音视频编解码:视频编解码基础1-FFmpeg结构与API摘要
音视频编解码:视频编解码基础2-FFmpeg解码实践
音视频编解码:视频编解码基础篇3-FFmpeg转码实践
音视频编解码:视频编解码基础篇4-FFmpeg解码播放
音视频编解码:视频编解码基础篇5-FFmpeg水印添加
一.FFmpeg解码播放
FFmpeg音视频编码流程.jpg
1首先接到上篇基础篇3的转码基础上继续.
在正常打开音视频流后开启读取音视频流线程(注意线程安全加解锁的多个细节点)
预制关键类和基本数据
@interface DJMediaFrame : NSObject
@property (nonatomic) CGFloat position;
@property (nonatomic) CGFloat duration;
@end
@interface DJAudioFrame : DJMediaFrame
@property (nonatomic)NSData *samples;
@end
@interface DJVideoFrame : DJMediaFrame
@property (nonatomic) NSInteger width;
@property (nonatomic) NSInteger height;
@end
@interface DJVideoFrameYUV : DJVideoFrame
@property (nonatomic)NSInteger dataLenth;
@property (nonatomic)UInt8* buffer;
/**
* 互斥锁
*/
NSCondition* _condition;
/**
* 用于装解码后的音视频数据
*/
AVFrame *_videoFrame;
AVFrame *_audioFrame;
/**
* 解码上下文
*/
AVFormatContext *_inFormatCtx;
/**
* 音视频数据流标志
*/
NSInteger _videoStream;
NSInteger _audioStream;
/**
* 非直播流控制播放位置进度
*/
CGFloat _duration;
/**
* 主被动退出线程条件标志
*/
BOOL _isErrorOccur;
BOOL volatile _closeStream;
BOOL _decoderRunning;
读取数据流线程操作
-(BOOL)startDecodeThread{
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
NSInvocationOperation *readOperation = [[NSInvocationOperation alloc] initWithTarget:wself selector:@selector(readFramesThreadProc) object:nil];
NSInvocationOperation *popOperation = [[NSInvocationOperation alloc] initWithTarget:wself selector:@selector(popFramesThreadProc) object:nil];
[queue addOperation:readOperation];
[queue addOperation:popOperation];
}
/**
* 读流数据，读数据的同时解码
*/
-(void)readFramesThreadProc{
@autoreleasepool {
_decoderRunning = true;
_isErrorOccur = false;
AVPacket packet;
av_init_packet(&packet);
NSLog(@"读数据流线程开始") UTF8String]);
while (!(_closeStream || _isErrorOccur)) {
_readFrameStartTime = av_gettime();
[_condition lock];
//具体问题具体分析可活动配置视频帧率
while (_decodeFrames.count > 0x30)
[_condition wait];
if (_closeStream) {
[_condition unlock];
break;
}
//读取数据
int result = av_read_frame(_inFormatCtx, &packet);
if (result < 0) {
_isErrorOccur = true;
[_condition unlock];
NSLog(@"数据读取错误 error->,%s", av_err2str(result));
break;
}
if (packet.stream_index ==_videoStream) {
[self decodeVideo:&packet];//处理视频数据包
} else if (packet.stream_index == _audioStream) {
[self decodeAudio:&packet];//处理音频数据包
}
[_condition unlock];
av_packet_unref(&packet);
}
_decoderRunning = false;
if (_isErrorOccur){
//如果出错做相应处理通知外部控制器
}
NSLog(@"读取数据线程结束，是否正常结束:(1：正常结束 0：网络错误结束) %d", _closeStream);
}
}
/**
* 取流数据
*/
-(void)popFramesThreadProc{
int64_t popCounts = 0;
int64_t prePopCounts = 0;
CGFloat playPosition = 0;
int spaceCount = 15;
@autoreleasepool {
NSLog(@"送数据线程开始");
while (!(_closeStream || _isErrorOccur)) {
@synchronized(_decodeFrames) {
if (_decodeFrames.count) {
DJMediaFrame* frame = [_decodeFrames firstObject];
if (enumFrameTypeAudio == frame.type) {
[self popAudioFrame:(DJAudioFrame*)frame];
[_decodeFrames removeObject:frame];
} else if (enumFrameTypeVideo == frame.type) {
popCounts ++;
playPosition = frame.position;
//音视频流同步操作暂不做说明
// [self checkAVPosition:playPosition];
[self popVideoFrame:(DJVideoFrame *)frame];
@synchronized (_videoFramesRecycle) {
[_videoFramesRecycle addObject:frame];
}
[_decodeFrames removeObject:frame];
}
}
//锁信号标志与解码同步30/s帧
if (_decodeFrames.count < 0x30){
[_condition signal];
}
}
}
NSLog(@"送数据线程结束");
}
}
音视频数据解码avcodec_send_packet avcodec_receive_frame
ffmpeg3版本的解码接口做了不少调整，之前的视频解码接口avcodec_decode_video2和avcodec_decode_audio4音频解码被设置为deprecated，对这两个接口做了合并，使用统一的接口。并且将音视频解码步骤分为了两步，第一步avcodec_send_packet，第二步avcodec_receive_frame，通过接口名字我们就可以知道第一步是发送编码数据包，第二步是接收解码后数据。
avcodec_send_packet avcodec_receive_frame成对出现但不是一一对应
-(void)decodeVideo:(AVPacket*)packet{
@autoreleasepool {
int result = avcodec_send_packet(_videoCodecCtx, packet);
if (result < 0) {
NSLog(@"发送视频编码数据包错误 error-> %s", av_err2str(result));
return;
}
while (avcodec_receive_frame(_videoCodecCtx, _videoFrame) >= 0) {
//视频录制处理
/* if (self.recorderbool) {
_errorOccur = ![self.assetWriter writeVideoFrame:_videoFrame];
if (_errorOccur) {
}else{
}
}*/
DJXVideoFrame *frame = [self handleVideoFrame];
if (frame) {
[self addDecodeDJMediaFrame:frame];
}
}
}
}
-(void)decodeAudio:(AVPacket*)packet{
@autoreleasepool {
int result = avcodec_send_packet(_audioCodecCtx, packet);
if (result < 0){
NSLog(@"发送音频编码数据包错误 error-> %s", av_err2str(result));
return;
}
while (avcodec_receive_frame(_audioCodecCtx, _audioFrame) >= 0) {
DJMediaFrame * frame = [self handleAudioFrame];
if (frame){
[self addDecodeDJMediaFrame:frame];
}
}
}
}
-(void)addDecodeDJMediaFrame:(DJMediaFrame*)frame{
@synchronized (_decodeFrames) {
NSInteger index = _decodeFrames.count - 1;
for (; index >= 0; index --) {
DJMediaFrame* tempFrame = [_decodeFrames objectAtIndex:index];
if (tempFrame.position < frame.position) break;
}
//向缓存容器添加视频帧
[_decodeFrames insertObject:frame atIndex:index + 1];
}
}
//不加 @autoreleasepool ,内存会得不到及时释放
-(void)popAudioFrame:(DJAudioFrame*)frame{
@autoreleasepool {
//1通过音频单元 AudioUnit 播放
//2通过音频队列AudioQueueRef播放
}
}
-(void)popVideoFrame:(DJVideoFrame*)frame{
@autoreleasepool {
//1通过YUV转RGB->UIimage 直接播放
//2将YUV处理通过OpenGLES渲染播放
}
}