4 // The actual video mixer, running in its own separate background thread.
15 #include <condition_variable>
26 #include <movit/image_format.h>
28 #include "audio_mixer.h"
29 #include "bmusb/bmusb.h"
32 #include "input_state.h"
34 #include "pbo_frame_allocator.h"
35 #include "ref_counted_frame.h"
36 #include "ref_counted_gl_sync.h"
39 #include "video_encoder.h"
40 #include "ycbcr_interpretation.h"
43 class ChromaSubsampler;
47 class TimecodeRenderer;
57 // A class to estimate the future jitter. Used in QueueLengthPolicy (see below).
59 // There are many ways to estimate jitter; I've tested a few ones (and also
60 // some algorithms that don't explicitly model jitter) with different
61 // parameters on some real-life data in experiments/queue_drop_policy.cpp.
62 // This is one based on simple order statistics where I've added some margin in
63 // the number of starvation events; I believe that about one every hour would
64 // probably be acceptable, but this one typically goes lower than that, at the
65 // cost of 2–3 ms extra latency. (If the queue is hard-limited to one frame, it's
66 // possible to get ~10 ms further down, but this would mean framedrops every
67 // second or so.) The general strategy is: Take the 99.9-percentile jitter over
68 // last 5000 frames, multiply by two, and that's our worst-case jitter
69 // estimate. The fact that we're not using the max value means that we could
70 // actually even throw away very late frames immediately, which means we only
71 // get one user-visible event instead of seeing something both when the frame
72 // arrives late (duplicate frame) and then again when we drop.
75 static constexpr size_t history_length = 5000;
76 static constexpr double percentile = 0.999;
77 static constexpr double multiplier = 2.0;
80 void register_metrics(const std::vector<std::pair<std::string, std::string>> &labels);
81 void unregister_metrics(const std::vector<std::pair<std::string, std::string>> &labels);
87 void frame_arrived(std::chrono::steady_clock::time_point now, int64_t frame_duration, size_t dropped_frames);
88 std::chrono::steady_clock::time_point get_expected_next_frame() const { return expected_timestamp; }
89 double estimate_max_jitter() const;
92 // A simple O(k) based algorithm for getting the k-th largest or
93 // smallest element from our window; we simply keep the multiset
94 // ordered (insertions and deletions are O(n) as always) and then
95 // iterate from one of the sides. If we had larger values of k,
96 // we could go for a more complicated setup with two sets or heaps
97 // (one increasing and one decreasing) that we keep balanced around
98 // the point, or it is possible to reimplement std::set with
99 // counts in each node. However, since k=5, we don't need this.
100 std::multiset<double> orders;
101 std::deque<std::multiset<double>::iterator> history;
103 std::chrono::steady_clock::time_point expected_timestamp = std::chrono::steady_clock::time_point::min();
105 // Metrics. There are no direct summaries for jitter, since we already have latency summaries.
106 std::atomic<int64_t> metric_input_underestimated_jitter_frames{0};
107 std::atomic<double> metric_input_estimated_max_jitter_seconds{0.0 / 0.0};
110 // For any card that's not the master (where we pick out the frames as they
111 // come, as fast as we can process), there's going to be a queue. The question
112 // is when we should drop frames from that queue (apart from the obvious
113 // dropping if the 16-frame queue should become full), especially given that
114 // the frame rate could be lower or higher than the master (either subtly or
115 // dramatically). We have two (conflicting) demands:
117 // 1. We want to avoid starving the queue.
118 // 2. We don't want to add more delay than is needed.
120 // Our general strategy is to drop as many frames as we can (helping for #2)
121 // that we think is safe for #1 given jitter. To this end, we measure the
122 // deviation from the expected arrival time for all cards, and use that for
123 // continuous jitter estimation.
125 // We then drop everything from the queue that we're sure we won't need to
126 // serve the output in the time before the next frame arrives. Typically,
127 // this means the queue will contain 0 or 1 frames, although more is also
128 // possible if the jitter is very high.
129 class QueueLengthPolicy {
131 QueueLengthPolicy() {}
132 void reset(unsigned card_index) {
133 this->card_index = card_index;
136 void register_metrics(const std::vector<std::pair<std::string, std::string>> &labels);
137 void unregister_metrics(const std::vector<std::pair<std::string, std::string>> &labels);
139 // Call after picking out a frame, so 0 means starvation.
