]> git.sesse.net Git - nageru/blobdiff - mixer.cpp
Send the audio format explicitly down, not just the ID.
[nageru] / mixer.cpp
index b6824d51ef3911034ac700d1a4a2295e3d57fa1b..e8c9a758ad4f6c25bd6fb144cc565c1234ff7999 100644 (file)
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -4,11 +4,11 @@
 
 #include <assert.h>
 #include <epoxy/egl.h>
-#include <init.h>
 #include <movit/effect_chain.h>
 #include <movit/effect_util.h>
 #include <movit/flat_input.h>
 #include <movit/image_format.h>
+#include <movit/init.h>
 #include <movit/resource_pool.h>
 #include <movit/util.h>
 #include <stdint.h>
 #include <thread>
 #include <utility>
 #include <vector>
+#include <arpa/inet.h>
 
 #include "bmusb/bmusb.h"
 #include "context.h"
+#include "decklink_capture.h"
 #include "defs.h"
+#include "flags.h"
 #include "h264encode.h"
 #include "pbo_frame_allocator.h"
 #include "ref_counted_gl_sync.h"
@@ -74,18 +77,36 @@ void insert_new_frame(RefCountedFrame frame, unsigned field_num, bool interlaced
        }
 }
 
+string generate_local_dump_filename(int frame)
+{
+       time_t now = time(NULL);
+       tm now_tm;
+       localtime_r(&now, &now_tm);
+
+       char timestamp[256];
+       strftime(timestamp, sizeof(timestamp), "%F-%T%z", &now_tm);
+
+       // Use the frame number to disambiguate between two cuts starting
+       // on the same second.
+       char filename[256];
+       snprintf(filename, sizeof(filename), "%s%s-f%02d%s",
+               LOCAL_DUMP_PREFIX, timestamp, frame % 100, LOCAL_DUMP_SUFFIX);
+       return filename;
+}
 
 }  // namespace
 
 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)
 {
+       httpd.open_output_file(generate_local_dump_filename(/*frame=*/0).c_str());
        httpd.start(9095);
 
        CHECK(init_movit(MOVIT_SHADER_DIR, MOVIT_DEBUG_OFF));
@@ -114,52 +135,83 @@ 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));
 
-       for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
-               printf("Configuring card %d...\n", card_index);
-               CaptureCard *card = &cards[card_index];
-               card->usb = new BMUSBCapture(card_index);
-               card->usb->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
-               card->frame_allocator.reset(new PBOFrameAllocator(8 << 20, WIDTH, HEIGHT));  // 8 MB.
-               card->usb->set_video_frame_allocator(card->frame_allocator.get());
-               card->surface = create_surface(format);
-               card->usb->set_dequeue_thread_callbacks(
-                       [card]{
-                               eglBindAPI(EGL_OPENGL_API);
-                               card->context = create_context(card->surface);
-                               if (!make_current(card->context, card->surface)) {
-                                       printf("failed to create bmusb context\n");
-                                       exit(1);
-                               }
-                       },
-                       [this]{
-                               resource_pool->clean_context();
-                       });
-               card->resampling_queue.reset(new ResamplingQueue(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY, 2));
-               card->usb->configure_card();
-       }
-
-       BMUSBCapture::start_bm_thread();
+       // 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].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();
@@ -168,7 +220,7 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
 
        // 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));
 }
@@ -176,6 +228,7 @@ 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) {
@@ -184,12 +237,39 @@ Mixer::~Mixer()
                        cards[card_index].should_quit = true;  // Unblock thread.
                        cards[card_index].new_data_ready_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)
@@ -206,7 +286,7 @@ 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;
 }
@@ -229,23 +309,18 @@ void deinterleave_samples(const vector<float> &in, vector<float> *out_l, vector<
 }  // namespace
 
 void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
-                     FrameAllocator::Frame video_frame, size_t video_offset, uint16_t video_format,
-                    FrameAllocator::Frame audio_frame, size_t audio_offset, uint16_t audio_format)
+                     FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
+                    FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)
 {
        CaptureCard *card = &cards[card_index];
 
