]> git.sesse.net Git - nageru/blobdiff - mixer.cpp
Support switching Y'CbCr coefficients midway, which will allow doing the Right Thing...
[nageru] / mixer.cpp
index 0a657276be068af0694fd5bfd288b32e4cb276b7..898e7c04cef19e52e6060720b71bcab1a4769f38 100644 (file)
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -45,6 +45,8 @@
 #include "ref_counted_gl_sync.h"
 #include "resampling_queue.h"
 #include "timebase.h"
+#include "timecode_renderer.h"
+#include "v210_converter.h"
 #include "video_encoder.h"
 
 class IDeckLink;
@@ -76,31 +78,101 @@ void insert_new_frame(RefCountedFrame frame, unsigned field_num, bool interlaced
        }
 }
 
+void ensure_texture_resolution(PBOFrameAllocator::Userdata *userdata, unsigned field, unsigned width, unsigned height, unsigned v210_width)
+{
+       bool first;
+       if (global_flags.ten_bit_input) {
+               first = userdata->tex_v210[field] == 0 || userdata->tex_444[field] == 0;
+       } else {
+               first = userdata->tex_y[field] == 0 || userdata->tex_cbcr[field] == 0;
+       }
+
+       if (first ||
+           width != userdata->last_width[field] ||
+           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.
+               if (global_flags.ten_bit_input) {
+                       glBindTexture(GL_TEXTURE_2D, userdata->tex_444[field]);
+                       check_error();
+                       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB10_A2, width, height, 0, GL_RGBA, GL_UNSIGNED_INT_2_10_10_10_REV, nullptr);
+                       check_error();
+               } else {
+                       size_t cbcr_width = width / 2;
+
+                       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);
+                       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);
+                       check_error();
+               }
+               userdata->last_width[field] = width;
+               userdata->last_height[field] = height;
+       }
+       if (global_flags.ten_bit_input &&
+           (first || v210_width != userdata->last_v210_width[field])) {
+               // Same as above; we need to recreate the texture.
+               glBindTexture(GL_TEXTURE_2D, userdata->tex_v210[field]);
+               check_error();
+               glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB10_A2, v210_width, height, 0, GL_RGBA, GL_UNSIGNED_INT_2_10_10_10_REV, nullptr);
+               check_error();
+               userdata->last_v210_width[field] = v210_width;
+       }
+}
+
+void upload_texture(GLuint tex, GLuint width, GLuint height, GLuint stride, bool interlaced_stride, GLenum format, GLenum type, GLintptr offset)
+{
+       if (interlaced_stride) {
+               stride *= 2;
+       }
+       if (global_flags.flush_pbos) {
+               glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, offset, stride * height);
+               check_error();
+       }
+
+       glBindTexture(GL_TEXTURE_2D, tex);
+       check_error();
+       if (interlaced_stride) {
+               glPixelStorei(GL_UNPACK_ROW_LENGTH, width * 2);
+               check_error();
+       } else {
+               glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+               check_error();
+       }
+
+       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, format, type, BUFFER_OFFSET(offset));
+       check_error();
+       glBindTexture(GL_TEXTURE_2D, 0);
+       check_error();
+       glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+       check_error();
+}
+
 }  // namespace
 
-void QueueLengthPolicy::update_policy(int queue_length)
+void QueueLengthPolicy::update_policy(unsigned queue_length)
 {
-       if (queue_length < 0) {  // Starvation.
-               if (been_at_safe_point_since_last_starvation && safe_queue_length < 5) {
+       if (queue_length == 0) {  // Starvation.
+               if (been_at_safe_point_since_last_starvation && safe_queue_length < unsigned(global_flags.max_input_queue_frames)) {
                        ++safe_queue_length;
-                       fprintf(stderr, "Card %u: Starvation, increasing safe limit to %u frames\n",
+                       fprintf(stderr, "Card %u: Starvation, increasing safe limit to %u frame(s)\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 >= 1000 && safe_queue_length > 0) {
-                       --safe_queue_length;
-                       fprintf(stderr, "Card %u: Spare frames for more than 1000 frames, reducing safe limit to %u frames\n",
-                               card_index, safe_queue_length);
-                       frames_with_at_least_one = 0;
-               }
-       } else {
+       if (queue_length >= safe_queue_length) {
+               been_at_safe_point_since_last_starvation = true;
+       }
+       if (++frames_with_at_least_one >= 1000 && safe_queue_length > 1) {
+               --safe_queue_length;
+               fprintf(stderr, "Card %u: Spare frames for more than 1000 frames, reducing safe limit to %u frame(s)\n",
+                       card_index, safe_queue_length);
                frames_with_at_least_one = 0;
        }
 }
@@ -131,10 +203,26 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        inout_format.color_space = COLORSPACE_sRGB;
        inout_format.gamma_curve = GAMMA_sRGB;
 