140 void update_policy(std::chrono::steady_clock::time_point now,
141 std::chrono::steady_clock::time_point expected_next_frame,
142 int64_t master_frame_duration,
143 double max_input_card_jitter_seconds,
144 double max_master_card_jitter_seconds);
145 unsigned get_safe_queue_length() const { return safe_queue_length; }
148 unsigned card_index; // For debugging and metrics only.
149 unsigned safe_queue_length = 0; // Can never go below zero.
152 std::atomic<int64_t> metric_input_queue_safe_length_frames{1};
157 // The surface format is used for offscreen destinations for OpenGL contexts we need.
158 Mixer(const QSurfaceFormat &format, unsigned num_cards);
163 void transition_clicked(int transition_num);
164 void channel_clicked(int preview_num);
169 OUTPUT_INPUT0, // 1, 2, 3, up to 15 follow numerically.
173 struct DisplayFrame {
174 // The chain for rendering this frame. To render a display frame,
175 // first wait for <ready_fence>, then call <setup_chain>
176 // to wire up all the inputs, and then finally call
177 // chain->render_to_screen() or similar.
178 movit::EffectChain *chain;
179 std::function<void()> setup_chain;
181 // Asserted when all the inputs are ready; you cannot render the chain
183 RefCountedGLsync ready_fence;
185 // Holds on to all the input frames needed for this display frame,
186 // so they are not released while still rendering.
187 std::vector<RefCountedFrame> input_frames;
189 // Textures that should be released back to the resource pool
190 // when this frame disappears, if any.
191 // TODO: Refcount these as well?
192 std::vector<GLuint> temp_textures;
194 // Implicitly frees the previous one if there's a new frame available.
195 bool get_display_frame(Output output, DisplayFrame *frame) {
196 return output_channel[output].get_display_frame(frame);
199 // NOTE: Callbacks will be called with a mutex held, so you should probably
200 // not do real work in them.
201 typedef std::function<void()> new_frame_ready_callback_t;
202 void add_frame_ready_callback(Output output, void *key, new_frame_ready_callback_t callback)
204 output_channel[output].add_frame_ready_callback(key, callback);
207 void remove_frame_ready_callback(Output output, void *key)
209 output_channel[output].remove_frame_ready_callback(key);
212 // TODO: Should this really be per-channel? Shouldn't it just be called for e.g. the live output?
213 typedef std::function<void(const std::vector<std::string> &)> transition_names_updated_callback_t;
214 void set_transition_names_updated_callback(Output output, transition_names_updated_callback_t callback)
216 output_channel[output].set_transition_names_updated_callback(callback);
219 typedef std::function<void(const std::string &)> name_updated_callback_t;
220 void set_name_updated_callback(Output output, name_updated_callback_t callback)
222 output_channel[output].set_name_updated_callback(callback);
225 typedef std::function<void(const std::string &)> color_updated_callback_t;
226 void set_color_updated_callback(Output output, color_updated_callback_t callback)
228 output_channel[output].set_color_updated_callback(callback);
231 std::vector<std::string> get_transition_names()
233 return theme->get_transition_names(pts());
236 unsigned get_num_channels() const
238 return theme->get_num_channels();
241 std::string get_channel_name(unsigned channel) const
243 return theme->get_channel_name(channel);
246 std::string get_channel_color(unsigned channel) const
248 return theme->get_channel_color(channel);
251 int get_channel_signal(unsigned channel) const
253 return theme->get_channel_signal(channel);
256 int map_signal(unsigned channel)
258 return theme->map_signal(channel);
261 unsigned get_master_clock() const
263 return master_clock_channel;
266 void set_master_clock(unsigned channel)
268 master_clock_channel = channel;
271 void set_signal_mapping(int signal, int card)
273 return theme->set_signal_mapping(signal, card);
276 YCbCrInterpretation get_input_ycbcr_interpretation(unsigned card_index) const;
277 void set_input_ycbcr_interpretation(unsigned card_index, const YCbCrInterpretation &interpretation);
279 bool get_supports_set_wb(unsigned channel) const
281 return theme->get_supports_set_wb(channel);
284 void set_wb(unsigned channel, double r, double g, double b) const
286 theme->set_wb(channel, r, g, b);
289 // Note: You can also get this through the global variable global_audio_mixer.
