]> git.sesse.net Git - nageru/blob - mixer.cpp
Clean up the theme.lua signal numbers a bit by making them symbolic.
[nageru] / mixer.cpp
1 #define WIDTH 1280
2 #define HEIGHT 720
3 #define EXTRAHEIGHT 30
4
5 #undef Success
6
7 #include "mixer.h"
8
9 #include <assert.h>
10 #include <epoxy/egl.h>
11 #include <init.h>
12 #include <movit/effect_chain.h>
13 #include <movit/effect_util.h>
14 #include <movit/flat_input.h>
15 #include <movit/image_format.h>
16 #include <movit/resource_pool.h>
17 #include <stdint.h>
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <sys/time.h>
21 #include <time.h>
22 #include <util.h>
23 #include <algorithm>
24 #include <cmath>
25 #include <condition_variable>
26 #include <cstddef>
27 #include <memory>
28 #include <mutex>
29 #include <string>
30 #include <thread>
31 #include <utility>
32 #include <vector>
33
34 #include "bmusb/bmusb.h"
35 #include "context.h"
36 #include "h264encode.h"
37 #include "pbo_frame_allocator.h"
38 #include "ref_counted_gl_sync.h"
39 #include "timebase.h"
40
41 class QOpenGLContext;
42
43 using namespace movit;
44 using namespace std;
45 using namespace std::placeholders;
46
47 Mixer *global_mixer = nullptr;
48
49 namespace {
50
51 void convert_fixed24_to_fp32(float *dst, size_t out_channels, const uint8_t *src, size_t in_channels, size_t num_samples)
52 {
53         for (size_t i = 0; i < num_samples; ++i) {
54                 for (size_t j = 0; j < out_channels; ++j) {
55                         uint32_t s1 = *src++;
56                         uint32_t s2 = *src++;
57                         uint32_t s3 = *src++;
58                         uint32_t s = s1 | (s1 << 8) | (s2 << 16) | (s3 << 24);
59                         dst[i * out_channels + j] = int(s) * (1.0f / 4294967296.0f);
60                 }
61                 src += 3 * (in_channels - out_channels);
62         }
63 }
64
65 }  // namespace
66
67 Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
68         : httpd("test.ts", WIDTH, HEIGHT),
69           num_cards(num_cards),
70           mixer_surface(create_surface(format)),
71           h264_encoder_surface(create_surface(format))
72 {
73         httpd.start(9095);
74
75         CHECK(init_movit(MOVIT_SHADER_DIR, MOVIT_DEBUG_OFF));
76         check_error();
77
78         // Since we allow non-bouncing 4:2:2 YCbCrInputs, effective subpixel precision
79         // will be halved when sampling them, and we need to compensate here.
80         movit_texel_subpixel_precision /= 2.0;
81
82         resource_pool.reset(new ResourcePool);
83         theme.reset(new Theme("theme.lua", resource_pool.get(), num_cards));
84         for (unsigned i = 0; i < NUM_OUTPUTS; ++i) {
85                 output_channel[i].parent = this;
86         }
87
88         ImageFormat inout_format;
89         inout_format.color_space = COLORSPACE_sRGB;
90         inout_format.gamma_curve = GAMMA_sRGB;
91
92         // Display chain; shows the live output produced by the main chain (its RGBA version).
93         display_chain.reset(new EffectChain(WIDTH, HEIGHT, resource_pool.get()));
94         check_error();
95         display_input = new FlatInput(inout_format, FORMAT_RGB, GL_UNSIGNED_BYTE, WIDTH, HEIGHT);  // FIXME: GL_UNSIGNED_BYTE is really wrong.
96         display_chain->add_input(display_input);
97         display_chain->add_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED);
98         display_chain->set_dither_bits(0);  // Don't bother.
