使用ffmpeg实现单线程异步的视频播放器

自定义播放器系列

第一章 视频渲染
第二章 音频（push）播放
第三章 音频（pull）播放
第四章 实现时钟同步
第五章 实现通用时钟同步
第六章 实现播放器（本章）

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文章目录

• 自定义播放器系列
• 前言
• 一、播放流程
• 二、关键实现
• • 1.视频
  • • （1）解码
  • 2、音频
  • • （1）修正时钟
  • 3、时钟同步
  • • （1）、音频播放
    • （2）、视频播放
  • 4、异步读包
  • • （1）、async
    • （2）、await
    • （3）、消息处理
• 三、完整代码
• 四、使用示例
• 总结

---

前言

ffplay是一个不错的播放器，是基于多线程实现的，播放视频时一般至少有4个线程：读包线程、视频解码线程、音频解码线程、视频渲染线程。如果需要多路播放时，线程不可避免的有点多，比如需要播放8路视频时则需要32个线程，这样对性能的消耗还是比较大的。于是想到用单线程实现一个播放器，经过实践发现是可行的，播放本地文件时可以做到完全单线程、播放网络流时需要一个线程实现读包异步。

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一、播放流程

---

二、关键实现

因为是基于单线程的播放器有些细节还是要注意的。

1.视频

（1）解码

解码时需要注意设置多线程解码或者硬解以确保解码速度，因为在单线程中解码过慢则会导致视频卡顿。

//使用多线程解码
if (!av_dict_get(opts, "threads", NULL, 0))
	av_dict_set(&opts, "threads", "auto", 0);
//打开解码器
if (avcodec_open2(decoder->codecContext, codec, &opts) < 0) {
	LOG_ERROR("Could not open codec");
	av_dict_free(&opts);
	return ERRORCODE_DECODER_OPENFAILED;
}

或者根据情况设置硬解码器

codec = avcodec_find_decoder_by_name("hevc_qsv");
//打开解码器
if (avcodec_open2(decoder->codecContext, codec, &opts) < 0) {
	LOG_ERROR("Could not open codec");
	av_dict_free(&opts);
	return ERRORCODE_DECODER_OPENFAILED;
}

2、音频

（1）修正时钟

虽然音频的播放是基于流的，时钟也可以按照播放的数据量计算，但是出现丢包或者定位的一些情况时，按照数据量累计的方式会导致时钟不正确，所以在解码后的数据放入播放队列时应该进行时钟修正。synchronize_setClockTime参考《c语言 将音视频时钟同步封装成通用模块》。在音频解码之后：

//读取解码的音频帧
av_fifo_generic_read(play->audio.decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
//同步(修正)时钟
AVRational timebase = play->formatContext->streams[audio->decoder.streamIndex]->time_base;
//当前帧的时间戳
double pts = (double)frame->pts * timebase.num / timebase.den;
//减去播放队列剩余数据的时长就是当前的音频时钟
pts -= (double)av_audio_fifo_size(play->audio.playFifo) / play->audio.spec.freq;
synchronize_setClockTime(&play->synchronize, &play->synchronize.audio, pts);
//同步(修正)时钟--end
//写入播放队列
av_audio_fifo_write(play->audio.playFifo, (void**)&data, samples);

3、时钟同步

需要时钟同步的地方有3处，一处是音频解码后即上面的2、（2）。另外两处则是音频播放和视频渲染的地方。

（1）、音频播放

synchronize_updateAudio参考《c语言 将音视频时钟同步封装成通用模块》。

//sdl音频回调
static void audio_callback(void* userdata, uint8_t* stream, int len) {
   Play* play = (Play*)userdata;
   //需要写入的数据量
   samples = play->audio.spec.samples;
  //时钟同步，获取应该写入的数据量，如果是同步到音频，则需要写入的数据量始终等于应该写入的数据量。
   samples = synchronize_updateAudio(&play->synchronize, samples, play->audio.spec.freq);
   //略
}

（2）、视频播放

在视频渲染处实现如下代码，其中synchronize_updateVideo参考《c语言 将音视频时钟同步封装成通用模块》。

//---------------时钟同步--------------		
AVRational timebase = play->formatContext->streams[video->decoder.streamIndex]->time_base;
//计算视频帧的pts
double	pts = frame->pts * (double)timebase.num / timebase.den;
//视频帧的持续时间
double duration = frame->pkt_duration * (double)timebase.num / timebase.den;
double delay = synchronize_updateVideo(&play->synchronize, pts, duration);
if (delay > 0)
	//延时
{
	play->wakeupTime = getCurrentTime() + delay;
	return 0;
}
else if (delay < 0)
	//丢帧
{
	av_fifo_generic_read(video->decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
	av_frame_unref(frame);
	av_frame_free(&frame);
	return 0;
}
else
	//播放
{
	av_fifo_generic_read(video->decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
}
//---------------时钟同步--------------	end

4、异步读包

如果是本地文件单线程播放是完全没有问题的。但是播放网络流时，由于av_read_frame不是异步的，网络状况差时会导致延时过高影响到其他部分功能的正常进行，所以只能是将读包的操作放到子线程执行，这里采用async、await的思想实现异步。

（1）、async

将av_read_frame的放到线程池中执行。

//异步读取包，子线程中调用此方法
static int packet_readAsync(void* arg)
{
	Play* play = (Play*)arg;
	play->eofPacket = av_read_frame(play->formatContext, &play->packet);
	//回到播放线程处理包
	play_beginInvoke(play, packet_readAwait, play);
	return 0;
}

（2）、await

执行完成后通过消息队列通知播放器线程，将后续操作放在播放线程中执行

//异步读取包完成后的操作
static int packet_readAwait(void* arg)
{
	Play* play = (Play*)arg;
	if (play->eofPacket == 0)
	{
		if (play->packet.stream_index == play->video.decoder.streamIndex)
			//写入视频包队
		{
			AVPacket* packet = av_packet_clone(&play->packet);
			av_fifo_generic_write(play->video.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
		}
		else if (play->packet.stream_index == play->audio.decoder.streamIndex)
			//写入音频包队
		{
			AVPacket* packet = av_packet_clone(&play->packet);
			av_fifo_generic_write(play->audio.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
		}
		av_packet_unref(&play->packet);
	}
	else if (play->eofPacket == AVERROR_EOF)
	{
		play->eofPacket = 1;
		//写入空包flush解码器中的缓存
		AVPacket* packet = &play->packet;
		if (play->audio.decoder.fifoPacket)
			av_fifo_generic_write(play->audio.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
		if (play->video.decoder.fifoPacket)
			av_fifo_generic_write(play->video.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
	}
	else
	{
		LOG_ERROR("read packet erro!\n");
		play->exitFlag = 1;
		play->isAsyncReading = 0;
		return ERRORCODE_PACKET_READFRAMEFAILED;
	}
	play->isAsyncReading = 0;
	return 0;
}

（3）、消息处理

在播放线程中调用如下方法，处理事件，当await方法抛入消息队列后，就可以通过消息循环获取await方法在播放线程中执行。

//事件处理
static void play_eventHandler(Play* play) {
	PlayMessage msg;
	while (messageQueue_poll(&play->mq, &msg)) {
		switch (msg.type)
		{
		case PLAYMESSAGETYPE_INVOKE:
			SDL_ThreadFunction fn = (SDL_ThreadFunction)msg.param1;
			fn(msg.param2);
			break;
		}
	}
}

---

三、完整代码

完整代码c和c++都可以运行，使用ffmpeg4.3、sdl2。
main.c/cpp

#include <stdio.h>
#include <stdint.h>
#include "SDL.h"
#include<stdint.h>
#include<string.h>
#ifdef  __cplusplus
extern "C" {
#endif 
#include "libavformat/avformat.h"
#include "libavcodec/avcodec.h"
#include "libswscale/swscale.h"
#include "libavutil/imgutils.h"
#include "libavutil/time.h"
#include "libavutil/audio_fifo.h"
#include "libswresample/swresample.h"
#ifdef  __cplusplus
}
#endif 

