]> git.sesse.net Git - nageru/blobdiff - mixer.cpp
Pull the file muxing out of the HTTPD. (It was pretty ugly all along.)
[nageru] / mixer.cpp
index 6ea3be3d0d2822edccaed984a3b56c8a98dc5485..3dc8a4c3e5c3630965106755c38f6e4a1373c865 100644 (file)
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -1,25 +1,21 @@
-#define WIDTH 1280
-#define HEIGHT 720
-#define EXTRAHEIGHT 30
-
 #undef Success
 
 #include "mixer.h"
 
 #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 <stdio.h>
 #include <stdlib.h>
 #include <sys/time.h>
 #include <time.h>
-#include <util.h>
 #include <algorithm>
 #include <cmath>
 #include <condition_variable>
 #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 "flags.h"
 #include "h264encode.h"
 #include "pbo_frame_allocator.h"
 #include "ref_counted_gl_sync.h"
@@ -51,6 +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++;
@@ -63,13 +63,87 @@ 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) {
+               for (unsigned frame_num = FRAME_HISTORY_LENGTH; frame_num --> 1; ) {  // :-)
+                       input_state->buffered_frames[card_index][frame_num] =
+                               input_state->buffered_frames[card_index][frame_num - 1];
+               }
+               input_state->buffered_frames[card_index][0] = { frame, field_num };
+       } else {
+               for (unsigned frame_num = 0; frame_num < FRAME_HISTORY_LENGTH; ++frame_num) {
+                       input_state->buffered_frames[card_index][frame_num] = { frame, field_num };
+               }
+       }
+}
+
+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)
+{
+       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(WIDTH, HEIGHT),
          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)
@@ -84,7 +158,7 @@ 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;
        }
@@ -102,61 +176,102 @@ 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));
+       h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
+       h264_encoder->open_output_file(generate_local_dump_filename(/*frame=*/0).c_str());
 
-       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(WIDTH * (HEIGHT+EXTRAHEIGHT) * 2 + 44, WIDTH, HEIGHT));
-               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();
+       // 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;
 
-       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-               cards[card_index].usb->start_bm_capture();
+       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();
        }
 
-       //chain->enable_phase_timing(true);
+       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";
-       cbcr_program_num = resource_pool->compile_glsl_program(cbcr_vert_shader, cbcr_frag_shader);
+       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));
 }
@@ -164,18 +279,48 @@ 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);
 }
 
+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)
@@ -192,7 +337,7 @@ 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;
 }
@@ -215,15 +360,38 @@ 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];
 
-       if (audio_frame.len - audio_offset > 30000) {
+       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;
+                       }
+               }
+       }
+
+       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) / 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);
                }
@@ -233,58 +401,77 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                return;
        }
 
-       int unwrapped_timecode = timecode;
+       int64_t local_pts = card->next_local_pts;
        int dropped_frames = 0;
        if (card->last_timecode != -1) {
-               unwrapped_timecode = unwrap_timecode(unwrapped_timecode, card->last_timecode);
-               dropped_frames = unwrapped_timecode - card->last_timecode - 1;
+               dropped_frames = unwrap_timecode(timecode, card->last_timecode) - card->last_timecode - 1;
        }
-       card->last_timecode = unwrapped_timecode;
 
        // Convert the audio to stereo fp32 and add it.
-       size_t num_samples = (audio_frame.len >= audio_offset) ? (audio_frame.len - audio_offset) / 8 / 3 : 0;
        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.
        {
                unique_lock<mutex> lock(card->audio_mutex);
 
-               int unwrapped_timecode = timecode;
-               if (dropped_frames > FPS * 2) {
-                       fprintf(stderr, "Card %d lost more than two seconds (or time code jumping around), resetting resampler\n",
-                               card_index);
+               // 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.resize((OUTPUT_FREQUENCY / FPS) * 2);
+                       vector<float> silence(silence_samples * 2, 0.0f);
                        for (int i = 0; i < dropped_frames; ++i) {
-                               card->resampling_queue->add_input_samples((unwrapped_timecode - dropped_frames + i) / double(FPS), silence.data(), (OUTPUT_FREQUENCY / FPS));
+                               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;
                        }
                }
-               card->resampling_queue->add_input_samples(unwrapped_timecode / double(FPS), audio.data(), num_samples);
+               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;
        }
 