99         display_chain->finalize();
100
101         h264_encoder.reset(new H264Encoder(h264_encoder_surface, WIDTH, HEIGHT, &httpd));
102
103         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
104                 printf("Configuring card %d...\n", card_index);
105                 CaptureCard *card = &cards[card_index];
106                 card->usb = new BMUSBCapture(card_index);
107                 card->usb->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
108                 card->frame_allocator.reset(new PBOFrameAllocator(WIDTH * (HEIGHT+EXTRAHEIGHT) * 2 + 44, WIDTH, HEIGHT));
109                 card->usb->set_video_frame_allocator(card->frame_allocator.get());
110                 card->surface = create_surface(format);
111                 card->usb->set_dequeue_thread_callbacks(
112                         [card]{
113                                 eglBindAPI(EGL_OPENGL_API);
114                                 card->context = create_context();
115                                 if (!make_current(card->context, card->surface)) {
116                                         printf("failed to create bmusb context\n");
117                                         exit(1);
118                                 }
119                         },
120                         [this]{
121                                 resource_pool->clean_context();
122                         });
123                 card->resampler.reset(new Resampler(48000.0, 48000.0, 2));
124                 card->usb->configure_card();
125         }
126
127         BMUSBCapture::start_bm_thread();
128
129         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
130                 cards[card_index].usb->start_bm_capture();
131         }
132
133         //chain->enable_phase_timing(true);
134
135         // Set up stuff for NV12 conversion.
136
137         // Cb/Cr shader.
138         string cbcr_vert_shader = read_file("vs-cbcr.130.vert");
139         string cbcr_frag_shader =
140                 "#version 130 \n"
141                 "in vec2 tc0; \n"
142                 "uniform sampler2D cbcr_tex; \n"
143                 "void main() { \n"
144                 "    gl_FragColor = texture2D(cbcr_tex, tc0); \n"
145                 "} \n";
146         cbcr_program_num = resource_pool->compile_glsl_program(cbcr_vert_shader, cbcr_frag_shader);
147
148         r128.init(2, 48000);
149         r128.integr_start();
150 }
151
152 Mixer::~Mixer()
153 {
154         resource_pool->release_glsl_program(cbcr_program_num);
155         BMUSBCapture::stop_bm_thread();
156
157         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
158                 {
159                         unique_lock<mutex> lock(bmusb_mutex);
160                         cards[card_index].should_quit = true;  // Unblock thread.
161                         cards[card_index].new_data_ready_changed.notify_all();
162                 }
163                 cards[card_index].usb->stop_dequeue_thread();
164         }
165 }
166
167 namespace {
168
169 int unwrap_timecode(uint16_t current_wrapped, int last)
170 {
171         uint16_t last_wrapped = last & 0xffff;
172         if (current_wrapped > last_wrapped) {
173                 return (last & ~0xffff) | current_wrapped;
174         } else {
175                 return 0x10000 + ((last & ~0xffff) | current_wrapped);
176         }
177 }
178
179 float find_peak(const vector<float> &samples)
180 {
181         float m = fabs(samples[0]);
182         for (size_t i = 1; i < samples.size(); ++i) {
183                 m = std::max(m, fabs(samples[i]));
184         }
185         return m;
186 }
187
188 void deinterleave_samples(const vector<float> &in, vector<float> *out_l, vector<float> *out_r)
189 {
190         size_t num_samples = in.size() / 2;
191         out_l->resize(num_samples);
192         out_r->resize(num_samples);
193
194         const float *inptr = in.data();
195         float *lptr = &(*out_l)[0];
196         float *rptr = &(*out_r)[0];
197         for (size_t i = 0; i < num_samples; ++i) {
198                 *lptr++ = *inptr++;
199                 *rptr++ = *inptr++;
200         }
201 }
202
203 }  // namespace
204
205 void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
206                      FrameAllocator::Frame video_frame, size_t video_offset, uint16_t video_format,
207                      FrameAllocator::Frame audio_frame, size_t audio_offset, uint16_t audio_format)
208 {
209         CaptureCard *card = &cards[card_index];
210
211         if (audio_frame.len - audio_offset > 30000) {
212                 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",
213                         card_index, int(audio_frame.len), int(audio_offset),
214                         timecode, int(video_frame.len), int(video_offset), video_format);
215                 if (video_frame.owner) {
216                         video_frame.owner->release_frame(video_frame);
217                 }
218                 if (audio_frame.owner) {
219                         audio_frame.owner->release_frame(audio_frame);
220                 }
221                 return;
222         }
223
224         int unwrapped_timecode = timecode;
225         int dropped_frames = 0;
226         if (card->last_timecode != -1) {
227                 unwrapped_timecode = unwrap_timecode(unwrapped_timecode, card->last_timecode);
228                 dropped_frames = unwrapped_timecode - card->last_timecode - 1;
229         }
230         card->last_timecode = unwrapped_timecode;
231
232         // Convert the audio to stereo fp32 and add it.