290 AudioMixer *get_audio_mixer() { return &audio_mixer; }
291 const AudioMixer *get_audio_mixer() const { return &audio_mixer; }
298 unsigned get_num_cards() const { return num_cards; }
300 std::string get_card_description(unsigned card_index) const {
301 assert(card_index < num_cards);
302 return cards[card_index].capture->get_description();
305 // The difference between this and the previous function is that if a card
306 // is used as the current output, get_card_description() will return the
307 // fake card that's replacing it for input, whereas this function will return
308 // the card's actual name.
309 std::string get_output_card_description(unsigned card_index) const {
310 assert(card_can_be_used_as_output(card_index));
311 assert(card_index < num_cards);
312 if (cards[card_index].parked_capture) {
313 return cards[card_index].parked_capture->get_description();
315 return cards[card_index].capture->get_description();
319 bool card_can_be_used_as_output(unsigned card_index) const {
320 assert(card_index < num_cards);
321 return cards[card_index].output != nullptr;
324 std::map<uint32_t, bmusb::VideoMode> get_available_video_modes(unsigned card_index) const {
325 assert(card_index < num_cards);
326 return cards[card_index].capture->get_available_video_modes();
329 uint32_t get_current_video_mode(unsigned card_index) const {
330 assert(card_index < num_cards);
331 return cards[card_index].capture->get_current_video_mode();
334 void set_video_mode(unsigned card_index, uint32_t mode) {
335 assert(card_index < num_cards);
336 cards[card_index].capture->set_video_mode(mode);
339 void start_mode_scanning(unsigned card_index);
341 std::map<uint32_t, std::string> get_available_video_inputs(unsigned card_index) const {
342 assert(card_index < num_cards);
343 return cards[card_index].capture->get_available_video_inputs();
346 uint32_t get_current_video_input(unsigned card_index) const {
347 assert(card_index < num_cards);
348 return cards[card_index].capture->get_current_video_input();
351 void set_video_input(unsigned card_index, uint32_t input) {
352 assert(card_index < num_cards);
353 cards[card_index].capture->set_video_input(input);
356 std::map<uint32_t, std::string> get_available_audio_inputs(unsigned card_index) const {
357 assert(card_index < num_cards);
358 return cards[card_index].capture->get_available_audio_inputs();
361 uint32_t get_current_audio_input(unsigned card_index) const {
362 assert(card_index < num_cards);
363 return cards[card_index].capture->get_current_audio_input();
366 void set_audio_input(unsigned card_index, uint32_t input) {
367 assert(card_index < num_cards);
368 cards[card_index].capture->set_audio_input(input);
371 void change_x264_bitrate(unsigned rate_kbit) {
372 video_encoder->change_x264_bitrate(rate_kbit);
375 int get_output_card_index() const { // -1 = no output, just stream.
376 return desired_output_card_index;
379 void set_output_card(int card_index) { // -1 = no output, just stream.
380 desired_output_card_index = card_index;
383 std::map<uint32_t, bmusb::VideoMode> get_available_output_video_modes() const;
385 uint32_t get_output_video_mode() const {
386 return desired_output_video_mode;
389 void set_output_video_mode(uint32_t mode) {
390 desired_output_video_mode = mode;
393 void set_display_timecode_in_stream(bool enable) {
394 display_timecode_in_stream = enable;
397 void set_display_timecode_on_stdout(bool enable) {
398 display_timecode_on_stdout = enable;
404 enum class CardType {
409 void configure_card(unsigned card_index, bmusb::CaptureInterface *capture, CardType card_type, DeckLinkOutput *output);
410 void set_output_card_internal(int card_index); // Should only be called from the mixer thread.
