Add a system for queue length policies, so that we have as little as possible (but...

[nageru] / mixer.h

#ifndef _MIXER_H
#define _MIXER_H 1

// The actual video mixer, running in its own separate background thread.

#include <epoxy/gl.h>
#undef Success
#include <stdbool.h>
#include <stdint.h>

#include <movit/effect_chain.h>
#include <movit/flat_input.h>
#include <zita-resampler/resampler.h>
#include <atomic>
#include <condition_variable>
#include <cstddef>
#include <functional>
#include <memory>
#include <mutex>
#include <string>
#include <thread>
#include <vector>

#include "bmusb/bmusb.h"
#include "alsa_output.h"
#include "ebu_r128_proc.h"
#include "h264encode.h"
#include "httpd.h"
#include "pbo_frame_allocator.h"
#include "ref_counted_frame.h"
#include "ref_counted_gl_sync.h"
#include "resampling_queue.h"
#include "theme.h"
#include "timebase.h"
#include "stereocompressor.h"
#include "filter.h"
#include "input_state.h"
#include "correlation_measurer.h"

class H264Encoder;
class QSurface;
namespace movit {
class Effect;
class EffectChain;
class FlatInput;
class ResourcePool;
}  // namespace movit

namespace movit {
class YCbCrInput;
}
class QOpenGLContext;
class QSurfaceFormat;

// 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
// dropping if the 16-frame queue should become full), especially given that
// the frame rate could be lower or higher than the master (either subtly or
// dramatically). We have two (conflicting) demands:
//
//   1. We want to avoid starving the queue.
//   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.
//
// Whenever the queue is starved (we needed a frame but there was none), N was
// obviously too low, so we increment N. We will never set N above 5, though.
class QueueLengthPolicy {
public:
        QueueLengthPolicy() {}
        void reset(unsigned card_index) {
                this->card_index = card_index;
                safe_queue_length = 0;
                frames_with_at_least_one = 0;
        }

        void update_policy(int queue_length);  // Give in -1 for starvation.
        unsigned get_safe_queue_length() const { return safe_queue_length; }

private:
        unsigned card_index;  // For debugging only.
        unsigned safe_queue_length = 0;  // Called N in the comments.
        unsigned frames_with_at_least_one = 0;
};

class Mixer {
public:
        // The surface format is used for offscreen destinations for OpenGL contexts we need.
        Mixer(const QSurfaceFormat &format, unsigned num_cards);
        ~Mixer();
        void start();
        void quit();

        void transition_clicked(int transition_num);
        void channel_clicked(int preview_num);

        enum Output {
                OUTPUT_LIVE = 0,
                OUTPUT_PREVIEW,
                OUTPUT_INPUT0,  // 1, 2, 3, up to 15 follow numerically.
                NUM_OUTPUTS = 18
        };

        struct DisplayFrame {
                // The chain for rendering this frame. To render a display frame,
                // first wait for <ready_fence>, then call <setup_chain>
                // to wire up all the inputs, and then finally call
                // chain->render_to_screen() or similar.
                movit::EffectChain *chain;
                std::function<void()> setup_chain;

                // Asserted when all the inputs are ready; you cannot render the chain
                // before this.
                RefCountedGLsync ready_fence;

                // Holds on to all the input frames needed for this display frame,
                // so they are not released while still rendering.
                std::vector<RefCountedFrame> input_frames;

                // Textures that should be released back to the resource pool
                // when this frame disappears, if any.
                // TODO: Refcount these as well?
                std::vector<GLuint> temp_textures;
        };
        // Implicitly frees the previous one if there's a new frame available.
        bool get_display_frame(Output output, DisplayFrame *frame) {
                return output_channel[output].get_display_frame(frame);
        }

        typedef std::function<void()> new_frame_ready_callback_t;
        void set_frame_ready_callback(Output output, new_frame_ready_callback_t callback)
        {
                output_channel[output].set_frame_ready_callback(callback);
        }

        typedef std::function<void(float level_lufs, float peak_db,
                                   float global_level_lufs, float range_low_lufs, float range_high_lufs,
                                   float gain_staging_db, float final_makeup_gain_db,
                                   float correlation)> audio_level_callback_t;
        void set_audio_level_callback(audio_level_callback_t callback)
        {
                audio_level_callback = callback;
        }

        std::vector<std::string> get_transition_names()
        {
                return theme->get_transition_names(pts());
        }

        unsigned get_num_channels() const
        {
                return theme->get_num_channels();
        }

        std::string get_channel_name(unsigned channel) const
        {
                return theme->get_channel_name(channel);
        }

        int get_channel_signal(unsigned channel) const
        {
                return theme->get_channel_signal(channel);
        }

        int map_signal(unsigned channel)
        {
                return theme->map_signal(channel);
        }

        unsigned get_audio_source() const
        {
                return audio_source_channel;
        }

        void set_audio_source(unsigned channel)
        {
                audio_source_channel = channel;
        }

        void set_signal_mapping(int signal, int card)
        {
                return theme->set_signal_mapping(signal, card);
        }

