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• Problems converting .flv to mp3 using FFmpeg SDK

  13 mai 2013, par feadur

  I'm using the FFmpeg SDK to programmatically convert videos to mp3.

  I read the audio frames of the video this way :

  while(av_read_frame(pFromCtx, &pkt) >= 0) 
  
  {
  
      if(pkt.stream_index == audioStreamIndex) 
  
      {        
  
          avcodec_get_frame_defaults(frame);
  
          got_frame = 0;              
  
          ret = avcodec_decode_audio4(pCodecCtx, frame, &got_frame, &pkt);                
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Error decoding audio frame.\n");            
  
              continue;
  
          }
  
  
  
          if(got_frame) 
  
          {                    
  
            // Write the decoded audio frame           
  
            write_audio_frame(pToCtx, pToCtx->streams[pToCtx->nb_streams-1], frame);                    
  
          }                        
  
      }
  
      av_free_packet(&pkt);     
  
  }

  Decoding the audio from the input video file works fine. The problem occurs when I try to encode a mp3 frame :

  static void write_audio_frame(AVFormatContext *oc, AVStream *st, AVFrame *frame)
  
  {
  
    AVCodecContext *enc = st->codec;
  
    AVPacket pkt;
  
    int got_packet = 0; 
  
    int ret = 0; 
  
    av_init_packet(&pkt);
  
    pkt.data = NULL; 
  
    pkt.size = 0; 
  
  
  
    ret = avcodec_encode_audio2(enc, &pkt, frame, &got_packet);
  
  
  
    if (ret < 0) {
  
        // PROBLEM    
  
        fprintf(stderr, "Error encoding audio frame. \n");
  
        exit(1);
  
    }     
  
  }

  I get the following console output :

  [libmp3lame] inadequate AVFrame plane padding

  The only happens with .flv files, the code works fine for .mp4 files. Any clue what the error message means ?

  Thanks

• ffmpeg Video concat demuxer txt path

  19 avril 2013, par Steven Mills

  I'm making use of the ffmpeg command line process, specifically the demuxer (see here).

  I'm attempting to run the equivelent of this :

  ffmpeg -f concat -i C:\Users\Username\AppData\Local\mylist.txt -c copy output.avi

  I've tried it and it works fine in the console, however I can't figure out a way to get this to work through code. I've checked the path is right, I've checked the txt file is named correctly etc.

  ffmpeg.StartInfo.Arguments = "-f concat -y -i " + @"C:\Users\Username\AppData\Local\Temp\mylist.txt" + " -c copy output.avi";
  
  ffmpeg.StartInfo.FileName = "ffmpeg.exe";

  For the path I've tried with/without the @ before the path, I've tried \ and / instead of \, I've tried using System.IO.Path methods, but none of it seems to work. It always returns an error saying "file not found", and through debugging I can see that ffmpeg.StartInfo.Arguments always ends up having \ between folders, so I'm guessing that might be the issue.

  Does anyone have a clue how I'd go about circumventing this particular issue ?

• FFmpeg large input frames

  2 juillet 2015, par user3310761

  I have a problem that I cannot solve and I would really appriciate your help.

  I have large rgb24 frame (1M each) which i would like to stream to ffmpeg and convert them to mpegts h264 stream.

  Now, I know which arguments I need to supply to ffmpeg so the conversion will success, but I don’t have a clue how can I stream/provide the frames to ffmpeg since they are too large for udp and I can’t using files. ( It’s a demonstrate of a real time streaming).

  Thank for all the helpers It’s really important for me !