我再次遇到ffmpeg的问题,我是ffmpeg的新手,我找不到最新的好教程...
这次,当我用ffmpeg播放视频时,它播放得太快,ffmpeg忽略了FPS,我不想用线程睡眠处理它,因为视频有不同的FPS。
我创建了一个线程,在那里你可以找到循环:
AVPacket framepacket;
while(av_read_frame(formatContext,&framepacket)>= 0){
pausecontrol.lock();
// Is it a video or audio frame¿?
if(framepacket.stream_index==gotVideoCodec){
int framereaded;
// Video? Ok
avcodec_decode_video2(videoCodecContext,videoFrame,&framereaded,&framepacket);
// Yeah, did we get it?
if(framereaded && doit){
AVRational millisecondbase = {1,1000};
int f_number = framepacket.dts;
int f_time = av_rescale_q(framepacket.dts,formatContext->streams[gotVideoCodec]->time_base,millisecondbase);
currentTime=f_time;
currentFrameNumber=f_number;
int stWidth = videoCodecContext->width;
int stHeight = videoCodecContext->height;
SwsContext *ctx = sws_getContext(stWidth, stHeight, videoCodecContext->pix_fmt, stWidth,
stHeight, PIX_FMT_RGB24, SWS_BICUBIC, NULL, NULL, NULL);
if(ctx!=0){
sws_scale(ctx,videoFrame->data,videoFrame->linesize,0,videoCodecContext->height,videoFrameRGB->data,videoFrameRGB->linesize);
QImage framecapsule=QImage(stWidth,stHeight,QImage::Format_RGB888);
for(int y=0;y<stHeight;y++){
memcpy(framecapsule.scanLine(y),videoFrameRGB->data[0]+y*videoFrameRGB->linesize[0],stWidth*3);
}
emit newFrameReady(framecapsule);
sws_freeContext(ctx);
}
}
}
if(framepacket.stream_index==gotAudioCodec){
// Audio? Ok
}
pausecontrol.unlock();
av_free_packet(&framepacket);
}
任何想法?
答案 0 :(得分:3)
最简单的解决方案是使用基于FPS值的延迟
firstFrame = true;
for(;;)
{
// decoding, color conversion, etc.
if (!firstFrame)
{
const double frameDuration = 1000.0 / frameRate;
duration_t actualDelay = get_local_time() - lastTime;
if (frameDuration > actualDelay)
sleep(frameDuration - actualDelay);
}
else
firstFrame = false;
emit newFrameReady(framecapsule);
lastTime = get_local_time();
}
get_local_time()
和duration_t
是抽象的。
更准确的方法是为每个帧使用时间戳,但想法是相同的