/************************************************************************
* @Project:  	play
* @Decription:  视频播放器
* 这是一个播放器，基于单线程实现的播放器。如果是播放本地文件可以做到完全单线程，播放网络流则读取包的时候是异步的，当然
* 主流程依然是单线程。目前是读取包始终异步，未作判断本地文件同步读包处理。
* 对象池和线程池以及消息队列都是为了实现读
* @Verision:  	v0.0.0
* @Author:  	Xin Nie
* @Create:  	2022/12/12 21:21:00
* @LastUpdate:  2022/12/12 21:21:00
************************************************************************
* Copyright @ 2022. All rights reserved.
************************************************************************/
/// <summary>
/// 消息队列
/// </summary>
typedef struct {
	//队列长度
	int _capacity;
	//消息对象大小
	int _elementSize;
	//队列
	AVFifoBuffer* _queue;
	//互斥变量
	SDL_mutex* _mtx;
	//条件变量
	SDL_cond* _cv;
}MessageQueue;
/// <summary>
/// 对象池
/// </summary>
typedef struct {
	//对象缓存
	void* buffer;
	//对象大小
	int elementSize;
	//对象个数
	int arraySize;
	//对象使用状态1使用，0未使用
	int* _arrayUseState;
	//互斥变量
	SDL_mutex* _mtx;
	//条件变量
	SDL_cond* _cv;
}OjectPool;
/// <summary>
/// 线程池
/// </summary>
typedef struct {
	//最大线程数
	int maxThreadCount;
	//线程信息对象池
	OjectPool _pool;
}ThreadPool;
/// <summary>
/// 线程信息
/// </summary>
typedef struct {
	//所属线程池
	ThreadPool* _threadPool;
	//线程句柄
	SDL_Thread* _thread;
	//消息队列
	MessageQueue _queue;
	//线程回调方法
	SDL_ThreadFunction _fn;
	//线程回调参数
	void* _arg;
}ThreadInfo;
//解码器
typedef  struct {
	//解码上下文
	AVCodecContext* codecContext;
	//解码器
	const AVCodec* codec;
	//解码临时帧
	AVFrame* frame;
	//包队列
	AVFifoBuffer* fifoPacket;
	//帧队列
	AVFifoBuffer* fifoFrame;
	//流下标
	int	streamIndex;
	//解码结束标记
	int eofFrame;
}Decoder;
/// <summary>
/// 时钟对象
/// </summary>
typedef  struct {
	//起始时间
	double startTime;
	//当前pts
	double currentPts;
}Clock;
/// <summary>
/// 时钟同步类型
/// </summary>
typedef enum {
	//同步到音频
	SYNCHRONIZETYPE_AUDIO,
	//同步到视频
	SYNCHRONIZETYPE_VIDEO,
	//同步到绝对时钟
	SYNCHRONIZETYPE_ABSOLUTE
}SynchronizeType;
/// <summary>
/// 时钟同步对象
/// </summary>
typedef  struct {
	/// <summary>
	/// 音频时钟
	/// </summary>
	Clock audio;
	/// <summary>
	/// 视频时钟
	/// </summary>
	Clock video;
	/// <summary>
	/// 绝对时钟
	/// </summary>
	Clock absolute;
	/// <summary>
	/// 时钟同步类型
	/// </summary>
	SynchronizeType type;
	/// <summary>
	/// 估算的视频帧时长
	/// </summary>
	double estimateVideoDuration;
	/// <summary>
	/// 估算视频帧数
	/// </summary>
	double n;
}Synchronize;
//视频模块
typedef  struct {
	//解码器
	Decoder decoder;
	//输出格式
	enum AVPixelFormat forcePixelFormat;
	//重采样对象
	struct SwsContext* swsContext;
	//重采样缓存
	uint8_t* swsBuffer;
	//渲染器
	SDL_Renderer* sdlRenderer;
	//纹理
	SDL_Texture* sdlTexture;
	//窗口
	SDL_Window* screen;
	//窗口宽
	int screen_w;
	//窗口高
	int	screen_h;
	//播放结束标记
	int eofDisplay;
	//播放开始标记
	int sofDisplay;
}Video;

//音频模块
typedef  struct {
	//解码器
	Decoder decoder;
	//输出格式
	enum AVSampleFormat forceSampleFormat;
	//音频设备id
	SDL_AudioDeviceID audioId;
	//期望的音频设备参数
	SDL_AudioSpec wantedSpec;
	//实际的音频设备参数
	SDL_AudioSpec spec;
	//重采样对象
	struct SwrContext* swrContext;
	//重采样缓存
	uint8_t* swrBuffer;
	//播放队列
	AVAudioFifo* playFifo;
	//播放队列互斥锁
	SDL_mutex* mutex;
	//累积的待播放采样数
	int accumulateSamples;
	//音量
	int volume;
	//声音混合buffer
	uint8_t* mixBuffer;
	//播放结束标记
	int eofPlay;
	//播放开始标记
	int sofPlay;
}Audio;

//播放器
typedef  struct {
	//视频url
	char* url;
	//解复用上下文
	AVFormatContext* formatContext;
	//包
	AVPacket packet;
	//是否正在读取包
	int isAsyncReading;
	//包读取结束标记
	int eofPacket;
	//视频模块
	Video video;
	//音频模块
	Audio audio;
	//时钟同步
	Synchronize synchronize;
	//延时结束时间
	double wakeupTime;
	//播放一帧
	int step;
	//是否暂停
	int isPaused;
	//是否循环
	int isLoop;
	//退出标记
	int exitFlag;
	//消息队列
	MessageQueue mq;
}Play;

//播放消息类型
typedef enum {
	//调用方法
	PLAYMESSAGETYPE_INVOKE
}PlayMessageType;

//播放消息
typedef  struct {
	PlayMessageType type;
	void* param1;
	void* param2;
}PlayMessage;

//格式映射
static const struct TextureFormatEntry {
	enum AVPixelFormat format;
	int texture_fmt;
} sdl_texture_format_map[] = {
	{ AV_PIX_FMT_RGB8, SDL_PIXELFORMAT_RGB332 },
	{ AV_PIX_FMT_RGB444, SDL_PIXELFORMAT_RGB444 },
	{ AV_PIX_FMT_RGB555, SDL_PIXELFORMAT_RGB555 },
	{ AV_PIX_FMT_BGR555, SDL_PIXELFORMAT_BGR555 },
	{ AV_PIX_FMT_RGB565, SDL_PIXELFORMAT_RGB565 },
	{ AV_PIX_FMT_BGR565, SDL_PIXELFORMAT_BGR565 },
	{ AV_PIX_FMT_RGB24, SDL_PIXELFORMAT_RGB24 },
	{ AV_PIX_FMT_BGR24, SDL_PIXELFORMAT_BGR24 },
	{ AV_PIX_FMT_0RGB32, SDL_PIXELFORMAT_RGB888 },
	{ AV_PIX_FMT_0BGR32, SDL_PIXELFORMAT_BGR888 },
	{ AV_PIX_FMT_NE(RGB0, 0BGR), SDL_PIXELFORMAT_RGBX8888 },
	{ AV_PIX_FMT_NE(BGR0, 0RGB), SDL_PIXELFORMAT_BGRX8888 },
	{ AV_PIX_FMT_RGB32, SDL_PIXELFORMAT_ARGB8888 },
	{ AV_PIX_FMT_RGB32_1, SDL_PIXELFORMAT_RGBA8888 },
	{ AV_PIX_FMT_BGR32, SDL_PIXELFORMAT_ABGR8888 },
	{ AV_PIX_FMT_BGR32_1, SDL_PIXELFORMAT_BGRA8888 },
	{ AV_PIX_FMT_YUV420P, SDL_PIXELFORMAT_IYUV },
	{ AV_PIX_FMT_YUYV422, SDL_PIXELFORMAT_YUY2 },
	{ AV_PIX_FMT_UYVY422, SDL_PIXELFORMAT_UYVY },
	{ AV_PIX_FMT_NONE, SDL_PIXELFORMAT_UNKNOWN },
};

/// <summary>
/// 错误码
/// </summary>
typedef  enum {
	//无错误
	ERRORCODE_NONE = 0,
	//播放
	ERRORCODE_PLAY_OPENINPUTSTREAMFAILED = -0xffff,//打开输入流失败
	ERRORCODE_PLAY_VIDEOINITFAILED,//视频初始化失败
	ERRORCODE_PLAY_AUDIOINITFAILED,//音频初始化失败
	ERRORCODE_PLAY_LOOPERROR,//播放循环错误
	ERRORCODE_PLAY_READPACKETERROR,//解包错误
	ERRORCODE_PLAY_VIDEODECODEERROR,//视频解码错误
	ERRORCODE_PLAY_AUDIODECODEERROR,//音频解码错误
	ERRORCODE_PLAY_VIDEODISPLAYERROR,//视频播放错误
	ERRORCODE_PLAY_AUDIOPLAYERROR,//音频播放错误
	//解包
	ERRORCODE_PACKET_CANNOTOPENINPUTSTREAM,//无法代码输入流
	ERRORCODE_PACKET_CANNOTFINDSTREAMINFO,//查找不到流信息
	ERRORCODE_PACKET_DIDNOTFINDDANYSTREAM,//找不到任何流
	ERRORCODE_PACKET_READFRAMEFAILED,//读取包失败
	//解码
	ERRORCODE_DECODER_CANNOTALLOCATECONTEXT,//解码器上下文申请内存失败
	ERRORCODE_DECODER_SETPARAMFAILED,//解码器上下文设置参数失败
	ERRORCODE_DECODER_CANNOTFINDDECODER,//找不到解码器
	ERRORCODE_DECODER_OPENFAILED,//打开解码器失败
	ERRORCODE_DECODER_SENDPACKEDFAILED,//解码失败
	ERRORCODE_DECODER_MISSINGASTREAMTODECODE,//缺少用于解码的流
	//视频
	ERRORCODE_VIDEO_DECODERINITFAILED,//音频解码器初始化失败
	ERRORCODE_VIDEO_CANNOTGETSWSCONTEX,//无法获取ffmpeg swsContext
	ERRORCODE_VIDEO_IMAGEFILLARRAYFAILED,//将图像数据映射到数组时失败：av_image_fill_arrays
	ERRORCODE_VIDEO_CANNOTRESAMPLEAFRAME,//无法重采样视频帧
	ERRORCODE_VIDEO_MISSINGSTREAM,//缺少视频流
	//音频
	ERRORCODE_AUDIO_DECODERINITFAILED,//音频解码器初始化失败
	ERRORCODE_AUDIO_UNSUPORTDEVICESAMPLEFORMAT,//不支持音频设备采样格式
	ERRORCODE_AUDIO_SAMPLESSIZEINVALID,//采样大小不合法
	ERRORCODE_AUDIO_MISSINGSTREAM,//缺少音频流
	ERRORCODE_AUDIO_SWRINITFAILED,//ffmpeg swr重采样对象初始化失败
	ERRORCODE_AUDIO_CANNOTCONVERSAMPLE,//音频重采样失败
	ERRORCODE_AUDIO_QUEUEISEMPTY,//队列数据为空
	//帧
	ERRORCODE_FRAME_ALLOCFAILED,//初始化帧失败
	//队列
	ERRORCODE_FIFO_ALLOCFAILED,//初始化队列失败
	//sdl
	ERRORCODE_SDL_INITFAILED,//sdl初始化失败
	ERRORCODE_SDL_CANNOTCREATEMUTEX,//无法创建互斥锁
	ERRORCODE_SDL_CANNOTOPENDEVICE, //无法打开音频设备
	ERRORCODE_SDL_CREATEWINDOWFAILED,//创建窗口失败
	ERRORCODE_SDL_CREATERENDERERFAILED,//创建渲染器失败
	ERRORCODE_SDL_CREATETEXTUREFAILED,//创建纹理失败
	//内存
	ERRORCODE_MEMORY_ALLOCFAILED,//申请内存失败
	ERRORCODE_MEMORY_LEAK,//内存泄漏
	//参数
	ERRORCODE_ARGUMENT_INVALID,//参数不合法
	ERRORCODE_ARGUMENT_OUTOFRANGE,//超出范围
}ErrorCode;

