsigned master_card_index = theme->map_signal(master_clock_channel);
                assert(master_card_index < num_cards);
 
                get_one_frame_from_each_card(master_card_index, new_frames, has_new_frame, num_samples);
                schedule_audio_resampling_tasks(new_frames[master_card_index].dropped_frames, num_samples[master_card_index], new_frames[master_card_index].length);
                stats_dropped_frames += new_frames[master_card_index].dropped_frames;
-               send_audio_level_callback();
+
+               handle_hotplugged_cards();
 
                for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
                        if (card_index == master_card_index || !has_new_frame[card_index]) {
@@ -655,37 +587,56 @@ void Mixer::thread_func()
                        insert_new_frame(new_frame->frame, new_frame->field, new_frame->interlaced, card_index, &input_state);
                        check_error();
 
-                       // The new texture might still be uploaded,
-                       // tell the GPU to wait until it's there.
-                       if (new_frame->ready_fence) {
-                               glWaitSync(new_frame->ready_fence.get(), /*flags=*/0, GL_TIMEOUT_IGNORED);
-                               check_error();
-                               new_frame->ready_fence.reset();
-                               check_error();
+                       // The new texture might need uploading before use.
+                       if (new_frame->upload_func) {
+                               new_frame->upload_func();
+                               new_frame->upload_func = nullptr;
                        }
                }
 
-               render_one_frame();
+               int64_t frame_duration = new_frames[master_card_index].length;
+               render_one_frame(frame_duration);
                ++frame;
-               pts_int += new_frames[master_card_index].length;
+               pts_int += frame_duration;
 
-               clock_gettime(CLOCK_MONOTONIC, &now);
-               double elapsed = now.tv_sec - start.tv_sec +
-                       1e-9 * (now.tv_nsec - start.tv_nsec);
+               now = steady_clock::now();
+               double elapsed = duration<double>(now - start).count();
                if (frame % 100 == 0) {
-                       printf("%d frames (%d dropped) in %.3f seconds = %.1f fps (%.1f ms/frame)\n",
+                       printf("%d frames (%d dropped) in %.3f seconds = %.1f fps (%.1f ms/frame)",
                                frame, stats_dropped_frames, elapsed, frame / elapsed,
                                1e3 * elapsed / frame);
                //      chain->print_phase_timing();
+
+                       // Check our memory usage, to see if we are close to our mlockall()
+                       // limit (if at all set).
+                       rusage used;
+                       if (getrusage(RUSAGE_SELF, &used) == -1) {
+                               perror("getrusage(RUSAGE_SELF)");
+                               assert(false);
+                       }
+
+                       if (uses_mlock) {
+                               rlimit limit;
+                               if (getrlimit(RLIMIT_MEMLOCK, &limit) == -1) {
+                                       perror("getrlimit(RLIMIT_MEMLOCK)");
+                                       assert(false);
+                               }
+
+                               printf(", using %ld / %ld MB lockable memory (%.1f%%)",
+                                       long(used.ru_maxrss / 1024),
+                                       long(limit.rlim_cur / 1048576),
+                                       float(100.0 * (used.ru_maxrss * 1024.0) / limit.rlim_cur));
+                       } else {
+                               printf(", using %ld MB memory (not locked)",
+                                       long(used.ru_maxrss / 1024));
+                       }
+
+                       printf("\n");
                }
 
+
                if (should_cut.exchange(false)) {  // Test and clear.
-                       string filename = generate_local_dump_filename(frame);
-                       printf("Starting new recording: %s\n", filename.c_str());
-                       h264_encoder->shutdown();
-                       httpd.close_output_file();
-                       httpd.open_output_file(filename.c_str());
-                       h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
+                       video_encoder->do_cut(frame);
                }
 
 #if 0
@@ -704,11 +655,21 @@ void Mixer::thread_func()
        resource_pool->clean_context();
 }
 
-void Mixer::get_one_frame_from_each_card(unsigned master_card_index, CaptureCard::NewFrame new_frames[MAX_CARDS], bool has_new_frame[MAX_CARDS], int num_samples[MAX_CARDS])
+void Mixer::get_one_frame_from_each_card(unsigned master_card_index, CaptureCard::NewFrame new_frames[MAX_VIDEO_CARDS], bool has_new_frame[MAX_VIDEO_CARDS], int num_samples[MAX_VIDEO_CARDS])
 {
+start:
        // The first card is the master timer, so wait for it to have a new frame.
+       // TODO: Add a timeout.
        unique_lock<mutex> lock(bmusb_mutex);
-       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].new_frames_changed.wait(lock, [this, master_card_index]{ return !cards[master_card_index].new_frames.empty() || cards[master_card_index].capture->get_disconnected(); });
+
+       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());
+               handle_hotplugged_cards();
+               goto start;
+       }
 
        for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
                CaptureCard *card = &cards[card_index];
@@ -743,18 +704,79 @@ void Mixer::get_one_frame_from_each_card(unsigned master_card_index, CaptureCard
        }
 }
 