+       card->last_timecode = timecode;
+
        // Done with the audio, so release it.
        if (audio_frame.owner) {
                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;
-       }
-
-       if (video_frame.len - video_offset != WIDTH * (HEIGHT+EXTRAHEIGHT) * 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) {
-                       printf("Card %d: Dropping video frame with wrong length (%ld)\n",
-                               card_index, video_frame.len - video_offset);
+                       printf("Card %d: Dropping video frame with wrong length (%ld; expected %ld)\n",
+                               card_index, video_frame.len - video_offset, expected_length);
                }
                if (video_frame.owner) {
                        video_frame.owner->release_frame(video_frame);
@@ -294,47 +481,128 @@ 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_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;
        }
 
-       const PBOFrameAllocator::Userdata *userdata = (const PBOFrameAllocator::Userdata *)video_frame.userdata;
-       GLuint pbo = userdata->pbo;
-       check_error();
-       glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo);
-       check_error();
-       glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, video_frame.size);
-       check_error();
-       //glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
-       //check_error();
+       PBOFrameAllocator::Userdata *userdata = (PBOFrameAllocator::Userdata *)video_frame.userdata;
+
+       unsigned num_fields = video_format.interlaced ? 2 : 1;
+       timespec 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.
+               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 = 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.
-       glBindTexture(GL_TEXTURE_2D, userdata->tex_y);
-       check_error();
-       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, WIDTH, HEIGHT, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET((WIDTH * (HEIGHT+EXTRAHEIGHT) * 2 + 44) / 2 + WIDTH * 25 + 22));
-       check_error();
-       glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr);
-       check_error();
-       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, WIDTH/2, HEIGHT, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(WIDTH * 25 + 22));
-       check_error();
-       glBindTexture(GL_TEXTURE_2D, 0);
-       check_error();
-       GLsync fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);              
-       check_error();
-       assert(fence != nullptr);
+       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) ? 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;
+               }
 
-       {
-               unique_lock<mutex> lock(bmusb_mutex);
-               card->new_data_ready = true;
-               card->new_frame = RefCountedFrame(video_frame);
-               card->new_data_ready_fence = fence;
-               card->dropped_frames = dropped_frames;
-               card->new_data_ready_changed.notify_all();
+               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();
+               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, 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();
+               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();
+
+               if (field == 1) {
+                       // Don't upload the second field as fast as we can; wait until
+                       // the field time has approximately passed. (Otherwise, we could
+                       // get timing jitter against the other sources, and possibly also
+                       // 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) ;
+               }
+
+               {
+                       unique_lock<mutex> lock(bmusb_mutex);
+                       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();
+               }
        }
 }
 
@@ -351,170 +619,85 @@ void Mixer::thread_func()
        clock_gettime(CLOCK_MONOTONIC, &start);
 
        int frame = 0;
-       int dropped_frames = 0;
+       int stats_dropped_frames = 0;
 
        while (!should_quit) {
-               CaptureCard card_copy[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_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();
-                       }
-               }
+               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) {
-                       process_audio_one_frame();
-                       if (frame_num != card_copy[0].dropped_frames) {
-                               // For dropped frames, increase the pts.
-                               ++dropped_frames;
-                               pts_int += TIMEBASE / FPS;
+               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) {
-                       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) {
-                       ++dropped_frames;
-                       pts_int += TIMEBASE / FPS;
+               if (new_frames[master_card_index].frame->len == 0) {
+                       ++stats_dropped_frames;
+                       pts_int += new_frames[master_card_index].length;
                        continue;
                }
 
                for (unsigned card_index = 0; card_index < num_cards; ++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);
-                       bmusb_current_rendering_frame[card_index] = card->new_frame;
+                       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();
                        }
-                       const PBOFrameAllocator::Userdata *userdata = (const PBOFrameAllocator::Userdata *)card->new_frame->userdata;
-                       theme->set_input_textures(card_index, userdata->tex_y, userdata->tex_cbcr);
                }
 
