使用ffmpeg将YV12转换成RGB

看了下FFMPEG的pixfmt，没有YV12的格式

然后使用YUV420P（即I420）的方式去转换，发现颜色明显不对

看了下YV12和YUV420P的区别

只是U分量和V分量存储方式对换而已

现在要转换YV12为RGB24的话，我可以先将YV12->YUV420P

就是将YV12的数据的Y分量、U分量和V分量分别存到新YUV420P的Y分量、U分量和V分量处

YV12:

YY                                                               

YY                            

V

U

YUV420P:

YY

YY

U

V

关于YV12和NV12的格式说明可以看看别人的 http://blog.sina.com.cn/s/blog_784448d601015fiv.html

以及http://blog.csdn.net/leixiaohua1020/article/details/12234821

提供简单例子如下

static void CopyDataFromYV12ToYUV420P(uint8_t* pDst, const uint8_t* pSrc, int nWidth, int nHeight)

{

    int nYSize = nWidth * nHeight;

    int nVSize = nYSize / 4;

    int nUSize = nYSize / 4;

    int nSrcUOffset = nYSize;

    int nSrcVOffset = nSrcUOffset + nUSize;

    int nDstVOffset = nYSize;

    int nDstUOffset = nDstVOffset + nVSize;

    memcpy(pDst, pSrc, nYSize);

    memcpy((void*)((int)pDst + nDstVOffset), (void*)((int)pSrc + nSrcVOffset), nVSize);

    memcpy((void*)((int)pDst + nDstUOffset), (void*)((int)pSrc + nSrcUOffset), nUSize);

}

void GetRGB888FromYV12(const char* pYV12, const int nWidthIn, const int nHeightIn, \

                       char** pBufferOut, const int nWidthOut, const int nHeightOut)

{

    SwsContext* pConvert_ctx = NULL;

    AVFrame* pFrameIn = NULL;

    AVFrame* pFrameOut = NULL;

    uint8_t* pFrameBufferOut = NULL;

    int nFrameOutBufferSize = 0;

    uint8_t* pBufferIn = NULL;

    int nFrameInBufferSize = 0;

    pFrameIn = avcodec_alloc_frame();

    nFrameInBufferSize = avpicture_get_size(AV_PIX_FMT_YUV420P, nWidthIn, nHeightIn);

    pBufferIn = (uint8_t*)av_malloc(nFrameInBufferSize * sizeof(uint8_t));

    CopyDataFromYV12ToYUV420P(pBufferIn, (const uint8_t*)pYV12, nWidthIn, nHeightIn);

    avpicture_fill((AVPicture*)pFrameIn, (uint8_t*)pBufferIn, AV_PIX_FMT_YUV420P, nWidthIn, nHeightIn);

    pFrameOut = avcodec_alloc_frame();

    nFrameOutBufferSize = avpicture_get_size(PIX_FMT_RGB24, nWidthOut, nHeightOut);

    pFrameBufferOut = (uint8_t*)av_malloc(nFrameOutBufferSize * sizeof(uint8_t));

    avpicture_fill((AVPicture*)pFrameOut, pFrameBufferOut, PIX_FMT_RGB24, nWidthOut, nHeightOut);

    pConvert_ctx = sws_getContext(nWidthIn, nHeightIn, AV_PIX_FMT_YUV420P, \

                                   nWidthOut, nHeightOut, PIX_FMT_RGB24, \

                                  SWS_BICUBIC, NULL, NULL, NULL);

    sws_scale(pConvert_ctx, (const uint8_t* const*)pFrameIn->data, pFrameIn->linesize, 0,\

              nHeightIn, pFrameOut->data, pFrameOut->linesize);

    *pBufferOut = (char*)pFrameBufferOut;

    av_free(pBufferIn);

    av_free(pFrameOut);

    sws_freeContext(pConvert_ctx);

}