/// <summary>
/// 日志等级
/// </summary>
typedef  enum {
	LOGLEVEL_NONE = 0,
	LOGLEVEL_INFO = 1,
	LOGLEVEL_DEBUG = 2,
	LOGLEVEL_TRACE = 4,
	LOGLEVEL_WARNNING = 8,
	LOGLEVEL_ERROR = 16,
	LOGLEVEL_ALL = LOGLEVEL_INFO | LOGLEVEL_DEBUG | LOGLEVEL_TRACE | LOGLEVEL_WARNNING | LOGLEVEL_ERROR
}
LogLevel;

//输出日志
#define LOGHELPERINTERNALLOG(message,level,...)  aclog(__FILE__,__FUNCTION__,__LINE__,level,message,##__VA_ARGS__)  
#define LOG_INFO(message,...) LOGHELPERINTERNALLOG(message,LOGLEVEL_INFO, ##__VA_ARGS__)
#define LOG_DEBUG(message,...) LOGHELPERINTERNALLOG(message,LOGLEVEL_DEBUG,##__VA_ARGS__)
#define LOG_TRACE(message,...) LOGHELPERINTERNALLOG(cmessage,LOGLEVEL_TRACE,##__VA_ARGS__)
#define LOG_WARNNING(message,...) LOGHELPERINTERNALLOG(message,LOGLEVEL_WARNNING,##__VA_ARGS__)
#define LOG_ERROR(message,...) LOGHELPERINTERNALLOG(message,LOGLEVEL_ERROR,##__VA_ARGS__)

static int logLevelFilter = LOGLEVEL_ALL;
static ThreadPool* _pool = NULL;

//写日志
void aclog(const char* fileName, const char* methodName, int line, LogLevel level, const char* message, ...) {
	if ((logLevelFilter & level) == 0)
		return;
	char dateTime[32];
	time_t tt = time(0);
	struct tm* t;
	va_list valist;
	char buf[512];
	char* pBuf = buf;
	va_start(valist, message);
	int size = vsnprintf(pBuf, sizeof(buf), message, valist);
	if (size > sizeof(buf))
	{
		pBuf = (char*)av_malloc(size + 1);
		vsnprintf(pBuf, size + 1, message, valist);
	}
	va_end(valist);
	t = localtime(&tt);
	sprintf(dateTime, "%04d-%02d-%02d %02d:%02d:%02d", t->tm_year + 1900, t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
	//在此处可替换为写文件
	printf("%s %d %d %s %s %d: %s\n", dateTime, level, SDL_ThreadID(), fileName, methodName, line, pBuf);
	if (pBuf != buf)
		av_free(pBuf);
}
//日志过滤，设为LOGLEVEL_NONE则不输出日志
void setLogFilter(LogLevel level) {
	logLevelFilter = level;
}


//初始化消息队列
int messageQueue_init(MessageQueue* _this, int capacity, int elementSize) {
	_this->_queue = av_fifo_alloc(elementSize * capacity);
	if (!_this->_queue)
		return ERRORCODE_MEMORY_ALLOCFAILED;
	_this->_mtx = SDL_CreateMutex();
	if (!_this->_mtx)
		return ERRORCODE_MEMORY_ALLOCFAILED;
	_this->_cv = SDL_CreateCond();
	if (!_this->_cv)
		return ERRORCODE_MEMORY_ALLOCFAILED;
	_this->_capacity = capacity;
	_this->_elementSize = elementSize;
	return 0;
}
//反初始化消息队列
void messageQueue_deinit(MessageQueue* _this) {
	if (_this->_queue)
		av_fifo_free(_this->_queue);
	if (_this->_cv)
		SDL_DestroyCond(_this->_cv);
	if (_this->_mtx)
		SDL_DestroyMutex(_this->_mtx);
	memset(_this, 0, sizeof(MessageQueue));
}

//推入消息
int messageQueue_push(MessageQueue* _this, void* msg) {
	int ret = 0;
	SDL_LockMutex(_this->_mtx);
	ret = av_fifo_generic_write(_this->_queue, msg, _this->_elementSize, NULL);
	SDL_CondSignal(_this->_cv);
	SDL_UnlockMutex(_this->_mtx);
	return  ret > 0;
}
//轮询序消息
int messageQueue_poll(MessageQueue* _this, void* msg) {
	SDL_LockMutex(_this->_mtx);
	int size = av_fifo_size(_this->_queue);
	if (size >= _this->_elementSize)
	{
		av_fifo_generic_read(_this->_queue, msg, _this->_elementSize, NULL);
	}
	SDL_UnlockMutex(_this->_mtx);
	return size;
}
//等待消息
void messageQueue_wait(MessageQueue* _this, void* msg) {
	SDL_LockMutex(_this->_mtx);
	while (1) {
		int size = av_fifo_size(_this->_queue);
		if (size >= _this->_elementSize)
		{
			av_fifo_generic_read(_this->_queue, msg, _this->_elementSize, NULL);
			break;
		}
		SDL_CondWait(_this->_cv, _this->_mtx);
	}
	SDL_UnlockMutex(_this->_mtx);
}

//初始化对象池
int ojectPool_init(OjectPool* _this, void* bufferArray, int elementSize, int arraySize)
{
	if (elementSize < 1 || arraySize < 1)
		return ERRORCODE_ARGUMENT_INVALID;
	_this->buffer = (unsigned char*)bufferArray;
	_this->elementSize = elementSize;
	_this->arraySize = arraySize;
	_this->_arrayUseState = (int*)av_mallocz(sizeof(int) * arraySize);
	if (!_this->_arrayUseState)
		return ERRORCODE_MEMORY_ALLOCFAILED;
	_this->_mtx = SDL_CreateMutex();
	if (!_this->_mtx)
		return ERRORCODE_MEMORY_ALLOCFAILED;
	_this->_cv = SDL_CreateCond();
	if (!_this->_cv)
		return ERRORCODE_MEMORY_ALLOCFAILED;
	return 0;
}
//反初始化对象池
void objectPool_deinit(OjectPool* _this)
{
	av_free(_this->_arrayUseState);
	if (_this->_cv)
		SDL_DestroyCond(_this->_cv);
	if (_this->_mtx)
		SDL_DestroyMutex(_this->_mtx);
	memset(_this, 0, sizeof(OjectPool));
}

//取出对象
void* objectPool_take(OjectPool* _this, int timeout) {
	void* element = NULL;
	SDL_LockMutex(_this->_mtx);
	while (1)
	{
		for (int i = 0; i < _this->arraySize; i++)
		{
			if (!_this->_arrayUseState[i])
			{
				element = &((Uint8*)_this->buffer)[i * _this->elementSize];
				_this->_arrayUseState[i] = 1;
				break;
			}
		}
		if (!element)
		{
			if (timeout == -1)
			{
				int ret = SDL_CondWait(_this->_cv, _this->_mtx);
				if (ret == -1)
				{
					LOG_ERROR("SDL_CondWait error");
					break;
				}
			}
			else
			{
				int ret = SDL_CondWaitTimeout(_this->_cv, _this->_mtx, timeout);
				if (ret != 0)
				{
					if (ret == -1)
					{
						LOG_ERROR("SDL_CondWait error");
					}
					break;
				}
			}
		}
		else
		{
			break;
		}
	}
	SDL_UnlockMutex(_this->_mtx);
	return element;
}

//归还对象
void objectPool_restore(OjectPool* _this, void* element) {
	SDL_LockMutex(_this->_mtx);
	for (int i = 0; i < _this->arraySize; i++)
	{
		if (_this->_arrayUseState[i] && &((Uint8*)_this->buffer)[i * _this->elementSize] == element)
		{
			SDL_CondSignal(_this->_cv);
			_this->_arrayUseState[i] = 0;
			break;
		}
	}
	SDL_UnlockMutex(_this->_mtx);
}