-       // Display chain; shows the live output produced by the main chain (its RGBA version).
+       // Matches the 4:2:0 format created by the main chain.
+       YCbCrFormat ycbcr_format;
+       ycbcr_format.chroma_subsampling_x = 2;
+       ycbcr_format.chroma_subsampling_y = 2;
+       if (global_flags.ycbcr_rec709_coefficients) {
+               ycbcr_format.luma_coefficients = YCBCR_REC_709;
+       } else {
+               ycbcr_format.luma_coefficients = YCBCR_REC_601;
+       }
+       ycbcr_format.full_range = false;
+       ycbcr_format.num_levels = 256;
+       ycbcr_format.cb_x_position = 0.0f;
+       ycbcr_format.cr_x_position = 0.0f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_y_position = 0.5f;
+
+       // Display chain; shows the live output produced by the main chain (or rather, a copy of it).
        display_chain.reset(new EffectChain(global_flags.width, global_flags.height, resource_pool.get()));
        check_error();
-       display_input = new FlatInput(inout_format, FORMAT_RGB, GL_UNSIGNED_BYTE, global_flags.width, global_flags.height);  // FIXME: GL_UNSIGNED_BYTE is really wrong.
+       display_input = new YCbCrInput(inout_format, ycbcr_format, global_flags.width, global_flags.height, YCBCR_INPUT_SPLIT_Y_AND_CBCR);
        display_chain->add_input(display_input);
        display_chain->add_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED);
        display_chain->set_dither_bits(0);  // Don't bother.
@@ -199,6 +287,28 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
 
        chroma_subsampler.reset(new ChromaSubsampler(resource_pool.get()));
 
+       if (global_flags.ten_bit_input) {
+               if (!v210Converter::has_hardware_support()) {
+                       fprintf(stderr, "ERROR: --ten-bit-input requires support for OpenGL compute shaders\n");
+                       fprintf(stderr, "       (OpenGL 4.3, or GL_ARB_compute_shader + GL_ARB_shader_image_load_store).\n");
+                       exit(1);
+               }
+               v210_converter.reset(new v210Converter());
+
+               // These are all the widths listed in the Blackmagic SDK documentation
+               // (section 2.7.3, “Display Modes”).
+               v210_converter->precompile_shader(720);
+               v210_converter->precompile_shader(1280);
+               v210_converter->precompile_shader(1920);
+               v210_converter->precompile_shader(2048);
+               v210_converter->precompile_shader(3840);
+               v210_converter->precompile_shader(4096);
+       }
+
+       timecode_renderer.reset(new TimecodeRenderer(resource_pool.get(), global_flags.width, global_flags.height));
+       display_timecode_in_stream = global_flags.display_timecode_in_stream;
+       display_timecode_on_stdout = global_flags.display_timecode_on_stdout;
+
        if (global_flags.enable_alsa_output) {
                alsa.reset(new ALSAOutput(OUTPUT_FREQUENCY, /*num_channels=*/2));
        }
@@ -249,8 +359,9 @@ void Mixer::configure_card(unsigned card_index, CaptureInterface *capture, bool
        if (card->surface == nullptr) {
                card->surface = create_surface_with_same_format(mixer_surface);
        }
-       while (!card->new_frames.empty()) card->new_frames.pop();
+       while (!card->new_frames.empty()) card->new_frames.pop_front();
        card->last_timecode = -1;
+       card->capture->set_pixel_format(global_flags.ten_bit_input ? PixelFormat_10BitYCbCr : PixelFormat_8BitYCbCr);
        card->capture->configure_card();
 
