title: audio sample format s16p, ffmpeg or audio codec bug?
body: <p>I have a video file and I had dumped the video info to a txt file with ffmpeg nearly 3 year ago. </p>
  
  <pre><code>...
  Stream #0:1[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16, 256 kb/s
  Stream #0:2[0x1c1]: Audio: mp2, 48000 Hz, stereo, s16, 256 kb/s
  </code></pre>
  
  <p>But I found the format changed when I used the update ffprobe (ffprobe version N-78046-g46f67f4 Copyright (c) 2007-2016 the FFmpeg developers).</p>
  
  <pre><code>...
  Stream #0:1[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16p, 256 kb/s
  Stream #0:2[0x1c1]: Audio: mp2, 48000 Hz, stereo, s16p, 256 kb/s
  </code></pre>
  
  <p>With the same video, its sample format changes to s16p.</p>
  
  <p>I implemented a simple video player which uses ffmpeg. It can play video 3 years ago, but failed to output the correct pcm stream after changing to update ffmpeg. I spent lots time and finally found that the audio should have been s16 instead of s16p. The decoded audio stream works after I added the line before calling avcodec_decode_audio4,</p>
  
  <pre><code>audio_codec_ctx-&gt;sample_fmt = AV_SAMPLE_FMT_S16
  </code></pre>
  
  <p>but it is just a hack. Does anyone encounter this issue? How to make ffmpeg work correctly? Any hint is appreciated. Thanks!</p>