]> git.sesse.net Git - nageru/blobdiff - mixer.cpp
Start pulling video orchestration logic into VideoEncoder.
[nageru] / mixer.cpp
index 61050067b7b9dd60c652a855336eea54f68dec9d..dc9eea63fc0473f99d9260bffb8c99bb10aa485d 100644 (file)
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -4,11 +4,11 @@
 
 #include <assert.h>
 #include <epoxy/egl.h>
-#include <init.h>
 #include <movit/effect_chain.h>
 #include <movit/effect_util.h>
 #include <movit/flat_input.h>
 #include <movit/image_format.h>
+#include <movit/init.h>
 #include <movit/resource_pool.h>
 #include <movit/util.h>
 #include <stdint.h>
 #include <thread>
 #include <utility>
 #include <vector>
+#include <arpa/inet.h>
 
 #include "bmusb/bmusb.h"
 #include "context.h"
+#include "decklink_capture.h"
 #include "defs.h"
-#include "h264encode.h"
+#include "flags.h"
+#include "video_encoder.h"
 #include "pbo_frame_allocator.h"
 #include "ref_counted_gl_sync.h"
 #include "timebase.h"
@@ -47,6 +50,7 @@ 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++;
@@ -59,6 +63,20 @@ void convert_fixed24_to_fp32(float *dst, size_t out_channels, const uint8_t *src
        }
 }
 
+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) {
@@ -76,17 +94,43 @@ void insert_new_frame(RefCountedFrame frame, unsigned field_num, bool interlaced
 
 }  // namespace
 
+void QueueLengthPolicy::update_policy(int queue_length)
+{
+       if (queue_length < 0) {  // Starvation.
+               if (been_at_safe_point_since_last_starvation && safe_queue_length < 5) {
+                       ++safe_queue_length;
+                       fprintf(stderr, "Card %u: Starvation, increasing safe limit to %u frames\n",
+                               card_index, safe_queue_length);
+               }
+               frames_with_at_least_one = 0;
+               been_at_safe_point_since_last_starvation = false;
+               return;
+       }
+       if (queue_length > 0) {
+               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) {
+                       --safe_queue_length;
+                       fprintf(stderr, "Card %u: Spare frames for more than 50 frames, reducing safe limit to %u frames\n",
+                               card_index, safe_queue_length);
+                       frames_with_at_least_one = 0;
+               }
+       } else {
+               frames_with_at_least_one = 0;
+       }
+}
+
 Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
-       : httpd(LOCAL_DUMP_FILE_NAME, 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)
 {
-       httpd.start(9095);
-
        CHECK(init_movit(MOVIT_SHADER_DIR, MOVIT_DEBUG_OFF));
        check_error();
 
@@ -95,7 +139,7 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        movit_texel_subpixel_precision /= 2.0;
 
        resource_pool.reset(new ResourcePool);
-       theme.reset(new Theme("theme.lua", resource_pool.get(), num_cards));
+       theme.reset(new Theme(global_flags.theme_filename.c_str(), resource_pool.get(), num_cards));
        for (unsigned i = 0; i < NUM_OUTPUTS; ++i) {
                output_channel[i].parent = this;
        }
@@ -113,60 +157,104 @@ 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, WIDTH, HEIGHT, &httpd));
+       video_encoder.reset(new VideoEncoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
 
-       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-               printf("Configuring card %d...\n", card_index);
-               CaptureCard *card = &cards[card_index];
-               card->usb = new BMUSBCapture(card_index);
-               card->usb->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.
-               card->usb->set_video_frame_allocator(card->frame_allocator.get());
-               card->surface = create_surface(format);
-               card->usb->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));
-               card->usb->configure_card();
-       }
-
-       BMUSBCapture::start_bm_thread();
+       // Start listening for clients only once VideoEncoder has written its header, if any.
+       httpd.start(9095);
 
-       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-               cards[card_index].usb->start_bm_capture();
+       // 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;
+       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;
+                       }
+
+                       configure_card(card_index, format, new DeckLinkCapture(decklink, card_index));
+                       ++num_pci_devices;
+               }
+               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;
+       }
+
+       if (num_usb_devices > 0) {
+               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();
        }
 
        // Set up stuff for NV12 conversion.
 