        // NOTE: start_bm_capture() happens in thread_func().
@@ -297,7 +408,8 @@ void Mixer::set_output_card_internal(int card_index)
                configure_card(card_index, fake_capture, /*is_fake_capture=*/true, card->output.release());
                card->queue_length_policy.reset(card_index);
                card->capture->start_bm_capture();
-               card->output->start_output(bmdModeHD720p5994, pts_int);  // FIXME
+               desired_output_video_mode = output_video_mode = card->output->pick_video_mode(desired_output_video_mode);
+               card->output->start_output(desired_output_video_mode, pts_int);
        }
        output_card_index = card_index;
 }
@@ -383,7 +495,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                } while (!success);
        }
 
-       audio_mixer.add_audio(device, audio_frame.data + audio_offset, num_samples, audio_format, frame_length);
+       audio_mixer.add_audio(device, audio_frame.data + audio_offset, num_samples, audio_format, frame_length, audio_frame.received_timestamp);
 
        // Done with the audio, so release it.
        if (audio_frame.owner) {
@@ -392,7 +504,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
        card->last_timecode = timecode;
 
-       size_t expected_length = video_format.width * (video_format.height + video_format.extra_lines_top + video_format.extra_lines_bottom) * 2;
+       size_t expected_length = video_format.stride * (video_format.height + video_format.extra_lines_top + video_format.extra_lines_bottom);
        if (video_frame.len - video_offset == 0 ||
            video_frame.len - video_offset != expected_length) {
                if (video_frame.len != 0) {
@@ -412,7 +524,8 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                        new_frame.length = frame_length;
                        new_frame.interlaced = false;
                        new_frame.dropped_frames = dropped_frames;
-                       card->new_frames.push(move(new_frame));
+                       new_frame.received_timestamp = video_frame.received_timestamp;
+                       card->new_frames.push_back(move(new_frame));
                        card->new_frames_changed.notify_all();
                }
                return;
@@ -444,9 +557,9 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        RefCountedFrame frame(video_frame);
 
        // Upload the textures.
-       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;
+       const size_t cbcr_width = video_format.width / 2;
+       const size_t cbcr_offset = video_offset / 2;
+       const size_t y_offset = video_frame.size / 2 + video_offset / 2;
 
        for (unsigned field = 0; field < num_fields; ++field) {
                // Put the actual texture upload in a lambda that is executed in the main thread.
@@ -457,7 +570,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                // Note that this means we must hold on to the actual frame data in <userdata>
                // until the upload command is run, but we hold on to <frame> much longer than that
                // (in fact, all the way until we no longer use the texture in rendering).
-               auto upload_func = [field, video_format, y_offset, cbcr_offset, cbcr_width, interlaced_stride, userdata]() {
+               auto upload_func = [this, field, video_format, y_offset, video_offset, cbcr_offset, cbcr_width, interlaced_stride, userdata]() {
                        unsigned field_start_line;
                        if (field == 1) {
                                field_start_line = video_format.second_field_start;
@@ -465,68 +578,28 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                                field_start_line = video_format.extra_lines_top;
                        }
 
-                       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;
-                       }
+                       // For 8-bit input, v210_width will be nonsensical but not used.
+                       size_t v210_width = video_format.stride / sizeof(uint32_t);
+                       ensure_texture_resolution(userdata, field, video_format.width, video_format.height, v210_width);
 
-                       GLuint pbo = userdata->pbo;
-                       check_error();
-                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo);
+                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER, userdata->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.ten_bit_input) {
+                               size_t field_start = video_offset + video_format.stride * field_start_line;
+                               upload_texture(userdata->tex_v210[field], v210_width, video_format.height, video_format.stride, interlaced_stride, GL_RGBA, GL_UNSIGNED_INT_2_10_10_10_REV, field_start);
+                               v210_converter->convert(userdata->tex_v210[field], userdata->tex_444[field], video_format.width, video_format.height);
+                       } else {
+                               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();
+                               // Make up our own strides, since we are interleaving.
+                               upload_texture(userdata->tex_y[field], video_format.width, video_format.height, video_format.width, interlaced_stride, GL_RED, GL_UNSIGNED_BYTE, field_y_start);
+                               upload_texture(userdata->tex_cbcr[field], cbcr_width, video_format.height, cbcr_width * sizeof(uint16_t), interlaced_stride, GL_RG, GL_UNSIGNED_BYTE, field_cbcr_start);
                        }
 