//初始化线程池
int threadPool_init(ThreadPool* _this, int maxThreadCount) {
	_this->maxThreadCount = maxThreadCount;
	return ojectPool_init(&_this->_pool, av_mallocz(sizeof(ThreadInfo) * maxThreadCount), sizeof(ThreadInfo), maxThreadCount);
}
//反初始化线程池
void threadPool_denit(ThreadPool* _this) {
	ThreadInfo* threads = (ThreadInfo*)_this->_pool.buffer;
	if (threads)
	{
		for (int i = 0; i < _this->maxThreadCount; i++)
		{
			int status;
			if (threads[i]._thread)
			{
				int msg = 0;
				messageQueue_push(&threads[i]._queue, &msg);
				SDL_WaitThread(threads[i]._thread, &status);
				messageQueue_deinit(&threads[i]._queue);
			}
		}
	}
	av_freep(&_this->_pool.buffer);
	objectPool_deinit(&_this->_pool);
}
//线程池，线程处理过程
int threadPool_threadProc(void* data)
{
	ThreadInfo* info = (ThreadInfo*)data;
	int msg = 1;
	while (msg) {
		info->_fn(info->_arg);
		objectPool_restore(&info->_threadPool->_pool, info);
		messageQueue_wait(&info->_queue, &msg);
	}
	return 0;
}
//在线程池中运行方法
void threadPool_run(ThreadPool* _this, SDL_ThreadFunction fn, void* arg) {
	ThreadInfo* info = (ThreadInfo*)objectPool_take(&_this->_pool, -1);
	info->_fn = fn;
	info->_arg = arg;
	if (info->_thread)
	{
		int msg = 1;
		messageQueue_push(&info->_queue, &msg);
	}
	else
	{
		info->_threadPool = _this;
		messageQueue_init(&info->_queue, 1, sizeof(int));
		info->_thread = SDL_CreateThread(threadPool_threadProc, "threadPool_threadProc", info);
	}
}

//在播放线程中运行方法
void play_beginInvoke(Play* _this, SDL_ThreadFunction fn, void* arg)
{
	PlayMessage msg;
	msg.type = PLAYMESSAGETYPE_INVOKE;
	msg.param1 = fn;
	msg.param2 = arg;
	messageQueue_push(&_this->mq, &msg);
}

//#include<chrono>
/// <summary>
/// 返回当前时间
/// </summary>
/// <returns>当前时间，单位秒，精度微秒</returns>
static double  getCurrentTime()
{
	//此处用的是ffmpeg的av_gettime_relative。如果没有ffmpeg环境，则可替换成平台获取时钟的方法：单位为秒，精度需要微妙，相对绝对时钟都可以。
	return av_gettime_relative() / 1000000.0;
	//return std::chrono::time_point_cast <std::chrono::nanoseconds>(std::chrono::high_resolution_clock::now()).time_since_epoch().count() / 1e+9;
}

/// <summary>
/// 重置时钟同步
/// 通常用于暂停、定位
/// </summary>
/// <param name="syn">时钟同步对象</param>
void synchronize_reset(Synchronize* syn) {
	SynchronizeType type = syn->type;
	memset(syn, 0, sizeof(Synchronize));
	syn->type = type;
}

/// <summary>
/// 获取主时钟
/// </summary>
/// <param name="syn">时钟同步对象</param>
/// <returns>主时钟对象</returns>
Clock* synchronize_getMasterClock(Synchronize* syn) {
	switch (syn->type)
	{
	case SYNCHRONIZETYPE_AUDIO:
		return &syn->audio;
	case SYNCHRONIZETYPE_VIDEO:
		return &syn->video;
	case SYNCHRONIZETYPE_ABSOLUTE:
		return &syn->absolute;
	default:
		break;
	}
	return 0;
}

/// <summary>
/// 获取主时钟的时间
/// </summary>
/// <param name="syn">时钟同步对象</param>
/// <returns>时间，单位s</returns>
double synchronize_getMasterTime(Synchronize* syn) {
	return getCurrentTime() - synchronize_getMasterClock(syn)->startTime;
}

/// <summary>
/// 设置时钟的时间
/// </summary>
/// <param name="syn">时钟同步对象</param>
/// <param name="pts">当前时间，单位s</param>
void synchronize_setClockTime(Synchronize* syn, Clock* clock, double pts)
{
	clock->currentPts = pts;
	clock->startTime = getCurrentTime() - pts;
}

/// <summary>
/// 获取时钟的时间
/// </summary>
/// <param name="syn">时钟同步对象</param>
/// <param name="clock">时钟对象</param>
/// <returns>时间，单位s</returns>
double synchronize_getClockTime(Synchronize* syn, Clock* clock)
{
	return  getCurrentTime() - clock->startTime;
}

/// <summary>
/// 更新视频时钟
/// </summary>
/// <param name="syn">时钟同步对象</param>
/// <param name="pts">视频帧pts,单位为s</param>
/// <param name="duration">视频帧时长,单位为s。缺省值为0，内部自动估算duration</param>
/// <returns>大于0则延时值为延时时长，等于0显示，小于0丢帧</returns>
double synchronize_updateVideo(Synchronize* syn, double pts, double duration)
{
	if (duration == 0)
		//估算duration
	{
		if (pts != syn->video.currentPts)
			syn->estimateVideoDuration = (syn->estimateVideoDuration * syn->n + pts - syn->video.currentPts) / (double)(syn->n + 1);
		duration = syn->estimateVideoDuration;
		//只估算最新3帧
		if (syn->n++ > 3)
			syn->estimateVideoDuration = syn->n = 0;
		if (duration == 0)
			duration = 0.1;
	}
	if (syn->video.startTime == 0)
	{
		syn->video.startTime = getCurrentTime() - pts;
	}
	//以下变量时间单位为s	
	//当前时间
	double currentTime = getCurrentTime() - syn->video.startTime;
	//计算时间差,大于0则late，小于0则early。
	double diff = currentTime - pts;
	double sDiff = 0;
	if (syn->type != SYNCHRONIZETYPE_VIDEO && synchronize_getMasterClock(syn)->startTime != 0)
		//同步到主时钟	
	{
		sDiff = syn->video.startTime - synchronize_getMasterClock(syn)->startTime;
		diff += sDiff;
	}
	//时间早了延时
	if (diff < -0.001)
	{
		if (diff < -0.1)
		{
			diff = -0.1;
		}
		//printf("video-time：%.3lfs audio-time:%.3lfs avDiff:%.4lfms early:%.4lfms  \n", getCurrentTime() - syn->video.startTime, getCurrentTime() - syn->audio.startTime, sDiff * 1000, diff * 1000);
		return -diff;
	}
	syn->video.currentPts = pts;
	//时间晚了丢帧，duration为一帧的持续时间，在一个duration内是正常时间，加一个duration作为阈值来判断丢帧。
	if (diff > 2 * duration)
	{
		//printf("time:%.3lfs avDiff %.4lfms late for:%.4lfms droped\n", pts, sDiff * 1000, diff * 1000);
		return -1;
	}
	//更新视频时钟
	printf("video-time：%.3lfs  audio-time:%.3lfs absolute-time:%.3lfs synDiff:%.4lfms diff:%.4lfms  \r", pts, getCurrentTime() - syn->audio.startTime, getCurrentTime() - syn->absolute.startTime, sDiff * 1000, diff * 1000);
	syn->video.startTime = getCurrentTime() - pts;
	if (syn->absolute.startTime == 0)
	{
		syn->absolute.startTime = syn->video.startTime;
	}
	return 0;
}

//double lastTime = 0;
/// <summary>
/// 更新音频时钟
/// </summary>
/// <param name="syn">时钟同步对象</param>
/// <param name="samples">采样数</param>
/// <param name="samplerate">采样率</param>
/// <returns>应该播放的采样数</returns>
int synchronize_updateAudio(Synchronize* syn, int samples, int samplerate) {

	if (syn->type != SYNCHRONIZETYPE_AUDIO && synchronize_getMasterClock(syn)->startTime != 0)
	{
		//同步到主时钟	
		double audioTime = getCurrentTime() - syn->audio.startTime;
		double diff = 0;
		diff = synchronize_getMasterTime(syn) - audioTime;
		int oldSamples = samples;
		if (fabs(diff) > 0.01) {
			samples += diff * samplerate;
		}
		if (samples < 0)
		{
			samples = 0;
		}
		if (samples > oldSamples * 2)
		{
			samples = oldSamples * 2;
		}
	}
	syn->audio.currentPts += (double)samples / samplerate;
	syn->audio.startTime = getCurrentTime() - syn->audio.currentPts;
	if (syn->absolute.startTime == 0)
	{
		syn->absolute.startTime = syn->audio.startTime;
	}
	return samples;
}

/// <summary>
/// 更新音频时钟，通过数据长度
/// </summary>
/// <param name="syn">时钟同步对象</param>
/// <param name="bytesSize">数据长度</param>
/// <param name="samplerate">采样率</param>
/// <param name="channels">声道数</param>
/// <param name="bitsPerSample">位深</param>
/// <returns>应该播放的数据长度</returns>
int synchronize_updateAudioByBytesSize(Synchronize* syn, size_t bytesSize, int samplerate, int channels, int bitsPerSample) {
	return synchronize_updateAudio(syn, bytesSize / (channels * bitsPerSample / 8), samplerate) * (bitsPerSample / 8) * channels;
}

