FFmpeg - 视频解码历程

FFmpeg - 视频解码过程

FFmpeg的文档做得不好，导致学会使用这个库是存在一定难度的。在对文件进行解码时，抄网上流传的例子就可以了。比如，常见的例子是这样的：

// 解析PES得到ES    TS_PesDecoder pesdec;    pesdec.Parse(m_iDemux.Payload(), m_iDemux.PayloadSize());    // AVPacket应包含的是ES数据    AVPacket avpkt;    av_init_packet(&avpkt);    avpkt.size = pesdec.m_nEsLength;    avpkt.data = pesdec.m_pEs;        if (avpkt.size == 0) return -1 ;    // 解AVPacket，得到图像数据AVFrame    while (avpkt.size &gt; 0)    {        int got_picture = 0;        int len = avcodec_decode_video2(m_pCodecContext, m_pPicture, &got_picture, &avpkt);        if (len &lt; 0)        {            fprintf(stderr, "Error while decoding frame...\n");            break;        }        if (got_picture)        {            int width = m_pCodecContext-&gt;width;            int height = m_pCodecContext-&gt;height;            VideoFrame frame;            frame.nWidth = width;            frame.nHeight = height;            frame.nPts = pesdec.m_nPts / 45; // in ms            AVPicture& pic_rgb = frame.iPic;            avpicture_alloc(&pic_rgb, PIX_FMT_RGB24, width, height);            // 用swscale库把YUYV420P转成RGB24            SwsContext* img_convert_ctx = sws_getContext(width, height, PIX_FMT_YUV420P,                width, height, PIX_FMT_RGB24,                SWS_BICUBIC, NULL, NULL, NULL);            sws_scale(img_convert_ctx,                m_pPicture-&gt;data, m_pPicture-&gt;linesize,                0, height,                pic_rgb.data, pic_rgb.linesize);            sws_freeContext(img_convert_ctx);            printf("Saving a frame ....\n");            m_iMutex.Lock();            m_lstFrames.push_back(frame);            m_iMutex.Unlock();                    return 1;        }        avpkt.size -= len;        avpkt.data += len;    }

FFmpeg - 视频解码历程

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