411 void bm_frame(unsigned card_index, uint16_t timecode,
412 bmusb::FrameAllocator::Frame video_frame, size_t video_offset, bmusb::VideoFormat video_format,
413 bmusb::FrameAllocator::Frame audio_frame, size_t audio_offset, bmusb::AudioFormat audio_format);
414 void bm_hotplug_add(libusb_device *dev);
415 void bm_hotplug_remove(unsigned card_index);
416 void place_rectangle(movit::Effect *resample_effect, movit::Effect *padding_effect, float x0, float y0, float x1, float y1);
418 void handle_hotplugged_cards();
419 void schedule_audio_resampling_tasks(unsigned dropped_frames, int num_samples_per_frame, int length_per_frame, bool is_preroll, std::chrono::steady_clock::time_point frame_timestamp);
420 std::string get_timecode_text() const;
421 void render_one_frame(int64_t duration);
422 void audio_thread_func();
423 void release_display_frame(DisplayFrame *frame);
424 double pts() { return double(pts_int) / TIMEBASE; }
425 void trim_queue(CaptureCard *card, size_t safe_queue_length);
428 unsigned num_cards, num_video_inputs;
430 QSurface *mixer_surface, *h264_encoder_surface, *decklink_output_surface;
431 std::unique_ptr<movit::ResourcePool> resource_pool;
432 std::unique_ptr<Theme> theme;
433 std::atomic<unsigned> audio_source_channel{0};
434 std::atomic<int> master_clock_channel{0}; // Gets overridden by <output_card_index> if set.
435 int output_card_index = -1; // -1 for none.
436 uint32_t output_video_mode = -1;
438 // The mechanics of changing the output card and modes are so intricately connected
439 // with the work the mixer thread is doing. Thus, we don't change it directly,
440 // we just set this variable instead, which signals to the mixer thread that
441 // it should do the change before the next frame. This simplifies locking
442 // considerations immensely.
443 std::atomic<int> desired_output_card_index{-1};
444 std::atomic<uint32_t> desired_output_video_mode{0};
446 std::unique_ptr<movit::EffectChain> display_chain;
447 std::unique_ptr<ChromaSubsampler> chroma_subsampler;
448 std::unique_ptr<v210Converter> v210_converter;
449 std::unique_ptr<VideoEncoder> video_encoder;
451 std::unique_ptr<TimecodeRenderer> timecode_renderer;
452 std::atomic<bool> display_timecode_in_stream{false};
453 std::atomic<bool> display_timecode_on_stdout{false};
455 // Effects part of <display_chain>. Owned by <display_chain>.
456 movit::YCbCrInput *display_input;
458 int64_t pts_int = 0; // In TIMEBASE units.
459 unsigned frame_num = 0;
461 // Accumulated errors in number of 1/TIMEBASE audio samples. If OUTPUT_FREQUENCY divided by
462 // frame rate is integer, will always stay zero.
463 unsigned fractional_samples = 0;
465 mutable std::mutex card_mutex;
466 bool has_bmusb_thread = false;
468 std::unique_ptr<bmusb::CaptureInterface> capture;
469 bool is_fake_capture;
471 std::unique_ptr<DeckLinkOutput> output;
473 // If this card is used for output (ie., output_card_index points to it),
474 // it cannot simultaneously be uesd for capture, so <capture> gets replaced
475 // by a FakeCapture. However, since reconstructing the real capture object
476 // with all its state can be annoying, it is not being deleted, just stopped
478 std::unique_ptr<bmusb::CaptureInterface> parked_capture;
480 std::unique_ptr<PBOFrameAllocator> frame_allocator;
482 // Stuff for the OpenGL context (for texture uploading).
483 QSurface *surface = nullptr;
486 RefCountedFrame frame;
487 int64_t length; // In TIMEBASE units.
489 unsigned field; // Which field (0 or 1) of the frame to use. Always 0 for progressive.
490 std::function<void()> upload_func; // Needs to be called to actually upload the texture to OpenGL.
491 unsigned dropped_frames = 0; // Number of dropped frames before this one.
492 std::chrono::steady_clock::time_point received_timestamp = std::chrono::steady_clock::time_point::min();
494 std::deque<NewFrame> new_frames;
495 bool should_quit = false;
496 std::condition_variable new_frames_changed; // Set whenever new_frames (or should_quit) is changed.
498 QueueLengthPolicy queue_length_policy; // Refers to the "new_frames" queue.
500 int last_timecode = -1; // Unwrapped.