//初始化解码器
static int decoder_init(Play* play, Decoder* decoder, int wantFifoPacketSize, int wantFifoFrameSize) {
	//创建解码上下文
	decoder->codecContext = avcodec_alloc_context3(NULL);
	AVDictionary* opts = NULL;
	if (decoder->codecContext == NULL)
	{
		LOG_ERROR("Could not allocate AVCodecContext");
		return ERRORCODE_DECODER_CANNOTALLOCATECONTEXT;
	}
	//获取解码器
	if (avcodec_parameters_to_context(decoder->codecContext, play->formatContext->streams[decoder->streamIndex]->codecpar) < 0)
	{
		LOG_ERROR("Could not init AVCodecContext");
		return ERRORCODE_DECODER_SETPARAMFAILED;
	}
	AVCodec* codec = avcodec_find_decoder(decoder->codecContext->codec_id);
	if (codec == NULL) {
		LOG_ERROR("Codec not found");
		return ERRORCODE_DECODER_CANNOTFINDDECODER;
	}
	//使用多线程解码
	if (!av_dict_get(opts, "threads", NULL, 0))
		av_dict_set(&opts, "threads", "auto", 0);
	//打开解码器
	if (avcodec_open2(decoder->codecContext, codec, &opts) < 0) {
		LOG_ERROR("Could not open codec");
		av_dict_free(&opts);
		return ERRORCODE_DECODER_OPENFAILED;
	}
	av_dict_free(&opts);
	//初始化临时帧
	decoder->frame = av_frame_alloc();
	if (!decoder->frame)
	{
		LOG_ERROR("Alloc avframe failed");
		return ERRORCODE_FRAME_ALLOCFAILED;
	}
	//初始化包队列
	decoder->fifoPacket = av_fifo_alloc(sizeof(AVPacket*) * wantFifoPacketSize);
	if (!decoder->fifoPacket)
	{
		LOG_ERROR("alloc packet fifo failed");
		return ERRORCODE_FIFO_ALLOCFAILED;
	}
	//初始化帧队列
	decoder->fifoFrame = av_fifo_alloc(sizeof(AVFrame*) * wantFifoFrameSize);
	if (!decoder->fifoFrame)
	{
		LOG_ERROR("alloc frame fifo failed");
		return ERRORCODE_FIFO_ALLOCFAILED;
	}
	return 0;
}
//清空解码队列
static void decoder_clear(Play* play, Decoder* decoder) {
	//清空包队列
	if (decoder->fifoPacket)
	{
		while (av_fifo_size(decoder->fifoPacket) > 0)
		{
			AVPacket* packet;
			av_fifo_generic_read(decoder->fifoPacket, &packet, sizeof(AVPacket*), NULL);
			if (packet != &play->packet)
			{
				av_packet_unref(packet);
				av_packet_free(&packet);
			}
		}
	}
	//清空帧队列
	if (decoder->fifoFrame)
	{
		while (av_fifo_size(decoder->fifoFrame) > 0)
		{
			AVFrame* frame;
			av_fifo_generic_read(decoder->fifoFrame, &frame, sizeof(AVFrame*), NULL);
			av_frame_unref(frame);
			av_frame_free(&frame);
		}
	}

	//清空解码器缓存
	if (decoder->codecContext)
	{
		avcodec_flush_buffers(decoder->codecContext);
	}
}
//反初始化解码器
static void decoder_deinit(Play* play, Decoder* decoder)
{
	decoder_clear(play, decoder);
	if (decoder->codecContext)
	{
		avcodec_close(decoder->codecContext);
		avcodec_free_context(&decoder->codecContext);
	}
	if (decoder->fifoPacket)
	{
		av_fifo_free(decoder->fifoPacket);
		decoder->fifoPacket = NULL;
	}
	if (decoder->fifoFrame)
	{
		av_fifo_free(decoder->fifoFrame);
		decoder->fifoFrame = NULL;
	}
	if (decoder->frame)
	{
		if (decoder->frame->format != -1)
		{
			av_frame_unref(decoder->frame);
		}
		av_frame_free(&decoder->frame);
	}
	decoder->eofFrame = 0;
}
//解码
static int decoder_decode(Play* play, Decoder* decoder) {
	int ret = 0;
	AVPacket* packet = NULL;
	if (decoder->streamIndex == -1)
	{
		LOG_ERROR("Decoder missing a stream");
		return ERRORCODE_DECODER_MISSINGASTREAMTODECODE;
	}
	if (av_fifo_space(decoder->fifoFrame) < 1)
		//帧队列已满
	{
		goto end;
	}
	//接收上次解码的帧
	while (avcodec_receive_frame(decoder->codecContext, decoder->frame) == 0) {
		AVFrame* frame = av_frame_clone(decoder->frame);
		av_frame_unref(decoder->frame);
		av_fifo_generic_write(decoder->fifoFrame, &frame, sizeof(AVFrame*), NULL);
		if (av_fifo_space(decoder->fifoFrame) < 1)
			//帧队列已满
		{
			goto end;
		}
	}
	if (av_fifo_size(decoder->fifoPacket) > 0)
		//包队列有数据，开始解码
	{
		av_fifo_generic_read(decoder->fifoPacket, &packet, sizeof(AVPacket*), NULL);
		//发送包
		if (avcodec_send_packet(decoder->codecContext, packet) < 0)
		{
			LOG_ERROR("Decode error");
			ret = ERRORCODE_DECODER_SENDPACKEDFAILED;
			goto end;
		}
		//接收解码的帧
		while (avcodec_receive_frame(decoder->codecContext, decoder->frame) == 0) {
			AVFrame* frame = av_frame_clone(decoder->frame);
			av_frame_unref(decoder->frame);
			av_fifo_generic_write(decoder->fifoFrame, &frame, sizeof(AVFrame*), NULL);
			if (av_fifo_space(decoder->fifoFrame) < 1)
				//帧队列已满
			{
				goto end;
			}
		}
	}
	if (play->eofPacket)
	{
		decoder->eofFrame = 1;
	}
end:
	if (packet && packet != &play->packet)
	{
		av_packet_unref(packet);
		av_packet_free(&packet);
	}
	return ret;
}



//音频设备播放回调
static void audio_callback(void* userdata, uint8_t* stream, int len) {
	Play* play = (Play*)userdata;
	int samples = 0;
	//读取队列中的音频数据，由于AVAudioFifo非线程安全，且是子线程触发此回调，所以需要加锁
	SDL_LockMutex(play->audio.mutex);
	if (!play->isPaused)
	{
		if (av_audio_fifo_size(play->audio.playFifo) >= play->audio.spec.samples)
		{
			int drain = 0;
			//需要写入的数据量
			samples = play->audio.spec.samples;
			//时钟同步，获取应该写入的数据量，如果是同步到音频，则需要写入的数据量始终等于应该写入的数据量。
			samples = synchronize_updateAudio(&play->synchronize, samples, play->audio.spec.freq);
			samples += play->audio.accumulateSamples;
			if (samples > av_audio_fifo_size(play->audio.playFifo))
			{
				play->audio.accumulateSamples = samples - av_audio_fifo_size(play->audio.playFifo);
				samples = av_audio_fifo_size(play->audio.playFifo);
			}
			else
			{
				play->audio.accumulateSamples = 0;
			}
			if (samples > play->audio.spec.samples)
				//比需要写入的数据量大，则丢弃一部分
			{
				drain = samples - play->audio.spec.samples;
				samples = play->audio.spec.samples;
			}
			if (play->audio.volume + SDL_MIX_MAXVOLUME != SDL_MIX_MAXVOLUME)
				//改变音量
			{
				if (!play->audio.mixBuffer)
				{
					play->audio.mixBuffer = (uint8_t*)av_malloc(len);
					if (!play->audio.mixBuffer)
					{
						LOG_ERROR("mixBuffer alloc failed");
						return;
					}
				}
				av_audio_fifo_read(play->audio.playFifo, (void**)&play->audio.mixBuffer, samples);
				int len2 = av_samples_get_buffer_size(0, play->audio.spec.channels, samples, play->audio.forceSampleFormat, 1);
				memset(stream, 0, len2);
				SDL_MixAudioFormat(stream, play->audio.mixBuffer, play->audio.spec.format, len2, play->audio.volume + SDL_MIX_MAXVOLUME);
			}
			else
				//直接写入
			{
				av_audio_fifo_read(play->audio.playFifo, (void**)&stream, samples);
			}
			av_audio_fifo_drain(play->audio.playFifo, drain);
		}
	}
	SDL_UnlockMutex(play->audio.mutex);
	//补充静音数据
	int fillSize = av_samples_get_buffer_size(0, play->audio.spec.channels, samples, play->audio.forceSampleFormat, 1);
	if (fillSize < 0)
		fillSize = 0;
	if (len - fillSize > 0)
	{
		memset(stream + fillSize, 0, len - fillSize);
	}

}
//初始化音频模块
static int audio_init(Play* play, Audio* audio) {
	//初始化解码器
	if (decoder_init(play, &audio->decoder, 600, 100) != 0)
	{
		LOG_ERROR("audio decoder init error");
		return 	ERRORCODE_AUDIO_DECODERINITFAILED;
	}
	//初始化sdl
	if ((SDL_WasInit(0) & (SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) == 0)
	{
		if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
			LOG_ERROR("Could not initialize SDL - %s", SDL_GetError());
			return ERRORCODE_SDL_INITFAILED;
		}
	}
	//打开音频设备
	audio->wantedSpec.channels = av_get_channel_layout_nb_channels(audio->decoder.codecContext->channel_layout);
	audio->wantedSpec.freq = audio->decoder.codecContext->sample_rate;
	audio->wantedSpec.format = AUDIO_F32SYS;
	audio->wantedSpec.silence = 0;
	audio->wantedSpec.samples = FFMAX(512, 2 << av_log2(audio->wantedSpec.freq / 30));
	audio->wantedSpec.callback = audio_callback;
	audio->wantedSpec.userdata = play;
	audio->audioId = SDL_OpenAudioDevice(NULL, 0, &audio->wantedSpec, &audio->spec, SDL_AUDIO_ALLOW_ANY_CHANGE);
	if (audio->audioId < 2)
	{
		LOG_ERROR("Open audio device error");
		return ERRORCODE_SDL_CANNOTOPENDEVICE;
	}
	//匹配音频格式
	switch (audio->spec.format)
	{
	case	AUDIO_S16SYS:
		audio->forceSampleFormat = AV_SAMPLE_FMT_S16;
		break;
	case	AUDIO_S32SYS:
		audio->forceSampleFormat = AV_SAMPLE_FMT_S32;
		break;
	case	AUDIO_F32SYS:
		audio->forceSampleFormat = AV_SAMPLE_FMT_FLT;
		break;
	default:

