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• Xuggler - Getting snapshots from RTMP stream

  12 avril 2014, par Yev

  I'm using the last xuggler lib on Java 7 (MacOs Maverix).
  I need to get a

  png snapshot from a live rtmp stream served by wowza.

  For this I'm using the default com.xuggle.xuggler.demos.DecodeAndCaptureFrames.
  There are some problems :

  1. reader.readPacket() has a delay of 5 minutes (it seems xuggler tries to buffer or guess the format, difficult to explain)
  2. After this delay, some external process starts (I guess it's ffmpeg) and my CPU usage is 100%.

  3. In parallel with high CPU load, I see the png files created correctly, but after 2-3 minutes I get always the following exception

     14:40:35.785 [main] ERROR org.ffmpeg - WriteN, RTMP send error 32 (14 bytes)
     14:40:35.790 [main] ERROR org.ffmpeg - WriteN, RTMP send error 32 (42 bytes)

  Any idea ?

• dts to m4a (aac) encoding - qaac, neroaacenc encoder output issues

  9 avril 2014, par user8979

  greets

  I want to encode a dts 5.1 audio source to m4a (aac) 5.1 with same playback duration.
  Intend to use either qaac or neroAacEnc.

  The output is the same per encoder with .mkv and .dts extracted from .mkv as input audio source.
  .mkv source piped to encoder using ffmpeg
  .dts source piped to encoder using ffmpeg and wavi with .avs input, .avs using NicAudio avisynth plugin, to decode .dts source for separate encodes to confirm if challenges encountered were from ffmpeg or elsewhere (both produced the same issues so concluded the issues originated from the respective encoders)

  • qaac output is same duration as .mkv
    issues : mediainfo reports output is 2ch while mediatab and ffmpeg report output is 5.1ch (lfe)

    mediainfo :

    Channel(s) : 2 channels
    Channel(s)_Original : 6 channels
    Channel positions : Front : L C R, Side : L R, LFE
    this channel position and channel combination is not possible, so which is it ?

    ffmpeg (5.1 info bold) :

    Stream #0:0(und) : Audio : aac, 5.1, fltp

    mediatab :

    Channel(s) : 6 channels
    ChannelPositions : Front : L C R, Side : L R, LFE

  • neroaacenc output has same channels, 5.1
    issue : ffmpeg reports output is longer than mkv audio track by 0.06 seconds (60 ms) and it begins after 0.054677 seconds (54.667 ms)

    Chapter #0.0 : start 0.054667

  Questions :

  1. qaac output
     
     • is the output stream 2ch or 5.1ch ?
     • if it is 2ch, what qaac option(s) leave the channels in output same as input AND report the correct channels ?
     • if the output is 5.1ch, does this mean every qaac output keeps the input channels (without using —chanmap or other such options) ? if so then its easy to ignore mediainfo channel information for qaac encodes.
       
       • why did mediainfo report 2ch ? could the stream report incorrect channels to a media player (implies incorrect playback) ? is there any way to get rid of the misleading channel information shown in mediainfo ? (expecting the information to be stored in the file, that is where would like to get rid of it)
  2. neroaacenc output
     • how can one ensure neroaacenc output is exact same duration as input ?
     • if not possible to change the output duration, does that mean when muxing audio with video, include the 54.667 ms delay to maintain sync ? (audio delay of -0.054667 s in this case) ?

  Commandlines were many so not included. Let me know if they would be helpful.

• Extract audio and video frames from a video [on hold]

  27 avril 2014, par zeitgeist

  I tried to extract video frames using Aforge FFMPEG. But it is quite slow and extracts video quailty is low. Also it doesn’t support audio functionality. So I need a library that would be extracting its audio and quality video frames.

  Below code is extracted video frames.

          VideoFileReader reader = new VideoFileReader();
  
          VideoFileWriter writer = new VideoFileWriter();
  
          reader.Open(@"D:\Ali\Videos\katy.mp4");
  
          writer.Open( @"D:\Ali\Videos\katy_.mp4", reader.Width, reader.Height, reader.FrameRate, VideoCodec.MPEG4 );
  
          Bitmap videoFrame;
  
          while((videoFrame = reader.ReadVideoFrame()) !=null )
  
          {
  
              writer.WriteVideoFrame(videoFrame);
  
              // dispose the frame when it is no longer required
  
              videoFrame.Dispose();
  
          }