-                       glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
-                       check_error();
-                       if (interlaced_stride) {
-                               glPixelStorei(GL_UNPACK_ROW_LENGTH, cbcr_width * 2);
-                               check_error();
-                       } else {
-                               glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
-                               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();
-                       if (interlaced_stride) {
-                               glPixelStorei(GL_UNPACK_ROW_LENGTH, video_format.width * 2);
-                               check_error();
-                       } else {
-                               glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
-                               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();
-                       glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
-                       check_error();
                };
 
                if (field == 1) {
@@ -551,7 +624,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                        new_frame.upload_func = upload_func;
                        new_frame.dropped_frames = dropped_frames;
                        new_frame.received_timestamp = video_frame.received_timestamp;  // Ignore the audio timestamp.
-                       card->new_frames.push(move(new_frame));
+                       card->new_frames.push_back(move(new_frame));
                        card->new_frames_changed.notify_all();
                }
        }
@@ -590,13 +663,19 @@ void Mixer::thread_func()
        steady_clock::time_point start, now;
        start = steady_clock::now();
 
-       int frame = 0;
        int stats_dropped_frames = 0;
 
        while (!should_quit) {
                if (desired_output_card_index != output_card_index) {
                        set_output_card_internal(desired_output_card_index);
                }
+               if (output_card_index != -1 &&
+                   desired_output_video_mode != output_video_mode) {
+                       DeckLinkOutput *output = cards[output_card_index].output.get();
+                       output->end_output();
+                       desired_output_video_mode = output_video_mode = output->pick_video_mode(desired_output_video_mode);
+                       output->start_output(desired_output_video_mode, pts_int);
+               }
 
                CaptureCard::NewFrame new_frames[MAX_VIDEO_CARDS];
                bool has_new_frame[MAX_VIDEO_CARDS] = { false };
@@ -613,7 +692,7 @@ void Mixer::thread_func()
                }
 
                OutputFrameInfo output_frame_info = get_one_frame_from_each_card(master_card_index, master_card_is_output, new_frames, has_new_frame);
-               schedule_audio_resampling_tasks(output_frame_info.dropped_frames, output_frame_info.num_samples, output_frame_info.frame_duration);
+               schedule_audio_resampling_tasks(output_frame_info.dropped_frames, output_frame_info.num_samples, output_frame_info.frame_duration, output_frame_info.is_preroll, output_frame_info.frame_timestamp);
                stats_dropped_frames += output_frame_info.dropped_frames;
 
                handle_hotplugged_cards();
@@ -657,15 +736,15 @@ void Mixer::thread_func()
 
                int64_t frame_duration = output_frame_info.frame_duration;
                render_one_frame(frame_duration);
-               ++frame;
+               ++frame_num;
                pts_int += frame_duration;
 
                now = steady_clock::now();
                double elapsed = duration<double>(now - start).count();
-               if (frame % 100 == 0) {
+               if (frame_num % 100 == 0) {
                        printf("%d frames (%d dropped) in %.3f seconds = %.1f fps (%.1f ms/frame)",
-                               frame, stats_dropped_frames, elapsed, frame / elapsed,
-                               1e3 * elapsed / frame);
+                               frame_num, stats_dropped_frames, elapsed, frame_num / elapsed,
+                               1e3 * elapsed / frame_num);
                //      chain->print_phase_timing();
 
                        // Check our memory usage, to see if we are close to our mlockall()
@@ -702,7 +781,7 @@ void Mixer::thread_func()
 
 
                if (should_cut.exchange(false)) {  // Test and clear.
-                       video_encoder->do_cut(frame);
+                       video_encoder->do_cut(frame_num);
                }
 
