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• (C) avcodec_receive_frame (ffmpeg) function always returns AVERROR(EAGAIN)

  13 avril 2021, par Levyu

  I was following this tutorial : http://dranger.com/ffmpeg/tutorial01.html
and was trying to change some deprecated functions, and so I had to try to use the avcodec_send_packet and avcodec_receive_frame functions.

  


  The problem I'm having is that avcodec_receive_frame always returns AVERROR(EAGAIN).

  


  My decoding function is as follows :

  


  static int decode(AVCodecContext *pCodecCtx, AVFrame *pFrame, AVPacket *packet) {
    
    int ret = avcodec_send_packet(pCodecCtx, packet);
    if (ret<0) {
        fprintf(stderr, "error sending packet for decoding\n");
        exit(1);
    }

    while (ret>=0) {        
        // avcodec_receive_packet(pCodecCtx, NULL);
        ret = avcodec_receive_frame(pCodecCtx, pFrame);
        if (ret == AVERROR(EAGAIN)) {
            fprintf(stderr, "\naverror(eagain) ret = %d\n", ret);
            return -1;
        }
        else if (ret == AVERROR_EOF) {
            fprintf(stderr, "eof\n");
            return -100;
        }
        else if (ret <0) {
            fprintf(stderr, "error during decoding\n");
            exit(1);
        }
    }
    return 0;
}


  


  Everywhere I read said that this is solved by calling avcodec_send_packet with the next frame, but this does not solve the problem for me because this function is being called in a loop :

  


  
    while (av_read_frame(pFormatCtx, &packet)>=0) {
        // is this a packet from the video stream?
        if (packet.stream_index==videoStream) {

           frameNotFinished = decode(pCodecCtx, pFrame, &packet);

            // did we get a video frame?
            if (!frameNotFinished) fprintf(stderr, "it worked!");
        }
        av_packet_unref(&packet);   
    }


  


  I should probably also add that avcodec_send_packet always returns 0 (success).

  


  Any help would be much appreciated.

  


• pngdec : Stop trying to decode once inflate returns Z_STREAM_END

  28 septembre 2013, par Martin Storsjö

  pngdec : Stop trying to decode once inflate returns Z_STREAM_END
  If the input buffer contains more data after the deflate stream,
  
  the loop previously left running infinitely, with inflate returning
  
  Z_STREAM_END.
  Reported-by : Mateusz "j00ru" Jurczyk and Gynvael Coldwind
  
  CC : libav-stable@libav.org
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavcodec/pngdec.c

• ffmpeg : avcodec_open2 returns invalid argument

  12 mai 2016, par roari

  i’m reusing the sample code from the developer 64bit release of ffmpeg in my application to encode a video :

  AVCodec* pCodec_{nullptr};
  
  AVCodecContext* pContext_{nullptr};
  
  
  
  avcodec_register_all();
  
  pCodec_ = avcodec_find_encoder(AV_CODEC_ID_MPEG2VIDEO);
  
  if (!pCodec_) {}
  
  
  
  pContext_ = avcodec_alloc_context3(pCodec_);
  
  if (!pContext_) {}
  
  
  
  pContext_->bit_rate = 400000;
  
  pContext_->width = size.width();
  
  pContext_->height = size.height();
  
  
  
  pContext_->time_base.den = 1;
  
  pContext_->time_base.num = fps;
  
  
  
  pContext_->gop_size = 10;
  
  pContext_->max_b_frames = 1;
  
  pContext_->pix_fmt = AV_PIX_FMT_BGR0;
  
  
  
  if (codec_id == AV_CODEC_ID_H264) {
  
      av_opt_set(pContext_->priv_data, "preset", "slow", 0);
  
  }
  
  
  
  int err = avcodec_open2(pContext_, pCodec_, nullptr);
  
  if (err < 0) {}

  AVCodec* and AVCodecContext* look like they are allocated correctly. avcodec_open2 then returns invalid argument (-22).

  I use : Windows 10 64, VS2013 Compiler, Qt Creator IDE, ffmpeg(2016-05-12) 64bit.

  The sample i took the code from is "decoding_encoding.c".

  Any ideas ?