FFmpegFrameSink.h

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#pragma once
 
// TODO
// FFmpeg has a lot of warnings
// Changing level to 2 on MSCV
// This does have the potential to break
// in the future and on other compilers
#ifdef _MSC_VER
#pragma warning(push, 2)
#endif
 
extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
}
 
#ifdef _MSC_VER
#pragma warning(pop)
#endif
 
#include "pch.h"
 
class FFmpegFrameSink {
private:
    mutable std::mutex initMutex;
    std::condition_variable initCV;
    bool initialized = false;
 
    mutable std::mutex dataMutex;
    std::condition_variable dataCV;
    long long lastFrame = 0;
 
protected:
    virtual void virtualInit(AVCodecContext *decoderContext) = 0;
    virtual void virtualOutputFrame(AVFrame *frame) = 0;
    virtual void getDataWithoutLock(std::vector<uint8_t> &data) = 0;
 
public:
    virtual ~FFmpegFrameSink() {}
 
    void init(AVCodecContext *decoderContext) {
        virtualInit(decoderContext);
        std::lock_guard<std::mutex> lock(initMutex);
        this->initialized = true;
        initCV.notify_all();
    }
 
    void waitForInit() {
        std::unique_lock<std::mutex> lock(initMutex);
        while (!initialized) {
            initCV.wait(lock);
        }
    }
 
    void outputFrame(AVFrame *frame) {
        std::lock_guard<std::mutex> lock(dataMutex);
        virtualOutputFrame(frame);
        lastFrame++;
        dataCV.notify_all();
    }
 
    long long getData(std::vector<uint8_t> &data) {
        std::lock_guard<std::mutex> lock(dataMutex);
        getDataWithoutLock(data);
        return lastFrame;
    }
 
    long long getNextData(std::vector<uint8_t> &data, long long lastFrameSeen) {
        std::unique_lock<std::mutex> lock(dataMutex);
        while (this->lastFrame == lastFrameSeen) {
            dataCV.wait(lock);
        }
        getDataWithoutLock(data);
        return this->lastFrame;
    }
 
    virtual AVMediaType getType() const = 0;
};