        // Cb/Cr shader.
-       string cbcr_vert_shader = read_file("vs-cbcr.130.vert");
+       string cbcr_vert_shader =
+               "#version 130 \n"
+               " \n"
+               "in vec2 position; \n"
+               "in vec2 texcoord; \n"
+               "out vec2 tc0; \n"
+               "uniform vec2 foo_chroma_offset_0; \n"
+               " \n"
+               "void main() \n"
+               "{ \n"
+               "    // The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is: \n"
+               "    // \n"
+               "    //   2.000  0.000  0.000 -1.000 \n"
+               "    //   0.000  2.000  0.000 -1.000 \n"
+               "    //   0.000  0.000 -2.000 -1.000 \n"
+               "    //   0.000  0.000  0.000  1.000 \n"
+               "    gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0); \n"
+               "    vec2 flipped_tc = texcoord; \n"
+               "    tc0 = flipped_tc + foo_chroma_offset_0; \n"
+               "} \n";
        string cbcr_frag_shader =
                "#version 130 \n"
                "in vec2 tc0; \n"
                "uniform sampler2D cbcr_tex; \n"
+               "out vec4 FragColor; \n"
                "void main() { \n"
-               "    gl_FragColor = texture2D(cbcr_tex, tc0); \n"
+               "    FragColor = texture(cbcr_tex, tc0); \n"
                "} \n";
        vector<string> frag_shader_outputs;
        cbcr_program_num = resource_pool->compile_glsl_program(cbcr_vert_shader, cbcr_frag_shader, frag_shader_outputs);
 
+       float vertices[] = {
+               0.0f, 2.0f,
+               0.0f, 0.0f,
+               2.0f, 0.0f
+       };
+       cbcr_vbo = generate_vbo(2, GL_FLOAT, sizeof(vertices), vertices);
+       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);
+       }
+
        // 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);
+       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));
 }
@@ -174,20 +262,48 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
 Mixer::~Mixer()
 {
        resource_pool->release_glsl_program(cbcr_program_num);
+       glDeleteBuffers(1, &cbcr_vbo);
        BMUSBCapture::stop_bm_thread();
 
        for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
                {
                        unique_lock<mutex> lock(bmusb_mutex);
                        cards[card_index].should_quit = true;  // Unblock thread.
-                       cards[card_index].new_data_ready_changed.notify_all();
+                       cards[card_index].new_frames_changed.notify_all();
                }
-               cards[card_index].usb->stop_dequeue_thread();
+               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)
+{
+       printf("Configuring card %d...\n", card_index);
+
+       CaptureCard *card = &cards[card_index];
+       card->capture = 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.
+       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));
+       card->capture->configure_card();
+}
+
+
 namespace {
 
 int unwrap_timecode(uint16_t current_wrapped, int last)
@@ -204,7 +320,7 @@ 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 = std::max(m, fabs(samples[i]));
+               m = max(m, fabs(samples[i]));
        }
        return m;
 }
@@ -227,23 +343,38 @@ void deinterleave_samples(const vector<float> &in, vector<float> *out_l, vector<
 }  // namespace
 
 void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
-                     FrameAllocator::Frame video_frame, size_t video_offset, uint16_t video_format,
-                    FrameAllocator::Frame audio_frame, size_t audio_offset, uint16_t audio_format)
+                     FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
+                    FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)
 {
        CaptureCard *card = &cards[card_index];
 