 #if 0
@@ -731,6 +810,47 @@ bool Mixer::input_card_is_master_clock(unsigned card_index, unsigned master_card
        return (card_index == master_card_index);
 }
 
+void Mixer::trim_queue(CaptureCard *card, unsigned card_index)
+{
+       // Count the number of frames in the queue, including any frames
+       // we dropped. It's hard to know exactly how we should deal with
+       // dropped (corrupted) input frames; they don't help our goal of
+       // avoiding starvation, but they still add to the problem of latency.
+       // Since dropped frames is going to mean a bump in the signal anyway,
+       // we err on the side of having more stable latency instead.
+       unsigned queue_length = 0;
+       for (const CaptureCard::NewFrame &frame : card->new_frames) {
+               queue_length += frame.dropped_frames + 1;
+       }
+       card->queue_length_policy.update_policy(queue_length);
+
+       // If needed, drop frames until the queue is below the safe limit.
+       // We prefer to drop from the head, because all else being equal,
+       // we'd like more recent frames (less latency).
+       unsigned dropped_frames = 0;
+       while (queue_length > card->queue_length_policy.get_safe_queue_length()) {
+               assert(!card->new_frames.empty());
+               assert(queue_length > card->new_frames.front().dropped_frames);
+               queue_length -= card->new_frames.front().dropped_frames;
+
+               if (queue_length <= card->queue_length_policy.get_safe_queue_length()) {
+                       // No need to drop anything.
+                       break;
+               }
+
+               card->new_frames.pop_front();
+               card->new_frames_changed.notify_all();
+               --queue_length;
+               ++dropped_frames;
+       }
+
+       if (dropped_frames > 0) {
+               fprintf(stderr, "Card %u dropped %u frame(s) to keep latency down.\n",
+                       card_index, dropped_frames);
+       }
+}
+
+
 Mixer::OutputFrameInfo Mixer::get_one_frame_from_each_card(unsigned master_card_index, bool master_card_is_output, CaptureCard::NewFrame new_frames[MAX_VIDEO_CARDS], bool has_new_frame[MAX_VIDEO_CARDS])
 {
        OutputFrameInfo output_frame_info;
@@ -738,11 +858,12 @@ start:
        unique_lock<mutex> lock(card_mutex, defer_lock);
        if (master_card_is_output) {
                // Clocked to the output, so wait for it to be ready for the next frame.
-               cards[master_card_index].output->wait_for_frame(pts_int, &output_frame_info.dropped_frames, &output_frame_info.frame_duration);
+               cards[master_card_index].output->wait_for_frame(pts_int, &output_frame_info.dropped_frames, &output_frame_info.frame_duration, &output_frame_info.is_preroll, &output_frame_info.frame_timestamp);
                lock.lock();
        } else {
                // Wait for the master card to have a new frame.
                // TODO: Add a timeout.
+               output_frame_info.is_preroll = false;
                lock.lock();
                cards[master_card_index].new_frames_changed.wait(lock, [this, master_card_index]{ return !cards[master_card_index].new_frames.empty() || cards[master_card_index].capture->get_disconnected(); });
        }
@@ -757,30 +878,27 @@ start:
                goto start;
        }
 
+       if (!master_card_is_output) {
+               output_frame_info.frame_timestamp =
+                       cards[master_card_index].new_frames.front().received_timestamp;
+       }
+
        for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
                CaptureCard *card = &cards[card_index];
-               if (card->new_frames.empty()) {
-                       assert(!input_card_is_master_clock(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();
-
                if (input_card_is_master_clock(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);
+                       assert(!card->new_frames.empty());
                } 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();
-                       }
+                       trim_queue(card, card_index);
+               }
+               if (!card->new_frames.empty()) {
+                       new_frames[card_index] = move(card->new_frames.front());
+                       has_new_frame[card_index] = true;
+                       card->new_frames.pop_front();
+                       card->new_frames_changed.notify_all();
                }
        }
 
