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• libav C++ sw_scale returns variable byte size of BGR24 buffer

  6 mars 2021, par igor

  I'm trying to convert my local /dev/video0 cam to BGR24 format. It works if I resize the image (although not 100% of the time, more like 85% of the time), but I'd like to keep the same size as input video.

  


  I initialize BGR image like so including the sws context :

  


  AVPixelFormat outputPixFormat = AV_PIX_FMT_BGR24;

    AVFrame* pFrameBGR = av_frame_alloc();
    pFrameBGR->width = decoder->video_codec_context->width;
    pFrameBGR->height = decoder->video_codec_context->height;
    pFrameBGR->format = outputPixFormat;

    int alloRet = av_image_alloc(pFrameBGR->data, pFrameBGR->linesize, decoder->video_codec_context->width, decoder->video_codec_context->height, outputPixFormat, 1);
    if (alloRet < 0) {
        logging("failed to allocate image");
        return -1;
    }

    struct SwsContext *sws_ctx = NULL;

    sws_ctx = sws_getContext(decoder->video_codec_context->width,
    decoder->video_codec_context->height,
    decoder->video_codec_context->pix_fmt,
    decoder->video_codec_context->width,
    decoder->video_codec_context->height,
    outputPixFormat,
    SWS_DIRECT_BGR,
    0,
    0,
    0
    );


  


  This is the portion of my decoding loop :

  


  int response = avcodec_send_packet(pCodecContext, pPacket);
    if (response < 0) {
        logging("Error while sending a packet to decoder: %s", av_err2str(response));
        return response;
    }

    while (response >= 0) {
        response = avcodec_receive_frame(pCodecContext, pFrame);
         if (response == AVERROR(EAGAIN) || response == AVERROR_EOF) {
            break;
        } else if (response < 0) {
            logging("Error while receiving a frame from the decoder: %s", av_err2str(response));
            return response;
        }
        if (response >= 0) {

            sws_scale(sws_ctx,  (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecContext->height, pFrameBGR->data, pFrameBGR->linesize);



  


  THe question is how to copy the plane of AVFrame into a buffer :

  


    size_t rgb_size = av_image_get_buffer_size(AV_PIX_FMT_BGR24, bgrFrame->width, bgrFrame->height, 1);

    uint8_t *dst_data;
    dst_data = (uint8_t *)(av_malloc(rgb_size));

    av_image_copy_to_buffer(dst_data, rgb_size, (const uint8_t* const *)bgrFrame->data, bgrFrame->linesize, AV_PIX_FMT_BGR24, bgrFrame->width, bgrFrame->height, 1);



  


  If I try to save to file the BGR image is correctly copied :

  


  char filebuf[256];
snprintf(filebuf, sizeof filebuf, "%s%d%s", "out_", pPacket->dts, ".rgb");
std::FILE *output=fopen(filebuf,"wb+");  

fwrite(bgrFrame->data[0],(pFrame->width)*(pFrame->height)*3,1,output);  
std::fclose(output);


  


  So it looks like my copy to buffer function is faulty, but I can figure out what's wrong with it :

  


    uint8_t *dst_data;
    dst_data = (uint8_t *)(av_malloc(rgb_size));

    av_image_copy_to_buffer(dst_data, rgb_size, (const uint8_t* const *)bgrFrame->data, bgrFrame->linesize, AV_PIX_FMT_BGR24, bgrFrame->width, bgrFrame->height, 1);


  


• ffmpeg avformat_open_input always returns "Protocol not found" rv=(-1330794744)

  7 juin 2019, par bzivkovic

  Trying to get ffmpeg working in Visual Studio 2010. So far all ffmpeg headers and libs are loaded, no error or warning occurs.

  avcodec_register_all();
  
  AVFormatContext *pFormatCtx = NULL;
  
  char errbuf[256];
  
  pFormatCtx = avformat_alloc_context();
  
  int rv = avformat_open_input(&pFormatCtx, "myfile.ext", NULL, NULL);
  
  if (rv!=0){                              
  
      av_strerror(rv, errbuf, sizeof(errbuf));
  
  }

  The problem is, avformat_open_input always returning -1330794744 (errbuf="Protocol not found"). Tried x86 & x64 headers and libs on 32bit XP and 64bit W7. Whatever I put for "myfile.ext" (tried "file1.avi", "file=c :\file1.avi", "http://www.someweb.com/file1.avi", and even empty char* "") response is always "Protocol not found". Any ideas ?

• ffmpeg returns "method SETUP failed : 404 Not Found"

  1er juillet 2019, par Alex

  We’re using ffmpeg (build ffmpeg-20190628-098ab93-win32-static) to take a snapshot from camera RTSP streams on a Win 10 system. On some cameras, we’re getting this error :

  [rtsp @ 06813ac0] method SETUP failed: 404 Not Found
  
  rtsp://username:password@example.com: Server returned 404 Not Found

  Here’s an example command we use :

  ffmpeg -y -i rtsp://username:password@example.com -vframes 1 -pix_fmt yuvj420p 
  
    -vf select='eq(pict_type\,I)' -q:v 1 _test.jpg

  However, VLC can load the same stream (we can’t use VLC, though) from the same machine. Additionally, we’ve opened the firewall to ffmpeg (it popped up the two firewall dialogs and we allowed it through).

  We’ve found posts on the DESCRIBE error but nothing on SETUP. Any help is appreciated. Thank you.

  Update : In VLC, that RTSP stream asks for credentials twice for some reason. Wondering if that’s the cause.