		LOG_ERROR("audio device format was not surported %d", (int)audio->spec.format);
		return ERRORCODE_AUDIO_UNSUPORTDEVICESAMPLEFORMAT;
	}
	//初始化音频帧队列的互斥锁
	audio->mutex = SDL_CreateMutex();
	if (!audio->mutex)
	{
		LOG_ERROR("alloc mutex failed");
		return ERRORCODE_SDL_CANNOTCREATEMUTEX;
	}
	//音频播放队列
	audio->playFifo = av_audio_fifo_alloc(audio->forceSampleFormat, audio->spec.channels, audio->spec.samples * 30);
	if (!audio->playFifo)
	{
		LOG_ERROR("alloc audio fifo failed");
		return ERRORCODE_FIFO_ALLOCFAILED;
	}
	//设备开启播放
	SDL_PauseAudioDevice(audio->audioId, 0);
	return 0;
}
//音频初始化
static void audio_deinit(Play* play, Audio* audio)
{
	if (audio->audioId >= 2)
	{
		SDL_PauseAudioDevice(audio->audioId, 1);
		SDL_CloseAudioDevice(audio->audioId);
		audio->audioId = 0;
	}
	if (audio->mutex)
	{
		SDL_DestroyMutex(audio->mutex);
		audio->mutex = NULL;
	}
	if (play->audio.playFifo)
	{
		av_audio_fifo_free(play->audio.playFifo);
		play->audio.playFifo = NULL;
	}
	if (audio->swrContext)
	{
		swr_free(&audio->swrContext);
	}
	if (audio->swrBuffer)
	{
		av_freep(&audio->swrBuffer);
	}
	if (audio->mixBuffer)
	{
		av_freep(&audio->mixBuffer);
	}
	decoder_deinit(play, &audio->decoder);
	audio->eofPlay = 0;
	audio->sofPlay = 0;
}


//音频播放
static int audio_play(Play* play, Audio* audio) {
	if (audio->decoder.streamIndex == -1)
	{
		LOG_ERROR("audio play missing audio stream");
		//没有音频流
		return ERRORCODE_AUDIO_MISSINGSTREAM;
	}
	if (play->video.decoder.streamIndex != -1 && !play->video.sofDisplay)
	{
		return 0;
	}
	while (av_fifo_size(play->audio.decoder.fifoFrame) > 0)
	{
		AVFrame* frame = NULL;
		uint8_t* data = NULL;
		int dataSize = 0;
		int samples = 0;
		av_fifo_generic_peek(play->audio.decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
		if (play->audio.forceSampleFormat != play->audio.decoder.codecContext->sample_fmt || play->audio.spec.freq != frame->sample_rate || play->audio.spec.channels != frame->channels)
			//重采样
		{
			//计算输入采样数
			int out_count = (int64_t)frame->nb_samples * play->audio.spec.freq / frame->sample_rate + 256;
			//计算输出数据大小
			int out_size = av_samples_get_buffer_size(NULL, play->audio.spec.channels, out_count, play->audio.forceSampleFormat, 0);
			//输入数据指针
			const uint8_t** in = (const uint8_t**)frame->extended_data;
			//输出缓冲区指针
			uint8_t** out = &play->audio.swrBuffer;
			int len2 = 0;
			if (out_size < 0) {
				LOG_ERROR("sample output size value %d was invalid", out_size);
				return ERRORCODE_AUDIO_SAMPLESSIZEINVALID;
			}
			if (!play->audio.swrContext)
				//初始化重采样对象
			{
				play->audio.swrContext = swr_alloc_set_opts(NULL, av_get_default_channel_layout(play->audio.spec.channels), play->audio.forceSampleFormat, play->audio.spec.freq, play->audio.decoder.codecContext->channel_layout, play->audio.decoder.codecContext->sample_fmt, play->audio.decoder.codecContext->sample_rate, 0, NULL);
				if (!play->audio.swrContext || swr_init(play->audio.swrContext) < 0) {
					LOG_ERROR("swr_alloc_set_opts or swr_init failed");
					return ERRORCODE_AUDIO_SWRINITFAILED;
				}
			}
			if (!play->audio.swrBuffer)
				//申请输出缓冲区
			{
				play->audio.swrBuffer = (uint8_t*)av_mallocz(out_size);
				if (!play->audio.swrBuffer)
				{
					LOG_ERROR("audio swr ouput buffer alloc failed");
					return ERRORCODE_MEMORY_ALLOCFAILED;
				}
			}
			//执行重采样
			len2 = swr_convert(play->audio.swrContext, out, out_count, in, frame->nb_samples);
			if (len2 < 0) {
				LOG_ERROR("swr_convert failed");
				return ERRORCODE_AUDIO_CANNOTCONVERSAMPLE;
			}
			//取得输出数据
			data = play->audio.swrBuffer;
			//输出数据长度
			dataSize = av_samples_get_buffer_size(0, play->audio.spec.channels, len2, play->audio.forceSampleFormat, 1);
			samples = len2;
		}
		else
			//无需重采样
		{
			data = frame->data[0];
			dataSize = av_samples_get_buffer_size(frame->linesize, frame->channels, frame->nb_samples, play->audio.forceSampleFormat, 0);
			samples = frame->nb_samples;
		}
		if (dataSize < 0)
		{
			LOG_ERROR("sample data size value %d was invalid", dataSize);
			return ERRORCODE_AUDIO_SAMPLESSIZEINVALID;
		}
		//写入播放队列
		SDL_LockMutex(play->audio.mutex);
		if (av_audio_fifo_space(play->audio.playFifo) >= samples)
		{
			//同步(修正)时钟
			AVRational timebase = play->formatContext->streams[audio->decoder.streamIndex]->time_base;
			//当前帧的时间戳
			double pts = (double)frame->pts * timebase.num / timebase.den;
			//减去播放队列剩余数据的时长就是当前的音频时钟
			pts -= (double)av_audio_fifo_size(play->audio.playFifo) / play->audio.spec.freq;
			//设置音频时钟
			synchronize_setClockTime(&play->synchronize, &play->synchronize.audio, pts);
			//同步(修正)时钟--end
			//写入播放队列
			av_audio_fifo_write(play->audio.playFifo, (void**)&data, samples);
			//解码队列的帧出队
			av_fifo_generic_read(play->audio.decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
			av_frame_unref(frame);
			av_frame_free(&frame);
			if (!audio->sofPlay)
				//标记开始
			{
				audio->sofPlay = 1;
			}
		}
		else
		{
			SDL_UnlockMutex(play->audio.mutex);
			break;
		}
		SDL_UnlockMutex(play->audio.mutex);
	}
	//计算睡眠延时
	SDL_LockMutex(play->audio.mutex);
	double canSleepTime = (double)av_audio_fifo_size(play->audio.playFifo) / play->audio.spec.freq;
	double wakeupTime = getCurrentTime() + canSleepTime;
	if (play->video.decoder.streamIndex == -1 || wakeupTime < play->wakeupTime)
	{
		play->wakeupTime = wakeupTime;
	}
	SDL_UnlockMutex(play->audio.mutex);
	if (av_fifo_size(play->audio.decoder.fifoFrame) < 1 && audio->decoder.eofFrame)
		//标记结束
	{
		audio->eofPlay = 1;
	}
	return 0;
}

//初始化视频模块
static int video_init(Play* play, Video* video) {
	//初始化解码器
	if (decoder_init(play, &video->decoder, 600, 1) != 0)
	{
		LOG_ERROR("video decoder init error");
		return ERRORCODE_VIDEO_DECODERINITFAILED;
	}
	//初始化sdl
	if ((SDL_WasInit(0) & (SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) == 0)
	{
		if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
			LOG_ERROR("Could not initialize SDL - %s", SDL_GetError());
			return ERRORCODE_SDL_INITFAILED;
		}
	}
	return 0;
}
//反初始化视频模块
static void video_deinit(Play* play, Video* video) {
	if (video->swsContext)
	{
		sws_freeContext(video->swsContext);
		video->swsContext = NULL;
	}
	if (video->swsBuffer)
	{
		av_free(video->swsBuffer);
		video->swsBuffer = NULL;
	}
	if (video->sdlTexture)
	{
		SDL_DestroyTexture(video->sdlTexture);
		video->sdlTexture = NULL;
	}
	if (video->sdlRenderer)
	{
		SDL_DestroyRenderer(video->sdlRenderer);
		video->sdlRenderer = NULL;
	}
	if (video->screen)
	{
		SDL_DestroyWindow(video->screen);
		video->screen = NULL;
	}
	decoder_deinit(play, &video->decoder);
	video->eofDisplay = 0;
	video->sofDisplay = 0;