-       unsigned width, height, second_field_start, frame_rate_nom, frame_rate_den, extra_lines_top, extra_lines_bottom;
-       bool interlaced;
+       if (is_mode_scanning[card_index]) {
+               if (video_format.has_signal) {
+                       // Found a stable signal, so stop scanning.
+                       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);
+                       if (sec_since_last_switch > switch_time_s) {
+                               // It isn't this mode; try the next one.
+                               mode_scanlist_index[card_index]++;
+                               mode_scanlist_index[card_index] %= mode_scanlist[card_index].size();
+                               cards[card_index].capture->set_video_mode(mode_scanlist[card_index][mode_scanlist_index[card_index]]);
+                               last_mode_scan_change[card_index] = now;
+                       }
+               }
+       }
 
-       decode_video_format(video_format, &width, &height, &second_field_start, &extra_lines_top, &extra_lines_bottom,
-                           &frame_rate_nom, &frame_rate_den, &interlaced);  // Ignore return value for now.
-       int64_t frame_length = TIMEBASE * frame_rate_den / frame_rate_nom;
+       int64_t frame_length = int64_t(TIMEBASE * video_format.frame_rate_den) / video_format.frame_rate_nom;
 
-       size_t num_samples = (audio_frame.len >= audio_offset) ? (audio_frame.len - audio_offset) / 8 / 3 : 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) {
                printf("Card %d: Dropping frame with implausible audio length (len=%d, offset=%d) [timecode=0x%04x video_len=%d video_offset=%d video_format=%x)\n",
                        card_index, int(audio_frame.len), int(audio_offset),
-                       timecode, int(video_frame.len), int(video_offset), video_format);
+                       timecode, int(video_frame.len), int(video_offset), video_format.id);
                if (video_frame.owner) {
                        video_frame.owner->release_frame(video_frame);
                }
@@ -262,7 +393,20 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        // Convert the audio to stereo fp32 and add it.
        vector<float> audio;
        audio.resize(num_samples * 2);
-       convert_fixed24_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, 8, num_samples);
+       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.
        {
@@ -270,7 +414,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
                // 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 * frame_rate_den / frame_rate_nom;
+               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",
@@ -305,14 +449,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                audio_frame.owner->release_frame(audio_frame);
        }
 
-       {
-               // Wait until the previous frame was consumed.
-               unique_lock<mutex> lock(bmusb_mutex);
-               card->new_data_ready_changed.wait(lock, [card]{ return !card->new_data_ready || card->should_quit; });
-               if (card->should_quit) return;
-       }
-
-       size_t expected_length = width * (height + extra_lines_top + extra_lines_bottom) * 2;
+       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) {
                if (video_frame.len != 0) {
@@ -327,83 +464,96 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                // so that pts can go up accordingly.
                {
                        unique_lock<mutex> lock(bmusb_mutex);
-                       card->new_data_ready = true;
-                       card->new_frame = RefCountedFrame(FrameAllocator::Frame());
-                       card->new_frame_length = frame_length;
-                       card->new_frame_interlaced = false;
-                       card->new_data_ready_fence = nullptr;
-                       card->dropped_frames = dropped_frames;
-                       card->new_data_ready_changed.notify_all();
+                       CaptureCard::NewFrame new_frame;
+                       new_frame.frame = RefCountedFrame(FrameAllocator::Frame());
+                       new_frame.length = frame_length;
+                       new_frame.interlaced = false;
+                       new_frame.dropped_frames = dropped_frames;
+                       card->new_frames.push(move(new_frame));
+                       card->new_frames_changed.notify_all();
                }
                return;
        }
 
        PBOFrameAllocator::Userdata *userdata = (PBOFrameAllocator::Userdata *)video_frame.userdata;
 
