av_register_all() ; AVFormatContext * pFormatCtx = avformat_alloc_context() ; if (avformat_open_input(&pFormatCtx,input_file.c_str(),nullptr,nullptr) < 0) qDebug() << "fail to find the stream\n" ; return ; if (avformat_find_stream_info(pFormatCtx,NULL) < 0) qDebug() << "fail to find the stream info\n" ; return ; // av_dump_format(pFormatCtx,0,input_file.c_str(),0) ; int video_stream_index = - 1 ; for (size_t i = 0 ;i < pFormatCtx->nb_streams ;++i ) if (pFormatCtx->streams [i] ->codec-> codec_type == AVMEDIA_TYPE_VIDEO) video_stream_index = i ; break ; if ( video_stream_index == - 1 ) qDebug() << "fail to find the video stream" ; return ; AVCodecContext * pCodecCtx = pFormatCtx->streams[video_stream_index]->codec ; AVCodec * pCodec = avcodec_find_decoder(pCodecCtx->codec_id) ; if ( pCodec == NULL) qDebug() << "fail to find the decoder\n" ; return ; if (avcodec_open2(pCodecCtx,pCodec,nullptr) < 0 ) qDebug() << "fail to open the decodec\n" ; return ; AVFrame * pFrame = av_frame_alloc() ; AVFrame * pframeRGB = av_frame_alloc() ; unsigned char * out_buffer = (unsigned char*)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_RGB32,pCodecCtx->width*scaleW,pCodecCtx->height*scaleH, 1 )) ; av_image_fill_arrays(pframeRGB->data,pframeRGB->linesize,out_buffer,AV_PIX_FMT_RGB32,pCodecCtx->width*scaleW,pCodecCtx->height*scaleH,1) ; AVPacket * pkt = av_packet_alloc() ; av_init_packet(pkt) ; SwsContext * pSwsCtx = sws_alloc_context() ; emit calSize(pCodecCtx->width*scaleW,pCodecCtx->height*scaleH) ; pSwsCtx = sws_getContext(pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt, pCodecCtx->width*scaleW,pCodecCtx->height*scaleH,AV_PIX_FMT_RGB32, SWS_BICUBIC,nullptr,nullptr,nullptr) ; int got_frame = 0 ; while(av_read_frame(pFormatCtx,pkt) >= 0) if (pkt-> stream_index == video_stream_index){ int ret = avcodec_decode_video2(pCodecCtx,pFrame,&got_frame,pkt) ; if (ret < 0) qDebug() << "fail to decode video\n" ; return ; if (got_frame > 0) sws_scale(pSwsCtx,(const unsigned char* const*)pFrame->data,pFrame->linesize,0,pCodecCtx->height,pframeRGB->data,pframeRGB->linesize) ; QImage image = QImage((unsigned char*)pframeRGB->data[ 0 ],pCodecCtx->width*scaleW,pCodecCtx->height*scaleH,QImage::Format_RGB32,nullptr,nullptr) ; emit genImage(image) ; usleep(30000) ; av_packet_unref(pkt) ; sws_freeContext(pSwsCtx) ; av_packet_free(&pkt) ; avformat_close_input(&pFormatCtx) ; avformat_free_context(pFormatCtx) ; emit palyFinished() ; 0.5倍大小

Conqueror712