}

//渲染到窗口
static int video_present(Play* play, Video* video, AVFrame* frame)
{
	
	SDL_Rect sdlRect;
	SDL_Rect sdlRect2;
	uint8_t* dst_data[4];
	int dst_linesize[4];

	if (!video->screen)
	{
		//创建窗口
		video->screen = SDL_CreateWindow("video play window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
			video->screen_w, video->screen_h,
			SDL_WINDOW_OPENGL);
		if (!video->screen) {
			LOG_ERROR("SDL: could not create window - exiting:%s\n", SDL_GetError());
			return ERRORCODE_SDL_CREATEWINDOWFAILED;
		}
	}
	if (!video->sdlRenderer)
		//初始化sdl纹理
	{
		video->sdlRenderer = SDL_CreateRenderer(video->screen, -1, 0);
		if (!video->sdlRenderer)
		{
			LOG_ERROR("Create sdl renderer error");
			return ERRORCODE_SDL_CREATERENDERERFAILED;
		}
		//获取合适的像素格式
		struct TextureFormatEntry format;
		format.format = AV_PIX_FMT_YUV420P;
		format.texture_fmt = SDL_PIXELFORMAT_IYUV;
		for (int i = 0; i < sizeof(sdl_texture_format_map) / sizeof(struct TextureFormatEntry); i++)
		{
			if (sdl_texture_format_map[i].format == video->decoder.codecContext->pix_fmt)
			{
				format = sdl_texture_format_map[i];
				break;
			}
		}
		video->forcePixelFormat = format.format;
		//创建和视频大小一样的纹理
		video->sdlTexture = SDL_CreateTexture(video->sdlRenderer, format.texture_fmt, SDL_TEXTUREACCESS_STREAMING, video->decoder.codecContext->width, video->decoder.codecContext->height);
		if (!video->sdlTexture)
		{
			LOG_ERROR("Create sdl texture error");
			return ERRORCODE_SDL_CREATETEXTUREFAILED;
		}
	}

	if (video->forcePixelFormat != video->decoder.codecContext->pix_fmt)
		//重采样-格式转换
	{
		video->swsContext = sws_getCachedContext(video->swsContext, video->decoder.codecContext->width, video->decoder.codecContext->height, video->decoder.codecContext->pix_fmt, video->decoder.codecContext->width, video->decoder.codecContext->height, video->forcePixelFormat, SWS_FAST_BILINEAR, NULL, NULL, NULL);
		if (!video->swsContext)
		{
			LOG_ERROR("sws_getCachedContext failed");
			return ERRORCODE_VIDEO_CANNOTGETSWSCONTEX;
		}
		if (!video->swsBuffer)
		{
			video->swsBuffer = (uint8_t*)av_malloc(av_image_get_buffer_size(video->forcePixelFormat, video->decoder.codecContext->width, video->decoder.codecContext->height, 64));
			if (video->swsBuffer)
			{
				LOG_ERROR("audio swr ouput buffer alloc failed");
				return ERRORCODE_MEMORY_ALLOCFAILED;
			}
		}
		if (av_image_fill_arrays(dst_data, dst_linesize, video->swsBuffer, video->forcePixelFormat, video->decoder.codecContext->width, video->decoder.codecContext->height, 1) < 0)
		{
			LOG_ERROR("sws_getCachedContext failed");
			return ERRORCODE_VIDEO_IMAGEFILLARRAYFAILED;
		}

		if (sws_scale(video->swsContext, frame->data, frame->linesize, 0, frame->height, dst_data, dst_linesize) < 0)
		{
			LOG_ERROR("Call sws_scale error");
			return ERRORCODE_VIDEO_CANNOTRESAMPLEAFRAME;
		}
	}
	else
		//无需重采样
	{
		memcpy(dst_data, frame->data, sizeof(uint8_t*) * 4);
		memcpy(dst_linesize, frame->linesize, sizeof(int) * 4);
	}

	//窗口区域
	sdlRect.x = 0;
	sdlRect.y = 0;
	sdlRect.w = video->screen_w;
	sdlRect.h = video->screen_h;
	//视频区域
	sdlRect2.x = 0;
	sdlRect2.y = 0;
	sdlRect2.w = video->decoder.codecContext->width;
	sdlRect2.h = video->decoder.codecContext->height;
	//渲染到sdl窗口
	SDL_RenderClear(video->sdlRenderer);
	SDL_UpdateYUVTexture(video->sdlTexture, &sdlRect2, dst_data[0], dst_linesize[0], dst_data[1], dst_linesize[1], dst_data[2], dst_linesize[2]);
	SDL_RenderCopy(video->sdlRenderer, video->sdlTexture, NULL, &sdlRect);
	SDL_RenderPresent(video->sdlRenderer);
}

//视频显示
static int video_display(Play* play, Video* video) {
	if (play->video.decoder.streamIndex == -1)
		//没有视频流
	{
		return ERRORCODE_VIDEO_MISSINGSTREAM;
	}
	if (play->audio.decoder.streamIndex != -1 && video->sofDisplay && !play->audio.sofPlay)
		return 0;
	AVFrame* frame = NULL;
	if (av_fifo_size(video->decoder.fifoFrame) > 0)
	{
		av_fifo_generic_peek(video->decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
		//---------------时钟同步--------------		
		AVRational timebase = play->formatContext->streams[video->decoder.streamIndex]->time_base;
		//计算视频帧的pts
		double	pts = frame->pts * (double)timebase.num / timebase.den;
		//视频帧的持续时间
		double duration = frame->pkt_duration * (double)timebase.num / timebase.den;
		double delay = synchronize_updateVideo(&play->synchronize, pts, duration);
		if (delay > 0)
			//延时
		{
			play->wakeupTime = getCurrentTime() + delay;
			return 0;
		}
		else if (delay < 0)
			//丢帧
		{
			av_fifo_generic_read(video->decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
			av_frame_unref(frame);
			av_frame_free(&frame);
			return 0;
		}
		else
			//播放
		{
			av_fifo_generic_read(video->decoder.fifoFrame, &frame, sizeof(AVFrame*), NULL);
		}
		//---------------时钟同步--------------	end
	}
	else if (video->decoder.eofFrame)
	{
		video->sofDisplay = 1;
		//标记结束
		video->eofDisplay = 1;
	}
	if (frame)
	{
		//渲染
		video_present(play, video, frame);
		av_frame_unref(frame);
		av_frame_free(&frame);
		if (!video->sofDisplay)
			video->sofDisplay = 1;
		if (play->step)
		{
			play->step--;
		}
	}
	return 0;
}
static int interrupt_cb(void* arg) {
	Play* play = (Play*)arg;
	return play->exitFlag;
}
//打开输入流
static int packet_open(Play* play) {
	//打开输入流
	play->formatContext = avformat_alloc_context();
	play->formatContext->interrupt_callback.callback = interrupt_cb;
	play->formatContext->interrupt_callback.opaque = play;
	if (avformat_open_input(&play->formatContext, play->url, NULL, NULL) != 0) {
		LOG_ERROR("Couldn't open input stream");
		return ERRORCODE_PACKET_CANNOTOPENINPUTSTREAM;
	}
	//查找输入流信息
	if (avformat_find_stream_info(play->formatContext, NULL) < 0) {
		LOG_ERROR("Couldn't find stream information");
		return ERRORCODE_PACKET_CANNOTFINDSTREAMINFO;
	}
	//ignore = 0;
	play->video.decoder.streamIndex = -1;
	//获取视频流
	for (unsigned i = 0; i < play->formatContext->nb_streams; i++)
		if (play->formatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
			play->video.decoder.streamIndex = i;
			break;
		}
	play->audio.decoder.streamIndex = -1;
	//获取音频流
	for (unsigned i = 0; i < play->formatContext->nb_streams; i++)
		if (play->formatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
			play->audio.decoder.streamIndex = i;
			break;
		}
	//没有找到任何流
	if (play->video.decoder.streamIndex == -1 && play->audio.decoder.streamIndex == -1) {
		LOG_ERROR("Didn't find any stream.");
		return ERRORCODE_PACKET_DIDNOTFINDDANYSTREAM;
	}
	play->eofPacket = 0;
	return 0;
}

//异步读取包完成后的操作
static int packet_readAwait(void* arg)
{
	Play* play = (Play*)arg;
	if (play->eofPacket == 0)
	{
		if (play->packet.stream_index == play->video.decoder.streamIndex)
			//写入视频包队
		{
			AVPacket* packet = av_packet_clone(&play->packet);
			av_fifo_generic_write(play->video.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
		}
		else if (play->packet.stream_index == play->audio.decoder.streamIndex)
			//写入音频包队
		{
			AVPacket* packet = av_packet_clone(&play->packet);
			av_fifo_generic_write(play->audio.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
		}
		av_packet_unref(&play->packet);
	}
	else if (play->eofPacket == AVERROR_EOF)
	{
		play->eofPacket = 1;
		//写入空包flush解码器中的缓存
		AVPacket* packet = &play->packet;
		if (play->audio.decoder.fifoPacket)
			av_fifo_generic_write(play->audio.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
		if (play->video.decoder.fifoPacket)
			av_fifo_generic_write(play->video.decoder.fifoPacket, &packet, sizeof(AVPacket*), NULL);
	}
	else
	{
		LOG_ERROR("read packet erro!\n");
		play->exitFlag = 1;
		play->isAsyncReading = 0;
		return ERRORCODE_PACKET_READFRAMEFAILED;
	}
	play->isAsyncReading = 0;
	return 0;
}

//异步读取包
static int packet_readAsync(void* arg)
{
	Play* play = (Play*)arg;
	play->eofPacket = av_read_frame(play->formatContext, &play->packet);
	//回到播放线程处理包
	play_beginInvoke(play, packet_readAwait, play);
	return 0;
}