-       unsigned num_fields = interlaced ? 2 : 1;
+       unsigned num_fields = video_format.interlaced ? 2 : 1;
        timespec frame_upload_start;
-       if (interlaced) {
+       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(height % 2 == 0);
-               height /= 2;
+               assert(video_format.height % 2 == 0);
+               video_format.height /= 2;
                assert(frame_length % 2 == 0);
                frame_length /= 2;
                num_fields = 2;
                clock_gettime(CLOCK_MONOTONIC, &frame_upload_start);
        }
-       userdata->last_interlaced = interlaced;
-       userdata->last_frame_rate_nom = frame_rate_nom;
-       userdata->last_frame_rate_den = frame_rate_den;
-       RefCountedFrame new_frame(video_frame);
+       userdata->last_interlaced = video_format.interlaced;
+       userdata->last_has_signal = video_format.has_signal;
+       userdata->last_frame_rate_nom = video_format.frame_rate_nom;
+       userdata->last_frame_rate_den = video_format.frame_rate_den;
+       RefCountedFrame frame(video_frame);
 
        // Upload the textures.
-       size_t cbcr_width = width / 2;
+       size_t cbcr_width = video_format.width / 2;
        size_t cbcr_offset = video_offset / 2;
        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) ? second_field_start : extra_lines_top + field * (height + 22);
+               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 ||
-                   width != userdata->last_width[field] ||
-                   height != userdata->last_height[field]) {
+                   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, height, 0, GL_RG, GL_UNSIGNED_BYTE, nullptr);
+                       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, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
+                       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] = width;
-                       userdata->last_height[field] = height;
+                       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_ARB, pbo);
-               check_error();
-               glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
+               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();
-               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, cbcr_width, height, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(cbcr_offset + cbcr_width * field_start_line * sizeof(uint16_t)));
+               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();
-               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(y_offset + width * field_start_line));
+               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();
                glBindTexture(GL_TEXTURE_2D, 0);
                check_error();
-               GLsync fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
+               glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+               check_error();
+               RefCountedGLsync fence(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
+               check_error();
+               assert(fence.get() != nullptr);
+               glFlush();  // Make sure the main thread doesn't have to wait until we push out enough frames to make a new command buffer.
                check_error();
-               assert(fence != nullptr);
 
                if (field == 1) {
                        // Don't upload the second field as fast as we can; wait until
@@ -426,20 +576,15 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
                {
                        unique_lock<mutex> lock(bmusb_mutex);
-                       card->new_data_ready = true;
-                       card->new_frame = new_frame;
-                       card->new_frame_length = frame_length;
-                       card->new_frame_field = field;
-                       card->new_frame_interlaced = interlaced;
-                       card->new_data_ready_fence = fence;
-                       card->dropped_frames = dropped_frames;
-                       card->new_data_ready_changed.notify_all();
-
-                       if (field != num_fields - 1) {
-                               // Wait until the previous frame was consumed.
-                               card->new_data_ready_changed.wait(lock, [card]{ return !card->new_data_ready || card->should_quit; });
-                               if (card->should_quit) return;
-                       }
+                       CaptureCard::NewFrame new_frame;
+                       new_frame.frame = frame;
+                       new_frame.length = frame_length;
+                       new_frame.field = field;
+                       new_frame.interlaced = video_format.interlaced;
+                       new_frame.ready_fence = fence;
+                       new_frame.dropped_frames = dropped_frames;
+                       card->new_frames.push(move(new_frame));
+                       card->new_frames_changed.notify_all();
                }
        }
 }
@@ -460,161 +605,63 @@ void Mixer::thread_func()
        int stats_dropped_frames = 0;
 
        while (!should_quit) {
-               CaptureCard card_copy[MAX_CARDS];
-               int num_samples[MAX_CARDS];
+               CaptureCard::NewFrame new_frames[MAX_CARDS];
+               bool has_new_frame[MAX_CARDS] = { false };
+               int num_samples[MAX_CARDS] = { 0 };
 
-               {
-                       unique_lock<mutex> lock(bmusb_mutex);
+               // TODO: Add a timeout.
+               unsigned master_card_index = theme->map_signal(master_clock_channel);
+               assert(master_card_index < num_cards);
 
