mp/include/decoder.h

#ifndef DECODER_H
#define DECODER_H
extern "C" {
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/imgutils.h"
}
#include <queue>
#include <condition_variable>
#include <mutex>

template<typename T>
	requires std::is_same_v<T, AVPacket> || std::is_same_v<T, AVFrame>
struct MediaQueue
{
	static constexpr int MAX_SIZE = 30;
	bool full = false;
	std::queue<T*> queue;
	std::condition_variable cv;
	std::mutex mut;

	uint32_t size;
	uint32_t count;

	MediaQueue() = default;
	bool isFill() const { return full; }
	bool push(const T* item);
	bool pop(T* item, bool block = false, bool quit = false);
};

template <typename T> requires std::is_same_v<T, AVPacket> || std::is_same_v<T, AVFrame>
bool MediaQueue<T>::push(const T* item) {
	if (item == nullptr) return false;
	if (count >= MAX_SIZE)
		return false;
	std::unique_lock lock(mut);
	if constexpr (std::is_same_v<T, AVPacket>) {
		auto temp = av_packet_alloc();
		av_packet_ref(temp, item);
		size += temp->size;
		queue.push(temp);
	}
	else if (std::is_same_v<T, AVFrame>) {
		auto temp = av_frame_alloc();
		av_frame_ref(temp, item);
		queue.push(temp);
	}
	count++;
	if (count >= MAX_SIZE) {
		full = true;
	}
	cv.notify_all();
	return true;
}

template <typename T> requires std::is_same_v<T, AVPacket> || std::is_same_v<T, AVFrame>
bool MediaQueue<T>::pop(T* item, bool block, bool quit) {
	std::unique_lock lock(mut);
	while (!quit) {
		if (!queue.empty()) {
			if constexpr (std::is_same_v<T, AVPacket>) {
				AVPacket* temp = queue.front();
				if (av_packet_ref(item, temp) < 0) {
					return false;
				}
				av_packet_unref(temp);
			}
			else if (std::is_same_v<T, AVFrame>) {
				AVFrame* temp = queue.front();
				if (av_frame_ref(item, temp) < 0) {
					return false;
				}
				av_frame_unref(temp);
			}
			queue.pop();
			count--;
			full = false;
			return true;
		}
		else if (block) {
			cv.wait(lock);
		}
		else {
			return false;
		}
	}
	return false;
}

struct VideoParam
{
	MediaQueue<AVPacket> packetQueue;
	MediaQueue<AVFrame> frameQueue;
	AVFormatContext* fmtCtx;
	AVCodecContext* codecCtx;
	int width;
	int height;
	int videoStreamIndex;

	bool eof = false;

	bool pause = false;
	bool quit = false;
};

void InitDecoder(const char* filepath, VideoParam& param);
void RequestPacket(VideoParam& param);
void RequestFrame(VideoParam& param);
#endif