//读取包
static int packet_read(Play* play) {
	if (play->isAsyncReading)
		return 0;
	if (play->eofPacket)
	{
		return 0;
	}
	if (play->video.decoder.streamIndex != -1 && av_fifo_space(play->video.decoder.fifoPacket) < 1)
		//视频包队列已满
	{
		return 0;
	}
	if (play->audio.decoder.streamIndex != -1 && av_fifo_space(play->audio.decoder.fifoPacket) < 1)
		//音频包队列已满
	{
		return 0;
	}
	if (!_pool)
		//初始化线程池
	{
		_pool = (ThreadPool*)av_mallocz(sizeof(ThreadPool));
		threadPool_init(_pool,32);
	}
	play->isAsyncReading = 1;
	//异步读取包
	threadPool_run(_pool, packet_readAsync, play);
	return 0;
}
static void play_eventHandler(Play* play);
//等待读包结束
static void packet_waitAsyncReadFinished(Play* play) {
	//确保异步操作结束
	while (play->isAsyncReading)
	{
		av_usleep(0.01 * 1000000);
		play_eventHandler(play);
	}
}

//关闭输入流
static void packet_close(Play* play) {
	packet_waitAsyncReadFinished(play);
	if (play->packet.data)
	{
		av_packet_unref(&play->packet);
	}
	if (play->formatContext)
	{
		avformat_close_input(&play->formatContext);
	}
}

//定位
static int packet_seek(Play* play, double time) {
	packet_waitAsyncReadFinished(play);
	return avformat_seek_file(play->formatContext, -1, INT64_MIN, time * AV_TIME_BASE, INT64_MAX, 0) >= 0;
}



//设置窗口大小
 void play_setWindowSize(Play* play, int width, int height) {
	play->video.screen_w = width;
	play->video.screen_h = height;
}


//定位
 void play_seek(Play* play, double time) {

	if (time < 0)
	{
		time = 0;
	}
	if (packet_seek(play, time))
	{
		//重置属性
		play->audio.accumulateSamples = 0;
		play->audio.sofPlay = 0;
		play->video.sofDisplay = 0;
		//清除缓存
		decoder_clear(play, &play->video.decoder);
		decoder_clear(play, &play->audio.decoder);
		avformat_flush(play->formatContext);
		if (play->audio.playFifo)
		{
			SDL_LockMutex(play->audio.mutex);
			av_audio_fifo_reset(play->audio.playFifo);
			synchronize_reset(&play->synchronize);
			SDL_UnlockMutex(play->audio.mutex);
		}
		else
		{
			synchronize_reset(&play->synchronize);
		}
		//暂停时需要播放一帧
		play->step = 1;
	}
}

//暂停
 void play_pause(Play* play, int isPaused) {
	if (play->isPaused == isPaused)
		return;
	if (!isPaused)
	{
		play->audio.sofPlay = 0;
		play->video.sofDisplay = 0;
		synchronize_reset(&play->synchronize);
	}
	play->isPaused = isPaused;
}

//静音
 void play_setVolume(Play* play, int value) {
	//移动到0作为最大音量。则初始化memset后不需要设置默认音量。
	if (value < 0)
		value = 0;
	value -= SDL_MIX_MAXVOLUME;
	if (play->audio.volume == value)
		return;
	play->audio.volume = value;
}

 int play_getVolume(Play* play) {
	return play->audio.volume + SDL_MIX_MAXVOLUME;
}

//事件处理
static void play_eventHandler(Play* play) {

	PlayMessage msg;
	while (messageQueue_poll(&play->mq, &msg)) {
		switch (msg.type)
		{
		case PLAYMESSAGETYPE_INVOKE:
			SDL_ThreadFunction fn = (SDL_ThreadFunction)msg.param1;
			fn(msg.param2);
			break;
		}
	}

	//处理窗口消息
	SDL_Event sdl_event;
	if (SDL_PollEvent(&sdl_event))
	{
		switch (sdl_event.type)
		{
		case SDL_WINDOWEVENT:
			if (sdl_event.window.event == SDL_WINDOWEVENT_CLOSE)
				play->exitFlag = 1;
			break;
		case SDL_KEYDOWN:
			switch (sdl_event.key.keysym.sym) {
			case SDLK_UP:
				play_setVolume(play, play_getVolume(play) + 20);
				break;
			case SDLK_DOWN:
				play_setVolume(play, play_getVolume(play) -20);
				break;
			case SDLK_LEFT:
				play_seek(play, synchronize_getMasterTime(&play->synchronize) - 10);
				break;
			case SDLK_RIGHT:
				play_seek(play, synchronize_getMasterTime(&play->synchronize) + 10);
				break;
			case SDLK_SPACE:
				play_pause(play, !play->isPaused);
				break;
			default:
				break;
			}
			break;
		}
	}
}

//播放循环
static int play_loop(Play* play)
{
	int ret = 0;
	double remainingTime = 0;
	while (!play->exitFlag)
	{
		if (!play->isPaused || play->step)
		{
			//解复用
			if ((ret = packet_read(play)) != 0)
			{
				LOG_ERROR("read packet error");
				ret = ERRORCODE_PLAY_READPACKETERROR;
				break;
			}
			//视频解码
			if ((ret = decoder_decode(play, &play->video.decoder)) != 0)
			{
				LOG_ERROR("video decode error");
				ret = ERRORCODE_PLAY_VIDEODECODEERROR;
				break;
			}
			//音频解码
			if ((ret = decoder_decode(play, &play->audio.decoder)) != 0)
			{
				LOG_ERROR("audio decode error");
				ret = ERRORCODE_PLAY_AUDIODECODEERROR;
				break;
			}
			//延时等待
			remainingTime = (play->wakeupTime - getCurrentTime()) / 2;
			if (remainingTime > 0)
			{
				av_usleep(remainingTime * 1000000);
			}
			//视频显示
			if ((ret = video_display(play, &play->video)) != 0)
			{
				LOG_ERROR("video display error");
				ret = ERRORCODE_PLAY_VIDEODISPLAYERROR;
				break;
			}
			//音频播放
			if ((ret = audio_play(play, &play->audio)) != 0)
			{
				LOG_ERROR("audio play error");
				ret = ERRORCODE_PLAY_AUDIOPLAYERROR;
				break;
			}
			//检查结尾
			if ((play->video.decoder.streamIndex == -1 || play->video.eofDisplay) && (play->audio.decoder.streamIndex == -1 || play->audio.eofPlay))
			{
				if (!play->isLoop)
					break;
				//循环播放，定位到起点
				play->eofPacket = 0;
				play->audio.decoder.eofFrame = 0;
				play->video.decoder.eofFrame = 0;
				play->audio.eofPlay = 0;
				play->video.eofDisplay = 0;
				play_seek(play, 0);
				continue;
			}
		}
		else
		{
			av_usleep(0.01 * 1000000);
		}
		//处理消息
		play_eventHandler(play);
	}

	return ret;
}

/// <summary>
/// 播放
/// 单线程阻塞播放
/// </summary>
/// <param name="play">播放器对象</param>
/// <param name="url">输入流的地址，可以是本地路径、http、https、rtmp、rtsp等</param>
/// <returns>错误码，0表示无错误</returns>
int play_exec(Play* play, const char* url) {
	int ret = 0;
	play->url = (char*)url;
	//打开输入流
	if ((ret = packet_open(play)) != 0)
	{
		LOG_ERROR("open input error");
		ret = ERRORCODE_PLAY_OPENINPUTSTREAMFAILED;
		goto end;
	}
	//初始化视频模块
	if (play->video.decoder.streamIndex != -1)
	{
		if ((ret = video_init(play, &play->video)) != 0)
		{
			LOG_ERROR("init video error");
			ret = ERRORCODE_PLAY_VIDEOINITFAILED;
			goto end;
		}
	}
	//初始化音频模块
	if (play->audio.decoder.streamIndex != -1)
	{
		if ((ret = audio_init(play, &play->audio)) != 0)
		{
			LOG_ERROR("init audio error");
			ret = ERRORCODE_PLAY_AUDIOINITFAILED;
			goto end;
		}
	}
	else
	{
		play->synchronize.type = SYNCHRONIZETYPE_ABSOLUTE;
	}
	//初始化消息队列
	if ((ret = messageQueue_init(&play->mq, 500, sizeof(PlayMessage))) != 0)
	{
		LOG_ERROR("open input error");
		ret = ERRORCODE_PLAY_OPENINPUTSTREAMFAILED;
		goto end;
	}
	//进入播放循环进行：解码-渲染-播放
	if ((ret = play_loop(play)) != 0)
	{
		ret = ERRORCODE_PLAY_LOOPERROR;
	}
end:
	//销毁资源	
	if (play->video.decoder.streamIndex != -1)
	{
		video_deinit(play, &play->video);
	}
	if (play->audio.decoder.streamIndex != -1)
	{
		audio_deinit(play, &play->audio);
	}
	packet_close(play);
	synchronize_reset(&play->synchronize);
	messageQueue_deinit(&play->mq);
	play->url = NULL;
	play->exitFlag = 0;
	return ret;
}
/// <summary>
/// 退出播放
/// </summary>
/// <param name="play">播放器对象</param>
void play_exit(Play* play)
{
	play->exitFlag = 1;
}

---

四、使用示例

int main(int argc, char** argv) {
	Play play;
	//memset相当于初始化
	memset(&play, 0, sizeof(Play));
	play_setWindowSize(&play, 640, 360);
	play.isLoop = 1;
	//单线程阻塞播放。左快退、右快进、上下调音量、空格暂停。
	return play_exec(&play, "D:\\test.mp4");
}

---

总结

以上就是今天要讲的内容，本文的播放器验证了单线程播放是可行的，尤其是播放本地文件可以做到完全单线程，那这样对于实现视频剪辑工具就有很大的帮助了，每多一条轨道只需要增加一个线程。而且采用异步读包之后也能正常播放网络流，2个线程播放视频依然比ffplay要优化。