-                       // The first card is the master timer, so wait for it to have a new frame.
-                       // TODO: Make configurable, and with a timeout.
-                       cards[0].new_data_ready_changed.wait(lock, [this]{ return cards[0].new_data_ready; });
-
-                       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-                               CaptureCard *card = &cards[card_index];
-                               card_copy[card_index].usb = card->usb;
-                               card_copy[card_index].new_data_ready = card->new_data_ready;
-                               card_copy[card_index].new_frame = card->new_frame;
-                               card_copy[card_index].new_frame_length = card->new_frame_length;
-                               card_copy[card_index].new_frame_field = card->new_frame_field;
-                               card_copy[card_index].new_frame_interlaced = card->new_frame_interlaced;
-                               card_copy[card_index].new_data_ready_fence = card->new_data_ready_fence;
-                               card_copy[card_index].dropped_frames = card->dropped_frames;
-                               card->new_data_ready = false;
-                               card->new_data_ready_changed.notify_all();
-
-                               int num_samples_times_timebase = OUTPUT_FREQUENCY * card->new_frame_length + card->fractional_samples;
-                               num_samples[card_index] = num_samples_times_timebase / TIMEBASE;
-                               card->fractional_samples = num_samples_times_timebase % TIMEBASE;
-                               assert(num_samples[card_index] >= 0);
-                       }
-               }
+               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();
 
-               // Resample the audio as needed, including from previously dropped frames.
-               for (unsigned frame_num = 0; frame_num < card_copy[0].dropped_frames + 1; ++frame_num) {
-                       {
-                               // Signal to the audio thread to process this frame.
-                               unique_lock<mutex> lock(audio_mutex);
-                               audio_task_queue.push(AudioTask{pts_int, num_samples[0]});
-                               audio_task_queue_changed.notify_one();
-                       }
-                       if (frame_num != card_copy[0].dropped_frames) {
-                               // 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.
-                               ++stats_dropped_frames;
-                               pts_int += card_copy[0].new_frame_length;
+               for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
+                       if (card_index == master_card_index || !has_new_frame[card_index]) {
+                               continue;
                        }
-               }
-
-               if (audio_level_callback != nullptr) {
-                       unique_lock<mutex> lock(r128_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,
-                                            last_gain_staging_db);
-               }
-
-               for (unsigned card_index = 1; card_index < num_cards; ++card_index) {
-                       if (card_copy[card_index].new_data_ready && card_copy[card_index].new_frame->len == 0) {
-                               ++card_copy[card_index].dropped_frames;
+                       if (new_frames[card_index].frame->len == 0) {
+                               ++new_frames[card_index].dropped_frames;
                        }
-                       if (card_copy[card_index].dropped_frames > 0) {
+                       if (new_frames[card_index].dropped_frames > 0) {
                                printf("Card %u dropped %d frames before this\n",
-                                       card_index, int(card_copy[card_index].dropped_frames));
+                                       card_index, 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 (card_copy[0].new_frame->len == 0) {
+               if (new_frames[master_card_index].frame->len == 0) {
                        ++stats_dropped_frames;
-                       pts_int += card_copy[0].new_frame_length;
+                       pts_int += new_frames[master_card_index].length;
                        continue;
                }
 
                for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-                       CaptureCard *card = &card_copy[card_index];
-                       if (!card->new_data_ready || card->new_frame->len == 0)
+                       if (!has_new_frame[card_index] || new_frames[card_index].frame->len == 0)
                                continue;
 
-                       assert(card->new_frame != nullptr);
-                       insert_new_frame(card->new_frame, card->new_frame_field, card->new_frame_interlaced, card_index, &input_state);
+                       CaptureCard::NewFrame *new_frame = &new_frames[card_index];
+                       assert(new_frame->frame != nullptr);
+                       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 (card->new_data_ready_fence) {
-                               glWaitSync(card->new_data_ready_fence, /*flags=*/0, GL_TIMEOUT_IGNORED);
+                       if (new_frame->ready_fence) {
+                               glWaitSync(new_frame->ready_fence.get(), /*flags=*/0, GL_TIMEOUT_IGNORED);
                                check_error();
-                               glDeleteSync(card->new_data_ready_fence);
+                               new_frame->ready_fence.reset();
                                check_error();
                        }
                }
 