-               // Get the main chain from the theme, and set its state immediately.
-               pair<EffectChain *, function<void()>> theme_main_chain = theme->get_chain(0, pts(), WIDTH, HEIGHT);
-               EffectChain *chain = theme_main_chain.first;
-               theme_main_chain.second();
-
-               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();
-
-               // Make sure the H.264 gets a reference to all the
-               // input frames needed, so that they are not released back
-               // until the rendering is done.
-               vector<RefCountedFrame> input_frames;
-               for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-                       input_frames.push_back(bmusb_current_rendering_frame[card_index]);
-               }
-               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, input_frames);
+               render_one_frame();
                ++frame;
-               pts_int += TIMEBASE / FPS;
-
-               // 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;
-                       pair<EffectChain *, function<void()>> chain = theme->get_chain(i, pts(), WIDTH, HEIGHT);  // FIXME: dimensions
-                       display_frame.chain = chain.first;
-                       display_frame.setup_chain = chain.second;
-                       display_frame.ready_fence = fence;
-
-                       // FIXME: possible to do better?
-                       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-                               display_frame.input_frames.push_back(bmusb_current_rendering_frame[card_index]);
-                       }
-                       display_frame.temp_textures = {};
-                       output_channel[i].output_frame(display_frame);
-               }
+               pts_int += new_frames[master_card_index].length;
 
                clock_gettime(CLOCK_MONOTONIC, &now);
                double elapsed = now.tv_sec - start.tv_sec +
                        1e-9 * (now.tv_nsec - start.tv_nsec);
                if (frame % 100 == 0) {
                        printf("%d frames (%d dropped) in %.3f seconds = %.1f fps (%.1f ms/frame)\n",
-                               frame, dropped_frames, elapsed, frame / elapsed,
+                               frame, stats_dropped_frames, elapsed, frame / elapsed,
                                1e3 * elapsed / frame);
                //      chain->print_phase_timing();
                }
 
+               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->close_output_file();
+                       h264_encoder->shutdown();
+                       h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
+                       h264_encoder->open_output_file(filename.c_str());
+               }
+
 #if 0
                // Reset every 100 frames, so that local variations in frame times
                // (especially for the first few frames, when the shaders are
@@ -531,28 +714,186 @@ void Mixer::thread_func()
        resource_pool->clean_context();
 }
 
-void Mixer::process_audio_one_frame()
+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()
+{
+       // 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);
+
+       const int64_t av_delay = TIMEBASE / 10;  // Corresponds to the fixed delay in resampling_queue.h. TODO: Make less hard-coded.
+       RefCountedGLsync fence = h264_encoder->end_frame(pts_int + av_delay, 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) {
+               AudioTask task;
+
+               {
+                       unique_lock<mutex> lock(audio_mutex);
+                       audio_task_queue_changed.wait(lock, [this]{ return !audio_task_queue.empty(); });
+                       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((OUTPUT_FREQUENCY / FPS) * 2);
+               samples_card.resize(num_samples * 2);
                {
                        unique_lock<mutex> lock(cards[card_index].audio_mutex);
-                       if (!cards[card_index].resampling_queue->get_output_samples(pts(), &samples_card[0], OUTPUT_FREQUENCY / FPS)) {
+                       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);
                        }
                }
-               // 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);
                }
        }
 
-       // Cut away everything under 150 Hz; 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);
+       // 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
@@ -560,15 +901,23 @@ void Mixer::process_audio_one_frame()
        // 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
@@ -617,13 +966,58 @@ void Mixer::process_audio_one_frame()
                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() };
-       r128.process(left.size(), ptrs);
+       {
+               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) {
@@ -631,7 +1025,7 @@ void Mixer::process_audio_one_frame()
        }
 
        // And finally add them to the output.
-       h264_encoder->add_audio(pts_int, move(samples_out));
+       h264_encoder->add_audio(frame_pts_int, move(samples_out));
 }
 
 void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
@@ -640,12 +1034,6 @@ 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();
 
@@ -672,17 +1060,28 @@ 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);
@@ -701,12 +1100,14 @@ void Mixer::release_display_frame(DisplayFrame *frame)
 void Mixer::start()
 {
        mixer_thread = thread(&Mixer::thread_func, this);
+       audio_thread = thread(&Mixer::audio_thread_func, this);
 }
 
 void Mixer::quit()
 {
        should_quit = true;
        mixer_thread.join();
+       audio_thread.join();
 }
 
 void Mixer::transition_clicked(int transition_num)
@@ -725,6 +1126,24 @@ 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()