+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) {
+               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(WIDTH, HEIGHT, FAKE_FPS, OUTPUT_FREQUENCY, card_index, global_flags.fake_cards_audio);
+                       configure_card(card_index, capture, /*is_fake_capture=*/true);
+                       card->queue_length_policy.reset(card_index);
+                       card->capture->start_bm_capture();
+               }
+       }
+
+       // Check for cards that have been connected since last frame.
+       vector<libusb_device *> hotplugged_cards_copy;
+       {
+               lock_guard<mutex> lock(hotplug_mutex);
+               swap(hotplugged_cards, hotplugged_cards_copy);
+       }
+       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) {
+                       if (cards[card_index].is_fake_capture) {
+                               free_card_index = int(card_index);
+                               break;
+                       }
+               }
+
+               if (free_card_index == -1) {
+                       fprintf(stderr, "New card plugged in, but no free slots -- ignoring.\n");
+                       libusb_unref_device(new_dev);
+               } else {
+                       // BMUSBCapture takes ownership.
+                       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, /*is_fake_capture=*/false);
+                       card->queue_length_policy.reset(free_card_index);
+                       capture->set_card_disconnected_callback(bind(&Mixer::bm_hotplug_remove, this, free_card_index));
+                       capture->start_bm_capture();
+               }
+       }
+}
+
+
 void Mixer::schedule_audio_resampling_tasks(unsigned dropped_frames, int num_samples_per_frame, int length_per_frame)
 {
        // 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);
                {
                        // Signal to the audio thread to process this frame.
+                       // Note that if the frame is a dropped frame, we signal that
+                       // we don't want to use this frame as base for adjusting
+                       // the resampler rate. The reason for this is that the timing
+                       // of these frames is often way too late; they typically don't
+                       // “arrive” before we synthesize them. Thus, we could end up
+                       // in a situation where we have inserted e.g. five audio frames
+                       // into the queue before we then start pulling five of them
+                       // back out. This makes ResamplingQueue overestimate the delay,
+                       // causing undue resampler changes. (We _do_ use the last,
+                       // non-dropped frame; perhaps we should just discard that as well,
+                       // since dropped frames are expected to be rare, and it might be
+                       // better to just wait until we have a slightly more normal situation).
                        unique_lock<mutex> lock(audio_mutex);
-                       audio_task_queue.push(AudioTask{pts_int, num_samples_per_frame});
+                       bool adjust_rate = !dropped_frame;
+                       audio_task_queue.push(AudioTask{pts_int, num_samples_per_frame, adjust_rate});
                        audio_task_queue_changed.notify_one();
                }
-               if (frame_num != dropped_frames) {
+               if (dropped_frame) {
                        // For dropped frames, increase the pts. Note that if the format changed
                        // in the meantime, we have no way of detecting that; we just have to
                        // assume the frame length is always the same.
@@ -763,7 +785,7 @@ void Mixer::schedule_audio_resampling_tasks(unsigned dropped_frames, int num_sam
        }
 }
 
-void Mixer::render_one_frame()
+void Mixer::render_one_frame(int64_t duration)
 {
        // Get the main chain from the theme, and set its state immediately.
        Theme::Chain theme_main_chain = theme->get_chain(0, pts(), WIDTH, HEIGHT, input_state);
@@ -772,7 +794,7 @@ void Mixer::render_one_frame()
        //theme_main_chain.chain->enable_phase_timing(true);
 
        GLuint y_tex, cbcr_tex;
-       bool got_frame = h264_encoder->begin_frame(&y_tex, &cbcr_tex);
+       bool got_frame = video_encoder->begin_frame(&y_tex, &cbcr_tex);
        assert(got_frame);
 
        // Render main chain.
@@ -793,11 +815,8 @@ void Mixer::render_one_frame()
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
-       RefCountedGLsync fence(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
-       check_error();
-
        const int64_t av_delay = TIMEBASE / 10;  // Corresponds to the fixed delay in resampling_queue.h. TODO: Make less hard-coded.
-       h264_encoder->end_frame(fence, pts_int + av_delay, theme_main_chain.input_frames);
+       RefCountedGLsync fence = video_encoder->end_frame(pts_int + av_delay, duration, theme_main_chain.input_frames);
 