-               // 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);
-               EffectChain *chain = theme_main_chain.chain;
-               theme_main_chain.setup_chain();
-               //theme_main_chain.chain->enable_phase_timing(true);
-
-               GLuint y_tex, cbcr_tex;
-               bool got_frame = h264_encoder->begin_frame(&y_tex, &cbcr_tex);
-               assert(got_frame);
-
-               // Render main chain.
-               GLuint cbcr_full_tex = resource_pool->create_2d_texture(GL_RG8, WIDTH, HEIGHT);
-               GLuint rgba_tex = resource_pool->create_2d_texture(GL_RGB565, WIDTH, HEIGHT);  // Saves texture bandwidth, although dithering gets messed up.
-               GLuint fbo = resource_pool->create_fbo(y_tex, cbcr_full_tex, rgba_tex);
-               check_error();
-               chain->render_to_fbo(fbo, WIDTH, HEIGHT);
-               resource_pool->release_fbo(fbo);
-
-               subsample_chroma(cbcr_full_tex, cbcr_tex);
-               resource_pool->release_2d_texture(cbcr_full_tex);
-
-               // Set the right state for rgba_tex.
-               glBindFramebuffer(GL_FRAMEBUFFER, 0);
-               glBindTexture(GL_TEXTURE_2D, rgba_tex);
-               glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-               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);
+               int64_t duration = new_frames[master_card_index].length;
+               render_one_frame(duration);
                ++frame;
-               pts_int += card_copy[0].new_frame_length;
-
-               // The live frame just shows the RGBA texture we just rendered.
-               // It owns rgba_tex now.
-               DisplayFrame live_frame;
-               live_frame.chain = display_chain.get();
-               live_frame.setup_chain = [this, rgba_tex]{
-                       display_input->set_texture_num(rgba_tex);
-               };
-               live_frame.ready_fence = fence;
-               live_frame.input_frames = {};
-               live_frame.temp_textures = { rgba_tex };
-               output_channel[OUTPUT_LIVE].output_frame(live_frame);
-
-               // Set up preview and any additional channels.
-               for (int i = 1; i < theme->get_num_channels() + 2; ++i) {
-                       DisplayFrame display_frame;
-                       Theme::Chain chain = theme->get_chain(i, pts(), WIDTH, HEIGHT, input_state);  // FIXME: dimensions
-                       display_frame.chain = chain.chain;
-                       display_frame.setup_chain = chain.setup_chain;
-                       display_frame.ready_fence = fence;
-                       display_frame.input_frames = chain.input_frames;
-                       display_frame.temp_textures = {};
-                       output_channel[i].output_frame(display_frame);
-               }
+               pts_int += duration;
 
                clock_gettime(CLOCK_MONOTONIC, &now);
                double elapsed = now.tv_sec - start.tv_sec +
@@ -626,6 +673,10 @@ void Mixer::thread_func()
                //      chain->print_phase_timing();
                }
 
