ffmpeg使用

        1.m_pIOContext = avio_alloc_context(m_pDecodeBuff,
                                          BUF_SIZE,          // internal Buffer and its size
                                          0,                // bWriteable (1=true,0=false)
                                          &m_CodeQueue,       // user data ; will be passed to our callback functions
                                          ReadData,
                                          NULL,                // Write callback function (not used in this example)
                                          NULL);

AVInputFormat *pInFmt = NULL;
   if (av_probe_input_buffer(m_pIOContext, &pInFmt, "", NULL, 0, 32*1024) < 0)
   {
       TRACE("probe failed!\n");
       return FALSE;
   }

3
   if(m_pFormatContex == NULL)
   {
       // Allocate the AVFormatContext:
       m_pFormatContex = avformat_alloc_context();
       if(m_pFormatContex == NULL)
       {
           TRACE("avformat alloc failed!\n");
           return FALSE;
       }
       // Set the IOContext:
       m_pFormatContex->pb = m_pIOContext;
   }

4.    if(avformat_open_input(&m_pFormatContex, "", pInFmt, NULL) != 0)
   {
       TRACE("avformat open failed.\n");
       return FALSE;
   }

    if(avformat_open_input(&m_pFormatContex, "", pInFmt, NULL) != 0)
   {
       TRACE("avformat open failed.\n");
       return FALSE;
   }

   if(av_find_stream_info(m_pFormatContex) < 0)
   {
       TRACE("could not fine stream.\n");
       return FALSE;
   }

av_dump_format(m_pFormatContex, 0, "", 0);

   for (int i = 0; i < m_pFormatContex->nb_streams; i++)
   {
       if ( (m_pFormatContex->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
           && (m_iVideoIndex < 0) )
       {
           m_iVideoIndex = i;
       }
   }

AVStream *pAVStream;
pAVStream = m_pFormatContex->streams[m_iVideoIndex];

    m_pCodecContextDecode = pAVStream->codec;
   std::cout<<"***codec_id = "<<m_pCodecContextDecode->codec_id<<endl;
   m_pCodecDecode = avcodec_find_decoder(m_pCodecContextDecode->codec_id);
   if (m_pCodecDecode == NULL)
   {
       TRACE("could not find video decoder!\n");
       return FALSE;
   }

9.
   if(m_pFrameDecode == NULL)
   {
       m_pFrameDecode = avcodec_alloc_frame();
       if(m_pFrameDecode == NULL)
       {
           TRACE("avcodec alloc frame failed!\n");
           return FALSE;
       }
   }

10.

av_init_packet(&m_PacketDecode);

11.

if (av_read_frame(m_pFormatContex, &m_PacketDecode) >= 0 )
       {
           int iSize = m_PacketDecode.size;
           if (m_PacketDecode.stream_index == m_iVideoIndex )
           {
               int got_picture = 0;
               int iRet = 0;

               iRet = avcodec_decode_video2(m_pCodecContextDecode, m_pFrameDecode, &got_picture, &m_PacketDecode);

12.if ( got_picture )

{

for ( j = 0; j != m_iHeight; j++)
                   {
                       memcpy(m_pCurrYuvBuff + iSize, m_pFrameDecode->data[0] + j * m_pFrameDecode->linesize[0], m_iWidth);
                       iSize += m_iWidth;
                   }

                   for (j = 0; j != m_iHeight / 2; j++)
                   {
                      memcpy(m_pCurrYuvBuff + iSize, m_pFrameDecode->data[2] + j * m_pFrameDecode->linesize[2], m_iWidth / 2);
                       iSize += m_iWidth / 2;
                   }

                   for (j = 0; j != m_iHeight / 2; j++)
                   {
                   memcpy(m_pCurrYuvBuff + iSize, m_pFrameDecode->data[1] + j * m_pFrameDecode->linesize[1], m_iWidth / 2);
                       iSize += m_iWidth / 2;
                   }
                   if(m_pDecodeCallBack != NULL)
                   {
                       m_pDecodeCallBack(m_pCurrYuvBuff, iSize, m_iWidth, m_iHeight, m_pContext);
                   }

}

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