@@ -846,7 +964,7 @@ void Mixer::handle_hotplugged_cards()
 }
 
 
-void Mixer::schedule_audio_resampling_tasks(unsigned dropped_frames, int num_samples_per_frame, int length_per_frame)
+void Mixer::schedule_audio_resampling_tasks(unsigned dropped_frames, int num_samples_per_frame, int length_per_frame, bool is_preroll, steady_clock::time_point frame_timestamp)
 {
        // Resample the audio as needed, including from previously dropped frames.
        assert(num_cards > 0);
@@ -867,8 +985,8 @@ void Mixer::schedule_audio_resampling_tasks(unsigned dropped_frames, int num_sam
                        // since dropped frames are expected to be rare, and it might be
                        // better to just wait until we have a slightly more normal situation).
                        unique_lock<mutex> lock(audio_mutex);
-                       bool adjust_rate = !dropped_frame;
-                       audio_task_queue.push(AudioTask{pts_int, num_samples_per_frame, adjust_rate});
+                       bool adjust_rate = !dropped_frame && !is_preroll;
+                       audio_task_queue.push(AudioTask{pts_int, num_samples_per_frame, adjust_rate, frame_timestamp});
                        audio_task_queue_changed.notify_one();
                }
                if (dropped_frame) {
@@ -882,50 +1000,93 @@ void Mixer::schedule_audio_resampling_tasks(unsigned dropped_frames, int num_sam
 
 void Mixer::render_one_frame(int64_t duration)
 {
+       // Determine the time code for this frame before we start rendering.
+       string timecode_text = timecode_renderer->get_timecode_text(double(pts_int) / TIMEBASE, frame_num);
+       if (display_timecode_on_stdout) {
+               printf("Timecode: '%s'\n", timecode_text.c_str());
+       }
+
        // Get the main chain from the theme, and set its state immediately.
        Theme::Chain theme_main_chain = theme->get_chain(0, pts(), global_flags.width, global_flags.height, input_state);
        EffectChain *chain = theme_main_chain.chain;
        theme_main_chain.setup_chain();
        //theme_main_chain.chain->enable_phase_timing(true);
 
+       // If HDMI/SDI output is active and the user has requested auto mode,
+       // its mode overrides the existing Y'CbCr setting for the chain.
+       YCbCrLumaCoefficients ycbcr_output_coefficients;
+       if (global_flags.ycbcr_auto_coefficients && output_card_index != -1) {
+               ycbcr_output_coefficients = cards[output_card_index].output->preferred_ycbcr_coefficients();
+       } else {
+               ycbcr_output_coefficients = global_flags.ycbcr_rec709_coefficients ? YCBCR_REC_709 : YCBCR_REC_601;
+       }
+
+       // TODO: Reduce the duplication against theme.cpp.
+       YCbCrFormat output_ycbcr_format;
+       output_ycbcr_format.chroma_subsampling_x = 1;
+       output_ycbcr_format.chroma_subsampling_y = 1;
+       output_ycbcr_format.luma_coefficients = ycbcr_output_coefficients;
+       output_ycbcr_format.full_range = false;
+       output_ycbcr_format.num_levels = 256;
+       chain->change_ycbcr_output_format(output_ycbcr_format);
+
+       const int64_t av_delay = lrint(global_flags.audio_queue_length_ms * 0.001 * TIMEBASE);  // Corresponds to the delay in ResamplingQueue.
        GLuint y_tex, cbcr_tex;
-       bool got_frame = video_encoder->begin_frame(&y_tex, &cbcr_tex);
+       bool got_frame = video_encoder->begin_frame(pts_int + av_delay, duration, ycbcr_output_coefficients, theme_main_chain.input_frames, &y_tex, &cbcr_tex);
        assert(got_frame);
 