+               if (should_cut.exchange(false)) {  // Test and clear.
+                       video_encoder->do_cut(frame);
+               }
+
 #if 0
                // Reset every 100 frames, so that local variations in frame times
                // (especially for the first few frames, when the shaders are
@@ -642,6 +693,141 @@ 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])
+{
+       // The first card is the master timer, so wait for it to have a new frame.
+       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(); });
+
+       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
+               CaptureCard *card = &cards[card_index];
+               if (card->new_frames.empty()) {
+                       assert(card_index != master_card_index);
+                       card->queue_length_policy.update_policy(-1);
+                       continue;
+               }
+               new_frames[card_index] = move(card->new_frames.front());
+               has_new_frame[card_index] = true;
+               card->new_frames.pop();
+               card->new_frames_changed.notify_all();
+
+               int num_samples_times_timebase = OUTPUT_FREQUENCY * new_frames[card_index].length + card->fractional_samples;
+               num_samples[card_index] = num_samples_times_timebase / TIMEBASE;
+               card->fractional_samples = num_samples_times_timebase % TIMEBASE;
+               assert(num_samples[card_index] >= 0);
+
+               if (card_index == master_card_index) {
+                       // We don't use the queue length policy for the master card,
+                       // but we will if it stops being the master. Thus, clear out
+                       // the policy in case we switch in the future.
+                       card->queue_length_policy.reset(card_index);
+               } else {
+                       // If we have excess frames compared to the policy for this card,
+                       // drop frames from the head.
+                       card->queue_length_policy.update_policy(card->new_frames.size());
+                       while (card->new_frames.size() > card->queue_length_policy.get_safe_queue_length()) {
+                               card->new_frames.pop();
+                       }
+               }
+       }
+}
+
+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) {
+               {
+                       // Signal to the audio thread to process this frame.
+                       unique_lock<mutex> lock(audio_mutex);
+                       audio_task_queue.push(AudioTask{pts_int, num_samples_per_frame});
+                       audio_task_queue_changed.notify_one();
+               }
+               if (frame_num != dropped_frames) {
+                       // 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.
+                       pts_int += length_per_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);
+       EffectChain *chain = theme_main_chain.chain;
+       theme_main_chain.setup_chain();
+       //theme_main_chain.chain->enable_phase_timing(true);
+
+       GLuint y_tex, cbcr_tex;
+       bool got_frame = video_encoder->begin_frame(&y_tex, &cbcr_tex);
+       assert(got_frame);
+
+       // Render main chain.
+       GLuint cbcr_full_tex = resource_pool->create_2d_texture(GL_RG8, WIDTH, HEIGHT);
+       GLuint rgba_tex = resource_pool->create_2d_texture(GL_RGB565, WIDTH, HEIGHT);  // Saves texture bandwidth, although dithering gets messed up.
+       GLuint fbo = resource_pool->create_fbo(y_tex, cbcr_full_tex, rgba_tex);
+       check_error();
+       chain->render_to_fbo(fbo, WIDTH, HEIGHT);
+       resource_pool->release_fbo(fbo);
+
+       subsample_chroma(cbcr_full_tex, cbcr_tex);
+       resource_pool->release_2d_texture(cbcr_full_tex);
+
+       // Set the right state for rgba_tex.
+       glBindFramebuffer(GL_FRAMEBUFFER, 0);
+       glBindTexture(GL_TEXTURE_2D, rgba_tex);
+       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+       const int64_t av_delay = TIMEBASE / 10;  // Corresponds to the fixed delay in resampling_queue.h. TODO: Make less hard-coded.
+       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.
+       DisplayFrame live_frame;
+       live_frame.chain = display_chain.get();
+       live_frame.setup_chain = [this, rgba_tex]{
+               display_input->set_texture_num(rgba_tex);
+       };
+       live_frame.ready_fence = fence;
+       live_frame.input_frames = {};
+       live_frame.temp_textures = { rgba_tex };
+       output_channel[OUTPUT_LIVE].output_frame(live_frame);
+
+       // Set up preview and any additional channels.
+       for (int i = 1; i < theme->get_num_channels() + 2; ++i) {
+               DisplayFrame display_frame;
+               Theme::Chain chain = theme->get_chain(i, pts(), WIDTH, HEIGHT, input_state);  // FIXME: dimensions
+               display_frame.chain = chain.chain;
+               display_frame.setup_chain = chain.setup_chain;
+               display_frame.ready_fence = fence;
+               display_frame.input_frames = chain.input_frames;
+               display_frame.temp_textures = {};
+               output_channel[i].output_frame(display_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) {
@@ -662,6 +848,11 @@ 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);
                {
@@ -670,8 +861,7 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
                                printf("Card %d reported previous underrun.\n", card_index);
                        }
                }
-               // TODO: Allow using audio from the other card(s) as well.
-               if (card_index == 0) {
+               if (card_index == selected_audio_card) {
                        samples_out = move(samples_card);
                }
        }
@@ -680,7 +870,9 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
        // 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.)
-       locut.render(samples_out.data(), samples_out.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
+       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
@@ -688,15 +880,23 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
        // 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.
-       float ref_level_dbfs = -14.0f;
        {
-               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);
-               last_gain_staging_db = 20.0 * log10(level_compressor.get_attenuation() * makeup_gain);
+               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
@@ -745,15 +945,57 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
                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);
+               }
+
+               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;
+               }
+               final_makeup_gain = m;
        }
 
