X-Git-Url: https://git.sesse.net/?p=nageru;a=blobdiff_plain;f=mixer.h;h=ff501b17635cd8830ba36e084754577cd75902b5;hp=c4f9e6bfebb2470fc41ddd12d4bec89665f346d6;hb=fa54f2630c56a1df0046923d6a77b1bd58abf240;hpb=dc508afd3b72b3c4212753c9a3e90f14d21f460e diff --git a/mixer.h b/mixer.h index c4f9e6b..ff501b1 100644 --- a/mixer.h +++ b/mixer.h @@ -23,6 +23,8 @@ #include #include +#include + #include "audio_mixer.h" #include "bmusb/bmusb.h" #include "defs.h" @@ -35,6 +37,7 @@ #include "theme.h" #include "timebase.h" #include "video_encoder.h" +#include "ycbcr_interpretation.h" class ALSAOutput; class ChromaSubsampler; @@ -51,6 +54,59 @@ class ResourcePool; class YCbCrInput; } // namespace movit +// A class to estimate the future jitter. Used in QueueLengthPolicy (see below). +// +// There are many ways to estimate jitter; I've tested a few ones (and also +// some algorithms that don't explicitly model jitter) with different +// parameters on some real-life data in experiments/queue_drop_policy.cpp. +// This is one based on simple order statistics where I've added some margin in +// the number of starvation events; I believe that about one every hour would +// probably be acceptable, but this one typically goes lower than that, at the +// cost of 2–3 ms extra latency. (If the queue is hard-limited to one frame, it's +// possible to get ~10 ms further down, but this would mean framedrops every +// second or so.) The general strategy is: Take the 99.9-percentile jitter over +// last 5000 frames, multiply by two, and that's our worst-case jitter +// estimate. The fact that we're not using the max value means that we could +// actually even throw away very late frames immediately, which means we only +// get one user-visible event instead of seeing something both when the frame +// arrives late (duplicate frame) and then again when we drop. +class JitterHistory { +private: + static constexpr size_t history_length = 5000; + static constexpr double percentile = 0.999; + static constexpr double multiplier = 2.0; + +public: + void register_metrics(const std::vector> &labels); + void unregister_metrics(const std::vector> &labels); + + void clear() { + history.clear(); + orders.clear(); + } + void frame_arrived(std::chrono::steady_clock::time_point now, int64_t frame_duration, size_t dropped_frames); + std::chrono::steady_clock::time_point get_expected_next_frame() const { return expected_timestamp; } + double estimate_max_jitter() const; + +private: + // A simple O(k) based algorithm for getting the k-th largest or + // smallest element from our window; we simply keep the multiset + // ordered (insertions and deletions are O(n) as always) and then + // iterate from one of the sides. If we had larger values of k, + // we could go for a more complicated setup with two sets or heaps + // (one increasing and one decreasing) that we keep balanced around + // the point, or it is possible to reimplement std::set with + // counts in each node. However, since k=5, we don't need this. + std::multiset orders; + std::deque::iterator> history; + + std::chrono::steady_clock::time_point expected_timestamp = std::chrono::steady_clock::time_point::min(); + + // Metrics. There are no direct summaries for jitter, since we already have latency summaries. + std::atomic metric_input_underestimated_jitter_frames{0}; + std::atomic metric_input_estimated_max_jitter_seconds{0.0 / 0.0}; +}; + // For any card that's not the master (where we pick out the frames as they // come, as fast as we can process), there's going to be a queue. The question // is when we should drop frames from that queue (apart from the obvious @@ -62,37 +118,39 @@ class YCbCrInput; // 2. We don't want to add more delay than is needed. // // Our general strategy is to drop as many frames as we can (helping for #2) -// that we think is safe for #1 given jitter. To this end, we set a lower floor N, -// where we assume that if we have N frames in the queue, we're always safe from -// starvation. (Typically, N will be 0 or 1. It starts off at 0.) If we have -// more than N frames in the queue after reading out the one we need, we head-drop -// them to reduce the queue. -// -// N is reduced as follows: If the queue has had at least one spare frame for -// at least 50 (master) frames (ie., it's been too conservative for a second), -// we reduce N by 1 and reset the timers. +// that we think is safe for #1 given jitter. To this end, we measure the +// deviation from the expected arrival time for all cards, and use that for +// continuous jitter estimation. // -// Whenever the queue is starved (we needed a frame but there was none), -// and we've been at N since the last starvation, N was obviously too low, -// so we increment it. We will never set N above 5, though. +// We then drop everything from the queue that we're sure we won't need to +// serve the output in the time before the next frame arrives. Typically, +// this means the queue will contain 0 or 1 frames, although more is also +// possible if the jitter is very high. class QueueLengthPolicy { public: QueueLengthPolicy() {} void reset(unsigned card_index) { this->card_index = card_index; - safe_queue_length = 1; - frames_with_at_least_one = 0; - been_at_safe_point_since_last_starvation = false; } - void update_policy(unsigned queue_length); // Call before picking out a frame, so 0 means starvation. + void register_metrics(const std::vector> &labels); + void unregister_metrics(const std::vector> &labels); + + // Call