        // The live frame just shows the RGBA texture we just rendered.
        // It owns rgba_tex now.
@@ -824,24 +843,6 @@ void Mixer::render_one_frame()
        }
 }
 
-void Mixer::send_audio_level_callback()
-{
-       if (audio_level_callback == nullptr) {
-               return;
-       }
-
-       unique_lock<mutex> lock(compressor_mutex);
-       double loudness_s = r128.loudness_S();
-       double loudness_i = r128.integrated();
-       double loudness_range_low = r128.range_min();
-       double loudness_range_high = r128.range_max();
-
-       audio_level_callback(loudness_s, 20.0 * log10(peak),
-               loudness_i, loudness_range_low, loudness_range_high,
-               gain_staging_db, 20.0 * log10(final_makeup_gain),
-               correlation.get_correlation());
-}
-
 void Mixer::audio_thread_func()
 {
        while (!should_quit) {
@@ -849,176 +850,27 @@ void Mixer::audio_thread_func()
 
                {
                        unique_lock<mutex> lock(audio_mutex);
-                       audio_task_queue_changed.wait(lock, [this]{ return !audio_task_queue.empty(); });
+                       audio_task_queue_changed.wait(lock, [this]{ return should_quit || !audio_task_queue.empty(); });
+                       if (should_quit) {
+                               return;
+                       }
                        task = audio_task_queue.front();
                        audio_task_queue.pop();
                }
 
