title: aac-eld decoding in Linux
body: <p>I was in Vietnam and tried to learn Vietnamese.</p>
  
  <p>The difficult thing is to learn the pronunciation and I made an Android App to record voices. Vietnamese people are very nice and I collected more than 500 sound files.</p>
  
  <p>Now I'm trying to make a language learning app. To do that I try to reduce noise and normalize volume.</p>
  
  <p>I have chosen the following settings:</p>
  
  <pre><code>this.recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
  this.recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC_ELD);
  this.recorder.setAudioEncodingBitRate(96000);
  this.recorder.setAudioSamplingRate(44100);
  </code></pre>
  
  <p>(cordova AudioPlayer.java - default settings are crap)</p>
  
  <p>Now I have a problem. I'm not able to open the files with Audacity or FFmpeg.</p>
  
  <pre><code>./ffmpeg -i /tmp/speaker__ualp__x%E1%BA%A5u.mp4 /tmp/uu.wav
  ffmpeg version 1.1.2 Copyright (c) 2000-2013 the FFmpeg developers
    built on Feb 20 2013 10:50:54 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
    configuration: --enable-libfdk-aac
    libavutil      52. 13.100 / 52. 13.100
    libavcodec     54. 86.100 / 54. 86.100
    libavformat    54. 59.106 / 54. 59.106
    libavdevice    54.  3.102 / 54.  3.102
    libavfilter     3. 32.100 /  3. 32.100
    libswscale      2.  1.103 /  2.  1.103
    libswresample   0. 17.102 /  0. 17.102
  [aac @ 0xaada980] Audio object type 39 is not supported.
      Last message repeated 1 times
  Guessed Channel Layout for  Input Stream #0.0 : mono
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/speaker__ualp__x%E1%BA%A5u.mp4':
    Metadata:
      major_brand     : isom
      minor_version   : 0
      compatible_brands: isom3gp4
      creation_time   : 2013-01-29 15:53:11
    Duration: 00:00:01.21, start: 0.000000, bitrate: 116 kb/s
      Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 96 kb/s
      Metadata:
        creation_time   : 2013-01-29 15:53:11
        handler_name    : SoundHandle
  [aac @ 0xaada980] Audio object type 39 is not supported.
  Output #0, wav, to '/tmp/uu.wav':
    Metadata:
      major_brand     : isom
      minor_version   : 0
      compatible_brands: isom3gp4
      Stream #0:0(eng): Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
      Metadata:
        creation_time   : 2013-01-29 15:53:11
        handler_name    : SoundHandle
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (aac -&gt; pcm_s16le)
  Error while opening decoder for input stream #0:0
  </code></pre>
  
  <p>What can I do?</p>