502 JitterHistory jitter_history;
505 std::vector<std::pair<std::string, std::string>> labels;
506 std::atomic<int64_t> metric_input_received_frames{0};
507 std::atomic<int64_t> metric_input_duped_frames{0};
508 std::atomic<int64_t> metric_input_dropped_frames_jitter{0};
509 std::atomic<int64_t> metric_input_dropped_frames_error{0};
510 std::atomic<int64_t> metric_input_resets{0};
511 std::atomic<int64_t> metric_input_queue_length_frames{0};
513 std::atomic<int64_t> metric_input_has_signal_bool{-1};
514 std::atomic<int64_t> metric_input_is_connected_bool{-1};
515 std::atomic<int64_t> metric_input_interlaced_bool{-1};
516 std::atomic<int64_t> metric_input_width_pixels{-1};
517 std::atomic<int64_t> metric_input_height_pixels{-1};
518 std::atomic<int64_t> metric_input_frame_rate_nom{-1};
519 std::atomic<int64_t> metric_input_frame_rate_den{-1};
520 std::atomic<int64_t> metric_input_sample_rate_hz{-1};
522 JitterHistory output_jitter_history;
523 CaptureCard cards[MAX_VIDEO_CARDS]; // Protected by <card_mutex>.
524 YCbCrInterpretation ycbcr_interpretation[MAX_VIDEO_CARDS]; // Protected by <card_mutex>.
525 AudioMixer audio_mixer; // Same as global_audio_mixer (see audio_mixer.h).
526 bool input_card_is_master_clock(unsigned card_index, unsigned master_card_index) const;
527 struct OutputFrameInfo {
528 int dropped_frames; // Since last frame.
529 int num_samples; // Audio samples needed for this output frame.
530 int64_t frame_duration; // In TIMEBASE units.
532 std::chrono::steady_clock::time_point frame_timestamp;
534 OutputFrameInfo 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]);
536 InputState input_state;
538 // Cards we have been noticed about being hotplugged, but haven't tried adding yet.
539 // Protected by its own mutex.
540 std::mutex hotplug_mutex;
541 std::vector<libusb_device *> hotplugged_cards;
543 class OutputChannel {
546 void output_frame(DisplayFrame frame);
547 bool get_display_frame(DisplayFrame *frame);
548 void add_frame_ready_callback(void *key, new_frame_ready_callback_t callback);
549 void remove_frame_ready_callback(void *key);
550 void set_transition_names_updated_callback(transition_names_updated_callback_t callback);
551 void set_name_updated_callback(name_updated_callback_t callback);
552 void set_color_updated_callback(color_updated_callback_t callback);
558 Mixer *parent = nullptr; // Not owned.
559 std::mutex frame_mutex;
560 DisplayFrame current_frame, ready_frame; // protected by <frame_mutex>
561 bool has_current_frame = false, has_ready_frame = false; // protected by <frame_mutex>
562 std::map<void *, new_frame_ready_callback_t> new_frame_ready_callbacks; // protected by <frame_mutex>
563 transition_names_updated_callback_t transition_names_updated_callback;
564 name_updated_callback_t name_updated_callback;
565 color_updated_callback_t color_updated_callback;
567 std::vector<std::string> last_transition_names;
568 std::string last_name, last_color;
570 OutputChannel output_channel[NUM_OUTPUTS];
572 std::thread mixer_thread;
573 std::thread audio_thread;
574 std::atomic<bool> should_quit{false};
575 std::atomic<bool> should_cut{false};
577 std::unique_ptr<ALSAOutput> alsa;
583 std::chrono::steady_clock::time_point frame_timestamp;
585 std::mutex audio_mutex;
586 std::condition_variable audio_task_queue_changed;
587 std::queue<AudioTask> audio_task_queue; // Under audio_mutex.
589 // For mode scanning.
590 bool is_mode_scanning[MAX_VIDEO_CARDS]{ false };
591 std::vector<uint32_t> mode_scanlist[MAX_VIDEO_CARDS];
592 unsigned mode_scanlist_index[MAX_VIDEO_CARDS]{ 0 };
593 std::chrono::steady_clock::time_point last_mode_scan_change[MAX_VIDEO_CARDS];
596 std::atomic<int64_t> metric_frames_output_total{0};
597 std::atomic<int64_t> metric_frames_output_dropped{0};
598 std::atomic<double> metric_start_time_seconds{0.0 / 0.0};
599 std::atomic<int64_t> metrics_memory_used_bytes{0};
600 std::atomic<double> metrics_memory_locked_limit_bytes{0.0 / 0.0};
603 extern Mixer *global_mixer;
604 extern bool uses_mlock;
606 #endif // !defined(_MIXER_H)