233         size_t num_samples = (audio_frame.len >= audio_offset) ? (audio_frame.len - audio_offset) / 8 / 3 : 0;
234         vector<float> audio;
235         audio.resize(num_samples * 2);
236         convert_fixed24_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, 8, num_samples);
237
238         // Add the audio.
239         {
240                 unique_lock<mutex> lock(card->audio_mutex);
241
242                 int unwrapped_timecode = timecode;
243                 if (dropped_frames > 60 * 2) {
244                         fprintf(stderr, "Card %d lost more than two seconds (or time code jumping around), resetting resampler\n",
245                                 card_index);
246                         card->resampler.reset(new Resampler(48000.0, 48000.0, 2));
247                 } else if (dropped_frames > 0) {
248                         // Insert silence as needed.
249                         fprintf(stderr, "Card %d dropped %d frame(s) (before timecode 0x%04x), inserting silence.\n",
250                                 card_index, dropped_frames, timecode);
251                         vector<float> silence;
252                         silence.resize((48000 / 60) * 2);
253                         for (int i = 0; i < dropped_frames; ++i) {
254                                 card->resampler->add_input_samples((unwrapped_timecode - dropped_frames + i) / 60.0, silence.data(), (48000 / 60));
255                         }
256                 }
257                 card->resampler->add_input_samples(unwrapped_timecode / 60.0, audio.data(), num_samples);
258         }
259
260         // Done with the audio, so release it.
261         if (audio_frame.owner) {
262                 audio_frame.owner->release_frame(audio_frame);
263         }
264
265         {
266                 // Wait until the previous frame was consumed.
267                 unique_lock<mutex> lock(bmusb_mutex);
268                 card->new_data_ready_changed.wait(lock, [card]{ return !card->new_data_ready || card->should_quit; });
269                 if (card->should_quit) return;
270         }
271
272         if (video_frame.len - video_offset != WIDTH * (HEIGHT+EXTRAHEIGHT) * 2) {
273                 if (video_frame.len != 0) {
274                         printf("Card %d: Dropping video frame with wrong length (%ld)\n",
275                                 card_index, video_frame.len - video_offset);
276                 }
277                 if (video_frame.owner) {
278                         video_frame.owner->release_frame(video_frame);
279                 }
280
281                 // Still send on the information that we _had_ a frame, even though it's corrupted,
282                 // so that pts can go up accordingly.
283                 {
284                         unique_lock<mutex> lock(bmusb_mutex);
285                         card->new_data_ready = true;
286                         card->new_frame = RefCountedFrame(FrameAllocator::Frame());
287                         card->new_data_ready_fence = nullptr;
288                         card->dropped_frames = dropped_frames;
289                         card->new_data_ready_changed.notify_all();
290                 }
291                 return;
292         }
293
294         const PBOFrameAllocator::Userdata *userdata = (const PBOFrameAllocator::Userdata *)video_frame.userdata;
295         GLuint pbo = userdata->pbo;
296         check_error();
297         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbo);
298         check_error();
299         glFlushMappedBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, video_frame.size);
300         check_error();
301         //glMemoryBarrier(GL_CLIENT_MAPPED_BUFFER_BARRIER_BIT);
302         //check_error();
303
304         // Upload the textures.