-       // Find R128 levels.
+       // 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(r128_mutex);
+               unique_lock<mutex> lock(compressor_mutex);
                r128.process(left.size(), ptrs);
+               correlation.process_samples(samples_out);
        }
 
        // Send the samples to the sound card.
@@ -762,7 +1004,7 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
        }
 
        // And finally add them to the output.
-       h264_encoder->add_audio(frame_pts_int, move(samples_out));
+       video_encoder->add_audio(frame_pts_int, move(samples_out));
 }
 
 void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
@@ -771,12 +1013,6 @@ void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
        glGenVertexArrays(1, &vao);
        check_error();
 
-       float vertices[] = {
-               0.0f, 2.0f,
-               0.0f, 0.0f,
-               2.0f, 0.0f
-       };
-
        glBindVertexArray(vao);
        check_error();
 
@@ -803,17 +1039,28 @@ void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
        float chroma_offset_0[] = { -0.5f / WIDTH, 0.0f };
        set_uniform_vec2(cbcr_program_num, "foo", "chroma_offset_0", chroma_offset_0);
 
-       GLuint position_vbo = fill_vertex_attribute(cbcr_program_num, "position", 2, GL_FLOAT, sizeof(vertices), vertices);
-       GLuint texcoord_vbo = fill_vertex_attribute(cbcr_program_num, "texcoord", 2, GL_FLOAT, sizeof(vertices), vertices);  // Same as vertices.
+       glBindBuffer(GL_ARRAY_BUFFER, cbcr_vbo);
+       check_error();
+
+       for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
+               glEnableVertexAttribArray(attr_index);
+               check_error();
+               glVertexAttribPointer(attr_index, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
+               check_error();
+       }
 
        glDrawArrays(GL_TRIANGLES, 0, 3);
        check_error();
 
-       cleanup_vertex_attribute(cbcr_program_num, "position", position_vbo);
-       cleanup_vertex_attribute(cbcr_program_num, "texcoord", texcoord_vbo);
+       for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
+               glDisableVertexAttribArray(attr_index);
+               check_error();
+       }
 
        glUseProgram(0);
        check_error();
+       glBindFramebuffer(GL_FRAMEBUFFER, 0);
+       check_error();
 
        resource_pool->release_fbo(fbo);
        glDeleteVertexArrays(1, &vao);
@@ -858,6 +1105,24 @@ void Mixer::reset_meters()
        peak = 0.0f;
        r128.reset();
        r128.integr_start();
+       correlation.reset();
+}
+
+void Mixer::start_mode_scanning(unsigned card_index)
+{
+       assert(card_index < num_cards);
+       if (is_mode_scanning[card_index]) {
+               return;
+       }
+       is_mode_scanning[card_index] = true;
+       mode_scanlist[card_index].clear();
+       for (const auto &mode : cards[card_index].capture->get_available_video_modes()) {
+               mode_scanlist[card_index].push_back(mode.first);
+       }
+       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]);
 }
 
 Mixer::OutputChannel::~OutputChannel()
@@ -918,3 +1183,5 @@ void Mixer::OutputChannel::set_frame_ready_callback(Mixer::new_frame_ready_callb
        new_frame_ready_callback = callback;
        has_new_frame_ready_callback = true;
 }
+
+mutex RefCountedGLsync::fence_lock;