-               process_audio_one_frame(task.pts_int, task.num_samples);
-       }
-}
-
-void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
-{
-       vector<float> samples_card;
-       vector<float> samples_out;
-
-       // TODO: Allow mixing audio from several sources.
-       unsigned selected_audio_card = theme->map_signal(audio_source_channel);
-       assert(selected_audio_card < num_cards);
-
-       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-               samples_card.resize(num_samples * 2);
-               {
-                       unique_lock<mutex> lock(cards[card_index].audio_mutex);
-                       if (!cards[card_index].resampling_queue->get_output_samples(double(frame_pts_int) / TIMEBASE, &samples_card[0], num_samples)) {
-                               printf("Card %d reported previous underrun.\n", card_index);
-                       }
-               }
-               if (card_index == selected_audio_card) {
-                       samples_out = move(samples_card);
-               }
-       }
-
-       // Cut away everything under 120 Hz (or whatever the cutoff is);
-       // we don't need it for voice, and it will reduce headroom
-       // and confuse the compressor. (In particular, any hums at 50 or 60 Hz
-       // should be dampened.)
-       if (locut_enabled) {
-               locut.render(samples_out.data(), samples_out.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
-       }
-
-       // Apply a level compressor to get the general level right.
-       // Basically, if it's over about -40 dBFS, we squeeze it down to that level
-       // (or more precisely, near it, since we don't use infinite ratio),
-       // then apply a makeup gain to get it to -14 dBFS. -14 dBFS is, of course,
-       // entirely arbitrary, but from practical tests with speech, it seems to
-       // put ut around -23 LUFS, so it's a reasonable starting point for later use.
-       {
-               unique_lock<mutex> lock(compressor_mutex);
-               if (level_compressor_enabled) {
-                       float threshold = 0.01f;   // -40 dBFS.
-                       float ratio = 20.0f;
-                       float attack_time = 0.5f;
-                       float release_time = 20.0f;
-                       float makeup_gain = pow(10.0f, (ref_level_dbfs - (-40.0f)) / 20.0f);  // +26 dB.
-                       level_compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
-                       gain_staging_db = 20.0 * log10(level_compressor.get_attenuation() * makeup_gain);
-               } else {
-                       // Just apply the gain we already had.
-                       float g = pow(10.0f, gain_staging_db / 20.0f);
-                       for (size_t i = 0; i < samples_out.size(); ++i) {
-                               samples_out[i] *= g;
-                       }
-               }
-       }
-
-#if 0
-       printf("level=%f (%+5.2f dBFS) attenuation=%f (%+5.2f dB) end_result=%+5.2f dB\n",
-               level_compressor.get_level(), 20.0 * log10(level_compressor.get_level()),
-               level_compressor.get_attenuation(), 20.0 * log10(level_compressor.get_attenuation()),
-               20.0 * log10(level_compressor.get_level() * level_compressor.get_attenuation() * makeup_gain));
-#endif
-
-//     float limiter_att, compressor_att;
-
-       // The real compressor.
-       if (compressor_enabled) {
-               float threshold = pow(10.0f, compressor_threshold_dbfs / 20.0f);
-               float ratio = 20.0f;
-               float attack_time = 0.005f;
-               float release_time = 0.040f;
-               float makeup_gain = 2.0f;  // +6 dB.
-               compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
-//             compressor_att = compressor.get_attenuation();
-       }
-
-       // Finally a limiter at -4 dB (so, -10 dBFS) to take out the worst peaks only.
-       // Note that since ratio is not infinite, we could go slightly higher than this.
-       if (limiter_enabled) {
-               float threshold = pow(10.0f, limiter_threshold_dbfs / 20.0f);
-               float ratio = 30.0f;
-               float attack_time = 0.0f;  // Instant.
-               float release_time = 0.020f;
-               float makeup_gain = 1.0f;  // 0 dB.
-               limiter.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
-//             limiter_att = limiter.get_attenuation();
-       }
-
-//     printf("limiter=%+5.1f  compressor=%+5.1f\n", 20.0*log10(limiter_att), 20.0*log10(compressor_att));
-
-       // Upsample 4x to find interpolated peak.
-       peak_resampler.inp_data = samples_out.data();
-       peak_resampler.inp_count = samples_out.size() / 2;
-
-       vector<float> interpolated_samples_out;
-       interpolated_samples_out.resize(samples_out.size());
-       while (peak_resampler.inp_count > 0) {  // About four iterations.
-               peak_resampler.out_data = &interpolated_samples_out[0];
-               peak_resampler.out_count = interpolated_samples_out.size() / 2;
-               peak_resampler.process();
-               size_t out_stereo_samples = interpolated_samples_out.size() / 2 - peak_resampler.out_count;
-               peak = max<float>(peak, find_peak(interpolated_samples_out.data(), out_stereo_samples * 2));
-               peak_resampler.out_data = nullptr;
-       }
-
-       // At this point, we are most likely close to +0 LU, but all of our
-       // measurements have been on raw sample values, not R128 values.
-       // So we have a final makeup gain to get us to +0 LU; the gain
-       // adjustments required should be relatively small, and also, the
-       // offset shouldn't change much (only if the type of audio changes
-       // significantly). Thus, we shoot for updating this value basically
-       // “whenever we process buffers”, since the R128 calculation isn't exactly
-       // something we get out per-sample.
-       //
-       // Note that there's a feedback loop here, so we choose a very slow filter
-       // (half-time of 100 seconds).
-       double target_loudness_factor, alpha;
-       {
-               unique_lock<mutex> lock(compressor_mutex);
-               double loudness_lu = r128.loudness_M() - ref_level_lufs;
-               double current_makeup_lu = 20.0f * log10(final_makeup_gain);
-               target_loudness_factor = pow(10.0f, -loudness_lu / 20.0f);
-
-               // If we're outside +/- 5 LU uncorrected, we don't count it as
-               // a normal signal (probably silence) and don't change the
-               // correction factor; just apply what we already have.
-               if (fabs(loudness_lu - current_makeup_lu) >= 5.0 || !final_makeup_gain_auto) {
-                       alpha = 0.0;
-               } else {
-                       // Formula adapted from
-                       // https://en.wikipedia.org/wiki/Low-pass_filter#Simple_infinite_impulse_response_filter.
-                       const double half_time_s = 100.0;
-                       const double fc_mul_2pi_delta_t = 1.0 / (half_time_s * OUTPUT_FREQUENCY);
-                       alpha = fc_mul_2pi_delta_t / (fc_mul_2pi_delta_t + 1.0);
-               }
+               ResamplingQueue::RateAdjustmentPolicy rate_adjustment_policy =
+                       task.adjust_rate ? ResamplingQueue::ADJUST_RATE : ResamplingQueue::DO_NOT_ADJUST_RATE;
+               vector<float> samples_out = audio_mixer.get_output(
+                       double(task.pts_int) / TIMEBASE,
+                       task.num_samples,
+                       rate_adjustment_policy);
 
