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• Android : How to convert WAV/PCM to another audio format without MediaCodec API

  3 octobre 2013, par khelkun

  I've searched around the web and stackoverflow during a long time about this subject. I know it has been discussed many times but I'm looking for a friendly opinion on my use case.

  I have a vocal dictation application which uses android.media.AudioRecord. It allows me to edit the recorded raw PCM buffer : insert a new record inside it, delete a certain period in the record, append a new record at the end. The result is a WAV file, but it's a bit too big file for my needs, so I want to convert it to smaller file format.

  android.media.MediaCodec could have been the solution, but it requires API level 16 which is a too high restriction in my situation.

  It sounds to me that I only have 2 options :

  1. Use the NDK and an android portage of ffmpeg like the guardian project android-ffmpeg-java. But this solution sounds a bit too hard for me so far.

  2. Recording with android.media.MediaRecorder to output an audio 3GPP file encoded with the AMR_NB encoder. Then I'll have to understand this 3GPP file header and the AMR_NB format in details to be able to perform the audio editing operations on my record.

  I must also add that creating a zip file of the WAV file is not a valid option for me.

  Does someone know another option please ? And is option 2. actually possible to achieve ?

  Thanks for your time !

• Reading RTMP streams using FFMPEG returns AVERROR_EOF randomly

  9 octobre 2013, par user2628781

  I am using FFMpeg to receive RTMP streams. This logic is placed in a custom video player I am building.

  I managed to successfully connect to the RTMP stream and display the video correctly. However, after a period in time, the stream terminates prematurely with an AVERROR_EOF when I perform av_read_frame().

  This indicates to me that the file has ended so my demux, video and audio threads terminates thinking that the video has ended.
  However, the video playback hasn't yet reached its end (in the case of a file streamed through rtmp) or from a live stream (which runs forever). The EOFs are received very randomly so it may run for say 7 min before this occurs or after 3 mins.

  Is this a characteristic behaviour of RTMP or am I doing something incorrectly ?
  I am also having a similar problem with Http Live Streams using FFMpeg.

  A small snippet of the code is provided below :

   AVPacket packet;
  
  //start timeout timer and timeout
  
  __interrupt_timer.start();
  
  
  
  int ret = av_read_frame(format_context, &packet); //0: ok, <0: error/end
  
  
  
  
  
  //invalidate the timer
  
  __interrupt_timer.invalidate();
  
  
  
  if (ret != 0) {
  
      if (ret == AVERROR_EOF) { //end of file. FIXME: why no eof if replaying by seek(0)?            
  
          if (!eof) {
  
              eof = true;
  
              started_ = false;
  
              pkt->data = QByteArray(); //flush
  
              pkt->markEnd();
  
              qDebug("End of file. %s %d", __FUNCTION__, __LINE__);
  
              emit finished();
  
              return true;
  
          }
  
          pkt->data = QByteArray(); //flush
  
          //return true;
  
          return false; //frames after eof are eof frames
  
      } else if (ret == AVERROR_INVALIDDATA) {
  
          qWarning("AVERROR_INVALIDDATA");
  
      } else if (ret == AVERROR(EAGAIN)) {
  
          return true;
  
      }
  
      qWarning("[AVDemuxer] error: %s", av_err2str(ret));
  
      return false;
  
  }

• sidxindex : Remove parsing that isn’t necessary any longer

  28 novembre 2014, par Martin Storsjö

  sidxindex : Remove parsing that isn’t necessary any longer
  When we don’t adjust the Period start time, we don’t need to
  
  parse the earliest_presentation_time from the sidx boxes either.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] tools/sidxindex.c