-       unsigned width, height, second_field_start, frame_rate_nom, frame_rate_den, extra_lines_top, extra_lines_bottom;
-       bool interlaced;
-
-       decode_video_format(video_format, &width, &height, &second_field_start, &extra_lines_top, &extra_lines_bottom,
-                           &frame_rate_nom, &frame_rate_den, &interlaced);  // Ignore return value for now.
-       int64_t frame_length = TIMEBASE * frame_rate_den / frame_rate_nom;
+       int64_t frame_length = int64_t(TIMEBASE * video_format.frame_rate_den) / video_format.frame_rate_nom;
 
        size_t num_samples = (audio_frame.len >= audio_offset) ? (audio_frame.len - audio_offset) / 8 / 3 : 0;
        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);
                }
@@ -264,7 +339,14 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        // Convert the audio to stereo fp32 and add it.
        vector<float> audio;
        audio.resize(num_samples * 2);
-       convert_fixed24_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, 8, num_samples);
+       switch (audio_format.bits_per_sample) {
+       case 24:
+               convert_fixed24_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.
        {
@@ -272,7 +354,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
                // Number of samples per frame if we need to insert silence.
                // (Could be nonintegral, but resampling will save us then.)
-               int silence_samples = OUTPUT_FREQUENCY * frame_rate_den / frame_rate_nom;
+               int silence_samples = OUTPUT_FREQUENCY * video_format.frame_rate_den / video_format.frame_rate_nom;
 
                if (dropped_frames > MAX_FPS * 2) {
                        fprintf(stderr, "Card %d lost more than two seconds (or time code jumping around; from 0x%04x to 0x%04x), resetting resampler\n",
@@ -314,11 +396,12 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                if (card->should_quit) return;
        }
 
+       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 != size_t(width * (height + extra_lines_top + extra_lines_bottom) * 2)) {
+           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);
@@ -341,67 +424,70 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
        PBOFrameAllocator::Userdata *userdata = (PBOFrameAllocator::Userdata *)video_frame.userdata;
 
-       unsigned num_fields = interlaced ? 2 : 1;
+       unsigned num_fields = video_format.interlaced ? 2 : 1;
        timespec frame_upload_start;
-       if (interlaced) {
-               // NOTE: This isn't deinterlacing. This is just sending the two fields along
-               // as separate frames without considering anything like the half-field offset.
-               // We'll need to add a proper deinterlacer on the receiving side to get this right.
-               assert(height % 2 == 0);
-               height /= 2;
+       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 new_frame(video_frame);
 
        // Upload the textures.
-       size_t cbcr_width = width / 2;
+       size_t cbcr_width = video_format.width / 2;
        size_t cbcr_offset = video_offset / 2;
        size_t y_offset = video_frame.size / 2 + video_offset / 2;
 
        for (unsigned field = 0; field < num_fields; ++field) {
-               unsigned field_start_line = (field == 1) ? second_field_start : extra_lines_top + field * (height + 22);
+               unsigned field_start_line = (field == 1) ? video_format.second_field_start : video_format.extra_lines_top + field * (video_format.height + 22);
 
                if (userdata->tex_y[field] == 0 ||
                    userdata->tex_cbcr[field] == 0 ||
-                   width != userdata->last_width[field] ||
-                   height != userdata->last_height[field]) {
+                   video_format.width != userdata->last_width[field] ||
+                   video_format.height != userdata->last_height[field]) {
                        // We changed resolution since last use of this texture, so we need to create
                        // a new object. Note that this each card has its own PBOFrameAllocator,
                        // we don't need to worry about these flip-flopping between resolutions.
                        glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
                        check_error();
-                       glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, cbcr_width, height, 0, GL_RG, GL_UNSIGNED_BYTE, nullptr);
+                       glTexImage2D(GL_TEXTURE_2D, 0, GL_RG8, cbcr_width, video_format.height, 0, GL_RG, GL_UNSIGNED_BYTE, nullptr);
                        check_error();
                        glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
                        check_error();
-                       glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
+                       glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, video_format.width, video_format.height, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
                        check_error();
-                       userdata->last_width[field] = width;
-                       userdata->last_height[field] = height;
+                       userdata->last_width[field] = video_format.width;
+                       userdata->last_height[field] = video_format.height;
                }
 