305         glBindTexture(GL_TEXTURE_2D, userdata->tex_y);
306         check_error();
307         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));
308         check_error();
309         glBindTexture(GL_TEXTURE_2D, userdata->tex_cbcr);
310         check_error();
311         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, WIDTH/2, HEIGHT, GL_RG, GL_UNSIGNED_BYTE, BUFFER_OFFSET(WIDTH * 25 + 22));
312         check_error();
313         glBindTexture(GL_TEXTURE_2D, 0);
314         check_error();
315         GLsync fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);              
316         check_error();
317         assert(fence != nullptr);
318
319         {
320                 unique_lock<mutex> lock(bmusb_mutex);
321                 card->new_data_ready = true;
322                 card->new_frame = RefCountedFrame(video_frame);
323                 card->new_data_ready_fence = fence;
324                 card->dropped_frames = dropped_frames;
325                 card->new_data_ready_changed.notify_all();
326         }
327 }
328
329 void Mixer::thread_func()
330 {
331         eglBindAPI(EGL_OPENGL_API);
332         QOpenGLContext *context = create_context();
333         if (!make_current(context, mixer_surface)) {
334                 printf("oops\n");
335                 exit(1);
336         }
337
338         struct timespec start, now;
339         clock_gettime(CLOCK_MONOTONIC, &start);
340
341         int frame = 0;
342         int dropped_frames = 0;
343
344         while (!should_quit) {
345                 CaptureCard card_copy[MAX_CARDS];
346
347                 {
348                         unique_lock<mutex> lock(bmusb_mutex);
349
350                         // The first card is the master timer, so wait for it to have a new frame.
351                         // TODO: Make configurable, and with a timeout.
352                         cards[0].new_data_ready_changed.wait(lock, [this]{ return cards[0].new_data_ready; });
353
354                         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
355                                 CaptureCard *card = &cards[card_index];
356                                 card_copy[card_index].usb = card->usb;
357                                 card_copy[card_index].new_data_ready = card->new_data_ready;
358                                 card_copy[card_index].new_frame = card->new_frame;
359                                 card_copy[card_index].new_data_ready_fence = card->new_data_ready_fence;
360                                 card_copy[card_index].new_frame_audio = move(card->new_frame_audio);
361                                 card_copy[card_index].dropped_frames = card->dropped_frames;
362                                 card->new_data_ready = false;
363                                 card->new_data_ready_changed.notify_all();
364                         }
365                 }
366
367                 // Resample the audio as needed, including from previously dropped frames.
368                 vector<float> samples_out;
369                 // TODO: Allow using audio from the other card(s) as well.
370                 for (unsigned frame_num = 0; frame_num < card_copy[0].dropped_frames + 1; ++frame_num) {
371                         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
372                                 samples_out.resize((48000 / 60) * 2);
373                                 {
374                                         unique_lock<mutex> lock(cards[card_index].audio_mutex);
375                                         if (!cards[card_index].resampler->get_output_samples(pts(), &samples_out[0], 48000 / 60)) {
376                                                 printf("Card %d reported previous underrun.\n", card_index);
377                                         }
378                                 }
379                                 if (card_index == 0) {
380                                         vector<float> left, right;
381                                         peak = std::max(peak, find_peak(samples_out));
382                                         deinterleave_samples(samples_out, &left, &right);
383                                         float *ptrs[] = { left.data(), right.data() };
384                                         r128.process(left.size(), ptrs);
385                                         h264_encoder->add_audio(pts_int, move(samples_out));
386                                 }
387                         }
388                         if (frame_num != card_copy[0].dropped_frames) {
389                                 // For dropped frames, increase the pts.