-       // Render main chain.
+       // Render main chain. We take an extra copy of the created outputs,
+       // so that we can display it back to the screen later (it's less memory
+       // bandwidth than writing and reading back an RGBA texture, even at 16-bit).
+       // Ideally, we'd like to avoid taking copies and just use the main textures
+       // for display as well, but if they're used for zero-copy Quick Sync encoding
+       // (the default case), they're just views into VA-API memory and must be
+       // unmapped during encoding, so we can't use them for display, unfortunately.
        GLuint cbcr_full_tex = resource_pool->create_2d_texture(GL_RG8, global_flags.width, global_flags.height);
-       GLuint rgba_tex = resource_pool->create_2d_texture(GL_RGB565, global_flags.width, global_flags.height);  // Saves texture bandwidth, although dithering gets messed up.
-       GLuint fbo = resource_pool->create_fbo(y_tex, cbcr_full_tex, rgba_tex);
+       GLuint y_copy_tex = resource_pool->create_2d_texture(GL_R8, global_flags.width, global_flags.height);
+       GLuint fbo = resource_pool->create_fbo(y_tex, cbcr_full_tex, y_copy_tex);
        check_error();
        chain->render_to_fbo(fbo, global_flags.width, global_flags.height);
+
+       if (display_timecode_in_stream) {
+               // Render the timecode on top.
+               timecode_renderer->render_timecode(fbo, timecode_text);
+       }
+
        resource_pool->release_fbo(fbo);
 
-       chroma_subsampler->subsample_chroma(cbcr_full_tex, global_flags.width, global_flags.height, cbcr_tex);
+       GLuint cbcr_copy_tex = resource_pool->create_2d_texture(GL_RG8, global_flags.width / 2, global_flags.height / 2);
+       chroma_subsampler->subsample_chroma(cbcr_full_tex, global_flags.width, global_flags.height, cbcr_tex, cbcr_copy_tex);
        if (output_card_index != -1) {
-               cards[output_card_index].output->send_frame(y_tex, cbcr_full_tex, theme_main_chain.input_frames, pts_int, duration);
+               cards[output_card_index].output->send_frame(y_tex, cbcr_full_tex, ycbcr_output_coefficients, theme_main_chain.input_frames, pts_int, duration);
        }
        resource_pool->release_2d_texture(cbcr_full_tex);
 
-       // Set the right state for rgba_tex.
+       // Set the right state for the Y' and CbCr copies.
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
-       glBindTexture(GL_TEXTURE_2D, rgba_tex);
+       glBindTexture(GL_TEXTURE_2D, y_copy_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 = lrint(global_flags.audio_queue_length_ms * 0.001 * TIMEBASE);  // Corresponds to the delay in ResamplingQueue.
-       RefCountedGLsync fence = video_encoder->end_frame(pts_int + av_delay, duration, theme_main_chain.input_frames);
+       glBindTexture(GL_TEXTURE_2D, cbcr_copy_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 = video_encoder->end_frame();
 
-       // The live frame just shows the RGBA texture we just rendered.
-       // It owns rgba_tex now.
+       // The live frame pieces the Y'CbCr texture copies back into RGB and displays them.
+       // It owns y_copy_tex and cbcr_copy_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.setup_chain = [this, y_copy_tex, cbcr_copy_tex]{
+               display_input->set_texture_num(0, y_copy_tex);
+               display_input->set_texture_num(1, cbcr_copy_tex);
        };
        live_frame.ready_fence = fence;
        live_frame.input_frames = {};
-       live_frame.temp_textures = { rgba_tex };
+       live_frame.temp_textures = { y_copy_tex, cbcr_copy_tex };
        output_channel[OUTPUT_LIVE].output_frame(live_frame);
 
        // Set up preview and any additional channels.
@@ -961,7 +1122,7 @@ void Mixer::audio_thread_func()
                ResamplingQueue::RateAdjustmentPolicy rate_adjustment_policy =
                        task.adjust_rate ? ResamplingQueue::ADJUST_RATE : ResamplingQueue::DO_NOT_ADJUST_RATE;
                vector<float> samples_out = audio_mixer.get_output(
-                       double(task.pts_int) / TIMEBASE,
+                       task.frame_timestamp,
                        task.num_samples,
                        rate_adjustment_policy);
 
@@ -1028,6 +1189,13 @@ void Mixer::start_mode_scanning(unsigned card_index)
        last_mode_scan_change[card_index] = steady_clock::now();
 }
 
+map<uint32_t, bmusb::VideoMode> Mixer::get_available_output_video_modes() const
+{
+       assert(desired_output_card_index != -1);
+       unique_lock<mutex> lock(card_mutex);
+       return cards[desired_output_card_index].output->get_available_video_modes();
+}
+
 Mixer::OutputChannel::~OutputChannel()
 {
        if (has_current_frame) {