                GLuint pbo = userdata->pbo;
                check_error();
                glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo);
                check_error();
-               glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, video_frame.size);
+               glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
                check_error();
-               //glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
-               //check_error();
 
                glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr[field]);
                check_error();
-               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, cbcr_width, height, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(cbcr_offset + cbcr_width * field_start_line * sizeof(uint16_t)));
+               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, cbcr_width, video_format.height, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(cbcr_offset + cbcr_width * field_start_line * sizeof(uint16_t)));
                check_error();
                glBindTexture(GL_TEXTURE_2D, userdata->tex_y[field]);
                check_error();
-               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(y_offset + width * field_start_line));
+               glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, video_format.width, video_format.height, GL_RED, GL_UNSIGNED_BYTE, BUFFER_OFFSET(y_offset + video_format.width * field_start_line));
                check_error();
                glBindTexture(GL_TEXTURE_2D, 0);
                check_error();
+               glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
+               check_error();
                GLsync fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
                check_error();
                assert(fence != nullptr);
@@ -431,7 +517,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                        card->new_frame = new_frame;
                        card->new_frame_length = frame_length;
                        card->new_frame_field = field;
-                       card->new_frame_interlaced = interlaced;
+                       card->new_frame_interlaced = video_format.interlaced;
                        card->new_data_ready_fence = fence;
                        card->dropped_frames = dropped_frames;
                        card->new_data_ready_changed.notify_all();
@@ -473,7 +559,6 @@ void Mixer::thread_func()
 
                        for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
                                CaptureCard *card = &cards[card_index];
-                               card_copy[card_index].usb = card->usb;
                                card_copy[card_index].new_data_ready = card->new_data_ready;
                                card_copy[card_index].new_frame = card->new_frame;
                                card_copy[card_index].new_frame_length = card->new_frame_length;
@@ -492,6 +577,7 @@ void Mixer::thread_func()
                }
 
                // Resample the audio as needed, including from previously dropped frames.
+               assert(num_cards > 0);
                for (unsigned frame_num = 0; frame_num < card_copy[0].dropped_frames + 1; ++frame_num) {
                        {
                                // Signal to the audio thread to process this frame.
@@ -509,7 +595,7 @@ void Mixer::thread_func()
                }
 
                if (audio_level_callback != nullptr) {
-                       unique_lock<mutex> lock(r128_mutex);
+                       unique_lock<mutex> lock(compressor_mutex);
                        double loudness_s = r128.loudness_S();
                        double loudness_i = r128.integrated();
                        double loudness_range_low = r128.range_min();
@@ -517,7 +603,8 @@ void Mixer::thread_func()
 
                        audio_level_callback(loudness_s, 20.0 * log10(peak),
                                             loudness_i, loudness_range_low, loudness_range_high,
-                                            last_gain_staging_db);
+                                            gain_staging_db, 20.0 * log10(final_makeup_gain),
+                                            correlation.get_correlation());
                }
 