        bool get_supports_set_wb(unsigned channel) const
        {
                return theme->get_supports_set_wb(channel);
        }

        void set_wb(unsigned channel, double r, double g, double b) const
        {
                theme->set_wb(channel, r, g, b);
        }

        void set_locut_cutoff(float cutoff_hz)
        {
                locut_cutoff_hz = cutoff_hz;
        }

        void set_locut_enabled(bool enabled)
        {
                locut_enabled = enabled;
        }

        float get_limiter_threshold_dbfs()
        {
                return limiter_threshold_dbfs;
        }

        float get_compressor_threshold_dbfs()
        {
                return compressor_threshold_dbfs;
        }

        void set_limiter_threshold_dbfs(float threshold_dbfs)
        {
                limiter_threshold_dbfs = threshold_dbfs;
        }

        void set_compressor_threshold_dbfs(float threshold_dbfs)
        {
                compressor_threshold_dbfs = threshold_dbfs;
        }

        void set_limiter_enabled(bool enabled)
        {
                limiter_enabled = enabled;
        }

        void set_compressor_enabled(bool enabled)
        {
                compressor_enabled = enabled;
        }

        void set_gain_staging_db(float gain_db)
        {
                std::unique_lock<std::mutex> lock(compressor_mutex);
                level_compressor_enabled = false;
                gain_staging_db = gain_db;
        }

        void set_gain_staging_auto(bool enabled)
        {
                std::unique_lock<std::mutex> lock(compressor_mutex);
                level_compressor_enabled = enabled;
        }

        void set_final_makeup_gain_db(float gain_db)
        {
                std::unique_lock<std::mutex> lock(compressor_mutex);
                final_makeup_gain_auto = false;
                final_makeup_gain = pow(10.0f, gain_db / 20.0f);
        }

        void set_final_makeup_gain_auto(bool enabled)
        {
                std::unique_lock<std::mutex> lock(compressor_mutex);
                final_makeup_gain_auto = enabled;
        }

        void schedule_cut()
        {
                should_cut = true;
        }

        void reset_meters();

        unsigned get_num_cards() const { return num_cards; }

        std::string get_card_description(unsigned card_index) const {
                assert(card_index < num_cards);
                return cards[card_index].capture->get_description();
        }

        std::map<uint32_t, VideoMode> get_available_video_modes(unsigned card_index) const {
                assert(card_index < num_cards);
                return cards[card_index].capture->get_available_video_modes();
        }

        uint32_t get_current_video_mode(unsigned card_index) const {
                assert(card_index < num_cards);
                return cards[card_index].capture->get_current_video_mode();
        }

        void set_video_mode(unsigned card_index, uint32_t mode) {
                assert(card_index < num_cards);
                cards[card_index].capture->set_video_mode(mode);
        }

        void start_mode_scanning(unsigned card_index);

        std::map<uint32_t, std::string> get_available_video_inputs(unsigned card_index) const {
                assert(card_index < num_cards);
                return cards[card_index].capture->get_available_video_inputs();
        }

        uint32_t get_current_video_input(unsigned card_index) const {
                assert(card_index < num_cards);
                return cards[card_index].capture->get_current_video_input();
        }

        void set_video_input(unsigned card_index, uint32_t input) {
                assert(card_index < num_cards);
                cards[card_index].capture->set_video_input(input);
        }

        std::map<uint32_t, std::string> get_available_audio_inputs(unsigned card_index) const {
                assert(card_index < num_cards);
                return cards[card_index].capture->get_available_audio_inputs();
        }

        uint32_t get_current_audio_input(unsigned card_index) const {
                assert(card_index < num_cards);
                return cards[card_index].capture->get_current_audio_input();
        }

        void set_audio_input(unsigned card_index, uint32_t input) {
                assert(card_index < num_cards);
                cards[card_index].capture->set_audio_input(input);
        }

private:
        void configure_card(unsigned card_index, const QSurfaceFormat &format, CaptureInterface *capture);
        void bm_frame(unsigned card_index, uint16_t timecode,
                FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
                FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format);
        void place_rectangle(movit::Effect *resample_effect, movit::Effect *padding_effect, float x0, float y0, float x1, float y1);
        void thread_func();
        void audio_thread_func();
        void process_audio_one_frame(int64_t frame_pts_int, int num_samples);
        void subsample_chroma(GLuint src_tex, GLuint dst_dst);
        void release_display_frame(DisplayFrame *frame);
        double pts() { return double(pts_int) / TIMEBASE; }

        HTTPD httpd;
        unsigned num_cards;

        QSurface *mixer_surface, *h264_encoder_surface;
        std::unique_ptr<movit::ResourcePool> resource_pool;
        std::unique_ptr<Theme> theme;
        std::atomic<unsigned> audio_source_channel{0};
        std::unique_ptr<movit::EffectChain> display_chain;
        GLuint cbcr_program_num;  // Owned by <resource_pool>.
        GLuint cbcr_vbo;  // Holds position and texcoord data.
        GLuint cbcr_position_attribute_index, cbcr_texcoord_attribute_index;
        std::unique_ptr<H264Encoder> h264_encoder;