390                                 ++dropped_frames;
391                                 pts_int += TIMEBASE / 60;
392                         }
393                 }
394
395                 if (audio_level_callback != nullptr) {
396                         double loudness_s = r128.loudness_S();
397                         double loudness_i = r128.integrated();
398                         double loudness_range_low = r128.range_min();
399                         double loudness_range_high = r128.range_max();
400
401                         audio_level_callback(loudness_s, 20.0 * log10(peak),
402                                              loudness_i, loudness_range_low, loudness_range_high);
403                 }
404
405                 for (unsigned card_index = 1; card_index < num_cards; ++card_index) {
406                         if (card_copy[card_index].new_data_ready && card_copy[card_index].new_frame->len == 0) {
407                                 ++card_copy[card_index].dropped_frames;
408                         }
409                         if (card_copy[card_index].dropped_frames > 0) {
410                                 printf("Card %u dropped %d frames before this\n",
411                                         card_index, int(card_copy[card_index].dropped_frames));
412                         }
413                 }
414
415                 // If the first card is reporting a corrupted or otherwise dropped frame,
416                 // just increase the pts (skipping over this frame) and don't try to compute anything new.
417                 if (card_copy[0].new_frame->len == 0) {
418                         ++dropped_frames;
419                         pts_int += TIMEBASE / 60;
420                         continue;
421                 }
422
423                 for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
424                         CaptureCard *card = &card_copy[card_index];
425                         if (!card->new_data_ready || card->new_frame->len == 0)
426                                 continue;
427
428                         assert(card->new_frame != nullptr);
429                         bmusb_current_rendering_frame[card_index] = card->new_frame;
430                         check_error();
431
432                         // The new texture might still be uploaded,
433                         // tell the GPU to wait until it's there.
434                         if (card->new_data_ready_fence) {
435                                 glWaitSync(card->new_data_ready_fence, /*flags=*/0, GL_TIMEOUT_IGNORED);
436                                 check_error();
437                                 glDeleteSync(card->new_data_ready_fence);
438                                 check_error();
439                         }
440                         const PBOFrameAllocator::Userdata *userdata = (const PBOFrameAllocator::Userdata *)card->new_frame->userdata;
441                         theme->set_input_textures(card_index, userdata->tex_y, userdata->tex_cbcr);
442                 }
443
444                 // Get the main chain from the theme, and set its state immediately.
445                 pair<EffectChain *, function<void()>> theme_main_chain = theme->get_chain(0, pts(), WIDTH, HEIGHT);
446                 EffectChain *chain = theme_main_chain.first;
447                 theme_main_chain.second();
448
449                 GLuint y_tex, cbcr_tex;
450                 bool got_frame = h264_encoder->begin_frame(&y_tex, &cbcr_tex);
451                 assert(got_frame);
452
453                 // Render main chain.
454                 GLuint cbcr_full_tex = resource_pool->create_2d_texture(GL_RG8, WIDTH, HEIGHT);
455                 GLuint rgba_tex = resource_pool->create_2d_texture(GL_RGB565, WIDTH, HEIGHT);  // Saves texture bandwidth, although dithering gets messed up.
456                 GLuint fbo = resource_pool->create_fbo(y_tex, cbcr_full_tex, rgba_tex);
457                 check_error();
458                 chain->render_to_fbo(fbo, WIDTH, HEIGHT);
459                 resource_pool->release_fbo(fbo);
460
461                 subsample_chroma(cbcr_full_tex, cbcr_tex);
462                 resource_pool->release_2d_texture(cbcr_full_tex);
463
464                 // Set the right state for rgba_tex.