-               double m = final_makeup_gain;
-               for (size_t i = 0; i < samples_out.size(); i += 2) {
-                       samples_out[i + 0] *= m;
-                       samples_out[i + 1] *= m;
-                       m += (target_loudness_factor - m) * alpha;
+               // Send the samples to the sound card, then add them to the output.
+               if (alsa) {
+                       alsa->write(samples_out);
                }
-               final_makeup_gain = m;
+               video_encoder->add_audio(task.pts_int, move(samples_out));
        }
-
-       // Find R128 levels and L/R correlation.
-       vector<float> left, right;
-       deinterleave_samples(samples_out, &left, &right);
-       float *ptrs[] = { left.data(), right.data() };
-       {
-               unique_lock<mutex> lock(compressor_mutex);
-               r128.process(left.size(), ptrs);
-               correlation.process_samples(samples_out);
-       }
-
-       // Send the samples to the sound card.
-       if (alsa) {
-               alsa->write(samples_out);
-       }
-
-       // And finally add them to the output.
-       h264_encoder->add_audio(frame_pts_int, move(samples_out));
 }
 
 void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
@@ -1099,6 +951,7 @@ void Mixer::start()
 void Mixer::quit()
 {
        should_quit = true;
+       audio_task_queue_changed.notify_one();
        mixer_thread.join();
        audio_thread.join();
 }
@@ -1113,15 +966,6 @@ void Mixer::channel_clicked(int preview_num)
        theme->channel_clicked(preview_num);
 }
 
-void Mixer::reset_meters()
-{
-       peak_resampler.reset();
-       peak = 0.0f;
-       r128.reset();
-       r128.integr_start();
-       correlation.reset();
-}
-
 void Mixer::start_mode_scanning(unsigned card_index)
 {
        assert(card_index < num_cards);
@@ -1136,7 +980,7 @@ void Mixer::start_mode_scanning(unsigned card_index)
        assert(!mode_scanlist[card_index].empty());
        mode_scanlist_index[card_index] = 0;
        cards[card_index].capture->set_video_mode(mode_scanlist[card_index][0]);
-       clock_gettime(CLOCK_MONOTONIC, &last_mode_scan_change[card_index]);
+       last_mode_scan_change[card_index] = steady_clock::now();
 }
 
 Mixer::OutputChannel::~OutputChannel()
@@ -1162,9 +1006,47 @@ void Mixer::OutputChannel::output_frame(DisplayFrame frame)
                has_ready_frame = true;
        }
 
-       if (has_new_frame_ready_callback) {
+       if (new_frame_ready_callback) {
                new_frame_ready_callback();
        }
+
+       // Reduce the number of callbacks by filtering duplicates. The reason
+       // why we bother doing this is that Qt seemingly can get into a state
+       // where its builds up an essentially unbounded queue of signals,
+       // consuming more and more memory, and there's no good way of collapsing
+       // user-defined signals or limiting the length of the queue.
+       if (transition_names_updated_callback) {
+               vector<string> transition_names = global_mixer->get_transition_names();
+               bool changed = false;
+               if (transition_names.size() != last_transition_names.size()) {
+                       changed = true;
+               } else {
+                       for (unsigned i = 0; i < transition_names.size(); ++i) {
+                               if (transition_names[i] != last_transition_names[i]) {
+                                       changed = true;
+                                       break;
+                               }
+                       }
+               }
+               if (changed) {
+                       transition_names_updated_callback(transition_names);
+                       last_transition_names = transition_names;
+               }
+       }
+       if (name_updated_callback) {
+               string name = global_mixer->get_channel_name(channel);
+               if (name != last_name) {
+                       name_updated_callback(name);
+                       last_name = name;
+               }
+       }
+       if (color_updated_callback) {
+               string color = global_mixer->get_channel_color(channel);
+               if (color != last_color) {
+                       color_updated_callback(color);
+                       last_color = color;
+               }
+       }
 }
 
 bool Mixer::OutputChannel::get_display_frame(DisplayFrame *frame)
@@ -1195,5 +1077,21 @@ bool Mixer::OutputChannel::get_display_frame(DisplayFrame *frame)
 void Mixer::OutputChannel::set_frame_ready_callback(Mixer::new_frame_ready_callback_t callback)
 {
        new_frame_ready_callback = callback;
-       has_new_frame_ready_callback = true;
 }
+
+void Mixer::OutputChannel::set_transition_names_updated_callback(Mixer::transition_names_updated_callback_t callback)
+{
+       transition_names_updated_callback = callback;
+}
+
+void Mixer::OutputChannel::set_name_updated_callback(Mixer::name_updated_callback_t callback)
+{
+       name_updated_callback = callback;
+}
+
+void Mixer::OutputChannel::set_color_updated_callback(Mixer::color_updated_callback_t callback)
+{
+       color_updated_callback = callback;
+}
+
+mutex RefCountedGLsync::fence_lock;