                for (unsigned card_index = 1; card_index < num_cards; ++card_index) {
@@ -561,6 +648,7 @@ void Mixer::thread_func()
                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);
@@ -626,6 +714,15 @@ void Mixer::thread_func()
                //      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->shutdown();
+                       httpd.close_output_file();
+                       httpd.open_output_file(filename.c_str());
+                       h264_encoder.reset(new H264Encoder(h264_encoder_surface, global_flags.va_display, WIDTH, HEIGHT, &httpd));
+               }
+
 #if 0
                // Reset every 100 frames, so that local variations in frame times
                // (especially for the first few frames, when the shaders are
@@ -662,6 +759,11 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
 {
        vector<float> samples_card;
        vector<float> samples_out;
+
+       // TODO: Allow mixing audio from several sources.
+       unsigned selected_audio_card = theme->map_signal(audio_source_channel);
+       assert(selected_audio_card < num_cards);
+
        for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
                samples_card.resize(num_samples * 2);
                {
@@ -670,8 +772,7 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
                                printf("Card %d reported previous underrun.\n", card_index);
                        }
                }
-               // TODO: Allow using audio from the other card(s) as well.
-               if (card_index == 0) {
+               if (card_index == selected_audio_card) {
                        samples_out = move(samples_card);
                }
        }
@@ -680,7 +781,9 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
        // we don't need it for voice, and it will reduce headroom
        // and confuse the compressor. (In particular, any hums at 50 or 60 Hz
        // should be dampened.)
-       locut.render(samples_out.data(), samples_out.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
+       if (locut_enabled) {
+               locut.render(samples_out.data(), samples_out.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
+       }
 
        // Apply a level compressor to get the general level right.
        // Basically, if it's over about -40 dBFS, we squeeze it down to that level
@@ -688,15 +791,23 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
        // then apply a makeup gain to get it to -14 dBFS. -14 dBFS is, of course,
        // entirely arbitrary, but from practical tests with speech, it seems to
        // put ut around -23 LUFS, so it's a reasonable starting point for later use.
-       float ref_level_dbfs = -14.0f;
        {
-               float threshold = 0.01f;   // -40 dBFS.
-               float ratio = 20.0f;
-               float attack_time = 0.5f;
-               float release_time = 20.0f;
-               float makeup_gain = pow(10.0f, (ref_level_dbfs - (-40.0f)) / 20.0f);  // +26 dB.
-               level_compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
-               last_gain_staging_db = 20.0 * log10(level_compressor.get_attenuation() * makeup_gain);
+               unique_lock<mutex> lock(compressor_mutex);
+               if (level_compressor_enabled) {
+                       float threshold = 0.01f;   // -40 dBFS.
+                       float ratio = 20.0f;
+                       float attack_time = 0.5f;
+                       float release_time = 20.0f;
+                       float makeup_gain = pow(10.0f, (ref_level_dbfs - (-40.0f)) / 20.0f);  // +26 dB.
+                       level_compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
+                       gain_staging_db = 20.0 * log10(level_compressor.get_attenuation() * makeup_gain);
+               } else {
+                       // Just apply the gain we already had.
+                       float g = pow(10.0f, gain_staging_db / 20.0f);
+                       for (size_t i = 0; i < samples_out.size(); ++i) {
+                               samples_out[i] *= g;
+                       }
+               }
        }
 