465                 glBindFramebuffer(GL_FRAMEBUFFER, 0);
466                 glBindTexture(GL_TEXTURE_2D, rgba_tex);
467                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
468                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
469                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
470
471                 RefCountedGLsync fence(GL_SYNC_GPU_COMMANDS_COMPLETE, /*flags=*/0);
472                 check_error();
473
474                 // Make sure the H.264 gets a reference to all the
475                 // input frames needed, so that they are not released back
476                 // until the rendering is done.
477                 vector<RefCountedFrame> input_frames;
478                 for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
479                         input_frames.push_back(bmusb_current_rendering_frame[card_index]);
480                 }
481                 const int64_t av_delay = TIMEBASE / 10;  // Corresponds to the fixed delay in resampler.h. TODO: Make less hard-coded.
482                 h264_encoder->end_frame(fence, pts_int + av_delay, input_frames);
483                 ++frame;
484                 pts_int += TIMEBASE / 60;
485
486                 // The live frame just shows the RGBA texture we just rendered.
487                 // It owns rgba_tex now.
488                 DisplayFrame live_frame;
489                 live_frame.chain = display_chain.get();
490                 live_frame.setup_chain = [this, rgba_tex]{
491                         display_input->set_texture_num(rgba_tex);
492                 };
493                 live_frame.ready_fence = fence;
494                 live_frame.input_frames = {};
495                 live_frame.temp_textures = { rgba_tex };
496                 output_channel[OUTPUT_LIVE].output_frame(live_frame);
497
498                 // Set up preview and any additional channels.
499                 for (int i = 1; i < theme->get_num_channels() + 2; ++i) {
500                         DisplayFrame display_frame;
501                         pair<EffectChain *, function<void()>> chain = theme->get_chain(i, pts(), WIDTH, HEIGHT);  // FIXME: dimensions
502                         display_frame.chain = chain.first;
503                         display_frame.setup_chain = chain.second;
504                         display_frame.ready_fence = fence;
505
506                         // FIXME: possible to do better?
507                         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
508                                 display_frame.input_frames.push_back(bmusb_current_rendering_frame[card_index]);
509                         }
510                         display_frame.temp_textures = {};
511                         output_channel[i].output_frame(display_frame);
512                 }
513
514                 clock_gettime(CLOCK_MONOTONIC, &now);
515                 double elapsed = now.tv_sec - start.tv_sec +
516                         1e-9 * (now.tv_nsec - start.tv_nsec);
517                 if (frame % 100 == 0) {
518                         printf("%d frames (%d dropped) in %.3f seconds = %.1f fps (%.1f ms/frame)\n",
519                                 frame, dropped_frames, elapsed, frame / elapsed,
520                                 1e3 * elapsed / frame);
521                 //      chain->print_phase_timing();
522                 }
523
524 #if 0
525                 // Reset every 100 frames, so that local variations in frame times
526                 // (especially for the first few frames, when the shaders are
527                 // compiled etc.) don't make it hard to measure for the entire
528                 // remaining duration of the program.
529                 if (frame == 10000) {
530                         frame = 0;
531                         start = now;
532                 }
533 #endif
534                 check_error();
535         }
536
537         resource_pool->clean_context();
538 }
539
540 void Mixer::subsample_chroma(GLuint src_tex, GLuint dst_tex)
541 {
542         GLuint vao;
543         glGenVertexArrays(1, &vao);
544         check_error();
545
546         float vertices[] = {
547                 0.0f, 2.0f,
548                 0.0f, 0.0f,
549                 2.0f, 0.0f
550         };
551
552         glBindVertexArray(vao);
553         check_error();
554
555         // Extract Cb/Cr.