after picking out a frame, so 0 means starvation. + void update_policy(std::chrono::steady_clock::time_point now, + std::chrono::steady_clock::time_point expected_next_frame, + int64_t input_frame_duration, + int64_t master_frame_duration, + double max_input_card_jitter_seconds, + double max_master_card_jitter_seconds); unsigned get_safe_queue_length() const { return safe_queue_length; } private: - unsigned card_index; // For debugging only. - unsigned safe_queue_length = 1; // Called N in the comments. Can never go below 1. - unsigned frames_with_at_least_one = 0; - bool been_at_safe_point_since_last_starvation = false; + unsigned card_index; // For debugging and metrics only. + unsigned safe_queue_length = 0; // Can never go below zero. + + // Metrics. + std::atomic metric_input_queue_safe_length_frames{1}; }; class Mixer { @@ -139,10 +197,17 @@ public: return output_channel[output].get_display_frame(frame); } + // NOTE: Callbacks will be called with a mutex held, so you should probably + // not do real work in them. typedef std::function new_frame_ready_callback_t; - void set_frame_ready_callback(Output output, new_frame_ready_callback_t callback) + void add_frame_ready_callback(Output output, void *key, new_frame_ready_callback_t callback) { - output_channel[output].set_frame_ready_callback(callback); + output_channel[output].add_frame_ready_callback(key, callback); + } + + void remove_frame_ready_callback(Output output, void *key) + { + output_channel[output].remove_frame_ready_callback(key); } // TODO: Should this really be per-channel? Shouldn't it just be called for e.g. the live output? @@ -209,6 +274,9 @@ public: return theme->set_signal_mapping(signal, card); } + YCbCrInterpretation get_input_ycbcr_interpretation(unsigned card_index) const; + void set_input_ycbcr_interpretation(unsigned card_index, const YCbCrInterpretation &interpretation); + bool get_supports_set_wb(unsigned channel) const { return theme->get_supports_set_wb(channel); @@ -336,7 +404,8 @@ private: enum class CardType { LIVE_CARD, - FAKE_CAPTURE + FAKE_CAPTURE, + FFMPEG_INPUT }; void configure_card(unsigned card_index, bmusb::CaptureInterface *capture, CardType card_type, DeckLinkOutput *output); void set_output_card_internal(int card_index); // Should only be called from the mixer thread. @@ -354,12 +423,10 @@ private: void audio_thread_func(); void release_display_frame(DisplayFrame *frame); double pts() { return double(pts_int) / TIMEBASE; } - // Call this _before_ trying to pull out a frame from a capture card; - // it will update the policy and drop the right amount of frames for you. - void trim_queue(CaptureCard *card, unsigned card_index); + void trim_queue(CaptureCard *card, size_t safe_queue_length); HTTPD httpd; - unsigned num_cards; + unsigned num_cards, num_video_inputs; QSurface *mixer_surface, *h264_encoder_surface, *decklink_output_surface; std::unique_ptr resource_pool; @@ -401,6 +468,7 @@ private: struct CaptureCard { std::unique_ptr capture; bool is_fake_capture; + CardType type; std::unique_ptr output; // If this card is used for output (ie., output_card_index points to it), @@ -431,8 +499,30 @@ private: QueueLengthPolicy queue_length_policy; // Refers to the "new_frames" queue. int last_timecode = -1; // Unwrapped. + + JitterHistory jitter_history; + + // Metrics. + std::vector> labels; + std::atomic metric_input_received_frames{0}; + std::atomic metric_input_duped_frames{0}; + std::atomic metric_input_dropped_frames_jitter{0}; + std::atomic metric_input_dropped_frames_error{0}; + std::atomic metric_input_resets{0}; + std::atomic metric_input_queue_length_frames{0}; + + std::atomic metric_input_has_signal_bool{-1}; + std::atomic metric_input_is_connected_bool{-1}; + std::atomic metric_input_interlaced_bool{-1}; + std::atomic metric_input_width_pixels{-1}; + std::atomic metric_input_height_pixels{-1}; + std::atomic metric_input_frame_rate_nom{-1}; + std::atomic metric_input_frame_rate_den{-1}; + std::atomic metric_input_sample_rate_hz{-1}; }; + JitterHistory output_jitter_history; CaptureCard cards[MAX_VIDEO_CARDS]; // Protected by . + YCbCrInterpretation ycbcr_interpretation[MAX_VIDEO_CARDS]; // Protected by . AudioMixer audio_mixer; // Same as global_audio_mixer (see audio_mixer.h). bool input_card_is_master_clock(unsigned card_index, unsigned master_card_index) const; struct OutputFrameInfo { @@ -456,7 +546,8 @@ private: ~OutputChannel(); void output_frame(DisplayFrame frame); bool get_display_frame(DisplayFrame *frame); - void set_frame_ready_callback(new_frame_ready_callback_t callback); + void add_frame_ready_callback(void *key, new_frame_ready_callback_t callback); + void remove_frame_ready_callback(void *key); void set_transition_names_updated_callback(transition_names_updated_callback_t callback); void set_name_updated_callback(name_updated_callback_t callback); void set_color_updated_callback(color_updated_callback_t callback); @@ -469,7 +560,7 @@ private: std::mutex frame_mutex; DisplayFrame current_frame, ready_frame; // protected by bool has_current_frame = false, has_ready_frame = false; // protected by - new_frame_ready_callback_t new_frame_ready_callback; + std::map new_frame_ready_callbacks; // protected by transition_names_updated_callback_t transition_names_updated_callback; name_updated_callback_t name_updated_callback; color_updated_callback_t color_updated_callback; @@ -504,6 +595,5 @@ private: }; extern Mixer *global_mixer; -extern bool uses_mlock; #endif // !defined(_MIXER_H)