 #if 0
@@ -745,15 +856,57 @@ void Mixer::process_audio_one_frame(int64_t frame_pts_int, int num_samples)
                peak_resampler.process();
                size_t out_stereo_samples = interpolated_samples_out.size() / 2 - peak_resampler.out_count;
                peak = max<float>(peak, find_peak(interpolated_samples_out.data(), out_stereo_samples * 2));
+               peak_resampler.out_data = nullptr;
+       }
+
+       // At this point, we are most likely close to +0 LU, but all of our
+       // measurements have been on raw sample values, not R128 values.
+       // So we have a final makeup gain to get us to +0 LU; the gain
+       // adjustments required should be relatively small, and also, the
+       // offset shouldn't change much (only if the type of audio changes
+       // significantly). Thus, we shoot for updating this value basically
+       // “whenever we process buffers”, since the R128 calculation isn't exactly
+       // something we get out per-sample.
+       //
+       // Note that there's a feedback loop here, so we choose a very slow filter
+       // (half-time of 100 seconds).
+       double target_loudness_factor, alpha;
+       {
+               unique_lock<mutex> lock(compressor_mutex);
+               double loudness_lu = r128.loudness_M() - ref_level_lufs;
+               double current_makeup_lu = 20.0f * log10(final_makeup_gain);
+               target_loudness_factor = pow(10.0f, -loudness_lu / 20.0f);
+
+               // If we're outside +/- 5 LU uncorrected, we don't count it as
+               // a normal signal (probably silence) and don't change the
+               // correction factor; just apply what we already have.
+               if (fabs(loudness_lu - current_makeup_lu) >= 5.0 || !final_makeup_gain_auto) {
+                       alpha = 0.0;
+               } else {
+                       // Formula adapted from
+                       // https://en.wikipedia.org/wiki/Low-pass_filter#Simple_infinite_impulse_response_filter.
+                       const double half_time_s = 100.0;
+                       const double fc_mul_2pi_delta_t = 1.0 / (half_time_s * OUTPUT_FREQUENCY);
+                       alpha = fc_mul_2pi_delta_t / (fc_mul_2pi_delta_t + 1.0);
+               }
+
+               double m = final_makeup_gain;
+               for (size_t i = 0; i < samples_out.size(); i += 2) {
+                       samples_out[i + 0] *= m;
+                       samples_out[i + 1] *= m;
+                       m += (target_loudness_factor - m) * alpha;
+               }
+               final_makeup_gain = m;
        }
 
-       // Find R128 levels.
+       // Find R128 levels and L/R correlation.
        vector<float> left, right;
        deinterleave_samples(samples_out, &left, &right);
        float *ptrs[] = { left.data(), right.data() };
        {
-               unique_lock<mutex> lock(r128_mutex);
+               unique_lock<mutex> lock(compressor_mutex);
                r128.process(left.size(), ptrs);
+               correlation.process_samples(samples_out);
        }
 
        // Send the samples to the sound card.
@@ -771,12 +924,6 @@ void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
        glGenVertexArrays(1, &vao);
        check_error();
 
-       float vertices[] = {
-               0.0f, 2.0f,
-               0.0f, 0.0f,
-               2.0f, 0.0f
-       };
-
        glBindVertexArray(vao);
        check_error();
 
@@ -803,17 +950,28 @@ void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
        float chroma_offset_0[] = { -0.5f / WIDTH, 0.0f };
        set_uniform_vec2(cbcr_program_num, "foo", "chroma_offset_0", chroma_offset_0);
 
-       GLuint position_vbo = fill_vertex_attribute(cbcr_program_num, "position", 2, GL_FLOAT, sizeof(vertices), vertices);
-       GLuint texcoord_vbo = fill_vertex_attribute(cbcr_program_num, "texcoord", 2, GL_FLOAT, sizeof(vertices), vertices);  // Same as vertices.
+       glBindBuffer(GL_ARRAY_BUFFER, cbcr_vbo);
+       check_error();
+
+       for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
+               glEnableVertexAttribArray(attr_index);
+               check_error();
+               glVertexAttribPointer(attr_index, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
+               check_error();
+       }
 
        glDrawArrays(GL_TRIANGLES, 0, 3);
        check_error();
 
-       cleanup_vertex_attribute(cbcr_program_num, "position", position_vbo);
-       cleanup_vertex_attribute(cbcr_program_num, "texcoord", texcoord_vbo);
+       for (GLint attr_index : { cbcr_position_attribute_index, cbcr_texcoord_attribute_index }) {
+               glDisableVertexAttribArray(attr_index);
+               check_error();
+       }
 
        glUseProgram(0);
        check_error();
+       glBindFramebuffer(GL_FRAMEBUFFER, 0);
+       check_error();
 
        resource_pool->release_fbo(fbo);
        glDeleteVertexArrays(1, &vao);
@@ -858,6 +1016,7 @@ void Mixer::reset_meters()
        peak = 0.0f;
        r128.reset();
        r128.integr_start();
+       correlation.reset();
 }
 
 Mixer::OutputChannel::~OutputChannel()