556         GLuint fbo = resource_pool->create_fbo(dst_tex);
557         glBindFramebuffer(GL_FRAMEBUFFER, fbo);
558         glViewport(0, 0, WIDTH/2, HEIGHT/2);
559         check_error();
560
561         glUseProgram(cbcr_program_num);
562         check_error();
563
564         glActiveTexture(GL_TEXTURE0);
565         check_error();
566         glBindTexture(GL_TEXTURE_2D, src_tex);
567         check_error();
568         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
569         check_error();
570         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
571         check_error();
572         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
573         check_error();
574
575         float chroma_offset_0[] = { -0.5f / WIDTH, 0.0f };
576         set_uniform_vec2(cbcr_program_num, "foo", "chroma_offset_0", chroma_offset_0);
577
578         GLuint position_vbo = fill_vertex_attribute(cbcr_program_num, "position", 2, GL_FLOAT, sizeof(vertices), vertices);
579         GLuint texcoord_vbo = fill_vertex_attribute(cbcr_program_num, "texcoord", 2, GL_FLOAT, sizeof(vertices), vertices);  // Same as vertices.
580
581         glDrawArrays(GL_TRIANGLES, 0, 3);
582         check_error();
583
584         cleanup_vertex_attribute(cbcr_program_num, "position", position_vbo);
585         cleanup_vertex_attribute(cbcr_program_num, "texcoord", texcoord_vbo);
586
587         glUseProgram(0);
588         check_error();
589
590         resource_pool->release_fbo(fbo);
591         glDeleteVertexArrays(1, &vao);
592 }
593
594 void Mixer::release_display_frame(DisplayFrame *frame)
595 {
596         for (GLuint texnum : frame->temp_textures) {
597                 resource_pool->release_2d_texture(texnum);
598         }
599         frame->temp_textures.clear();
600         frame->ready_fence.reset();
601         frame->input_frames.clear();
602 }
603
604 void Mixer::start()
605 {
606         mixer_thread = thread(&Mixer::thread_func, this);
607 }
608
609 void Mixer::quit()
610 {
611         should_quit = true;
612         mixer_thread.join();
613 }
614
615 void Mixer::transition_clicked(int transition_num)
616 {
617         theme->transition_clicked(transition_num, pts());
618 }
619
620 void Mixer::channel_clicked(int preview_num)
621 {
622         theme->channel_clicked(preview_num);
623 }
624
625 Mixer::OutputChannel::~OutputChannel()
626 {
627         if (has_current_frame) {
628                 parent->release_display_frame(&current_frame);
629         }
630         if (has_ready_frame) {
631                 parent->release_display_frame(&ready_frame);
632         }
633 }
634
635 void Mixer::OutputChannel::output_frame(DisplayFrame frame)
636 {
637         // Store this frame for display. Remove the ready frame if any
638         // (it was seemingly never used).
639         {
640                 unique_lock<mutex> lock(frame_mutex);
641                 if (has_ready_frame) {
642                         parent->release_display_frame(&ready_frame);
643                 }
644                 ready_frame = frame;
645                 has_ready_frame = true;
646         }
647
648         if (has_new_frame_ready_callback) {
649                 new_frame_ready_callback();
650         }
651 }
652
653 bool Mixer::OutputChannel::get_display_frame(DisplayFrame *frame)
654 {
655         unique_lock<mutex> lock(frame_mutex);
656         if (!has_current_frame && !has_ready_frame) {
657                 return false;
658         }
659
660         if (has_current_frame && has_ready_frame) {
661                 // We have a new ready frame. Toss the current one.
662                 parent->release_display_frame(&current_frame);
663                 has_current_frame = false;
664         }
665         if (has_ready_frame) {
666                 assert(!has_current_frame);
667                 current_frame = ready_frame;
668                 ready_frame.ready_fence.reset();  // Drop the refcount.
669                 ready_frame.input_frames.clear();  // Drop the refcounts.
670                 has_current_frame = true;
671                 has_ready_frame = false;
672         }
673
674         *frame = current_frame;
675         return true;
676 }
677
678 void Mixer::OutputChannel::set_frame_ready_callback(Mixer::new_frame_ready_callback_t callback)
679 {
680         new_frame_ready_callback = callback;
681         has_new_frame_ready_callback = true;
682 }