        // Effects part of <display_chain>. Owned by <display_chain>.
        movit::FlatInput *display_input;

        int64_t pts_int = 0;  // In TIMEBASE units.

        std::mutex bmusb_mutex;
        struct CaptureCard {
                CaptureInterface *capture;
                std::unique_ptr<PBOFrameAllocator> frame_allocator;

                // Stuff for the OpenGL context (for texture uploading).
                QSurface *surface;
                QOpenGLContext *context;

                struct NewFrame {
                        RefCountedFrame frame;
                        int64_t length;  // In TIMEBASE units.
                        bool interlaced;
                        unsigned field;  // Which field (0 or 1) of the frame to use. Always 0 for progressive.
                        GLsync ready_fence;  // Whether frame is ready for rendering.
                        unsigned dropped_frames = 0;  // Number of dropped frames before this one.
                };
                std::queue<NewFrame> new_frames;
                bool should_quit = false;
                std::condition_variable new_frames_changed;  // Set whenever new_frames (or should_quit) is changed.

                QueueLengthPolicy queue_length_policy;  // Refers to the "new_frames" queue.

                // Accumulated errors in number of 1/TIMEBASE samples. If OUTPUT_FREQUENCY divided by
                // frame rate is integer, will always stay zero.
                unsigned fractional_samples = 0;

                std::mutex audio_mutex;
                std::unique_ptr<ResamplingQueue> resampling_queue;  // Under audio_mutex.
                int last_timecode = -1;  // Unwrapped.
                int64_t next_local_pts = 0;  // Beginning of next frame, in TIMEBASE units.
        };
        CaptureCard cards[MAX_CARDS];  // protected by <bmusb_mutex>

        InputState input_state;

        class OutputChannel {
        public:
                ~OutputChannel();
                void output_frame(DisplayFrame frame);
                bool get_display_frame(DisplayFrame *frame);
                void set_frame_ready_callback(new_frame_ready_callback_t callback);

        private:
                friend class Mixer;

                Mixer *parent = nullptr;  // Not owned.
                std::mutex frame_mutex;
                DisplayFrame current_frame, ready_frame;  // protected by <frame_mutex>
                bool has_current_frame = false, has_ready_frame = false;  // protected by <frame_mutex>
                new_frame_ready_callback_t new_frame_ready_callback;
                bool has_new_frame_ready_callback = false;
        };
        OutputChannel output_channel[NUM_OUTPUTS];

        std::thread mixer_thread;
        std::thread audio_thread;
        std::atomic<bool> should_quit{false};
        std::atomic<bool> should_cut{false};

        audio_level_callback_t audio_level_callback = nullptr;
        std::mutex compressor_mutex;
        Ebu_r128_proc r128;  // Under compressor_mutex.
        CorrelationMeasurer correlation;  // Under compressor_mutex.

        Resampler peak_resampler;
        std::atomic<float> peak{0.0f};

        StereoFilter locut;  // Default cutoff 120 Hz, 24 dB/oct.
        std::atomic<float> locut_cutoff_hz;
        std::atomic<bool> locut_enabled{true};

        // First compressor; takes us up to about -12 dBFS.
        StereoCompressor level_compressor;  // Under compressor_mutex. Used to set/override gain_staging_db if <level_compressor_enabled>.
        float gain_staging_db = 0.0f;  // Under compressor_mutex.
        bool level_compressor_enabled = true;  // Under compressor_mutex.

        static constexpr float ref_level_dbfs = -14.0f;  // Chosen so that we end up around 0 LU in practice.
        static constexpr float ref_level_lufs = -23.0f;  // 0 LU, more or less by definition.

        StereoCompressor limiter;
        std::atomic<float> limiter_threshold_dbfs{ref_level_dbfs + 4.0f};   // 4 dB.
        std::atomic<bool> limiter_enabled{true};
        StereoCompressor compressor;
        std::atomic<float> compressor_threshold_dbfs{ref_level_dbfs - 12.0f};  // -12 dB.
        std::atomic<bool> compressor_enabled{true};

        double final_makeup_gain = 1.0;  // Under compressor_mutex. Read/write by the user. Note: Not in dB, we want the numeric precision so that we can change it slowly.
        bool final_makeup_gain_auto = true;  // Under compressor_mutex.

        std::unique_ptr<ALSAOutput> alsa;

        struct AudioTask {
                int64_t pts_int;
                int num_samples;
        };
        std::mutex audio_mutex;
        std::condition_variable audio_task_queue_changed;
        std::queue<AudioTask> audio_task_queue;  // Under audio_mutex.

        // For mode scanning.
        bool is_mode_scanning[MAX_CARDS]{ false };
        std::vector<uint32_t> mode_scanlist[MAX_CARDS];
        unsigned mode_scanlist_index[MAX_CARDS]{ 0 };
        timespec last_mode_scan_change[MAX_CARDS];
};

extern Mixer *global_mixer;

#endif  // !defined(_MIXER_H)