ffmpeg.c:504: error: Uninitialized Value
  The value read from best was never initialized.

ffmpeg.c:504:9: 
502.             av_log(st->codec, AV_LOG_WARNING, "Requested sampling rate unsupported using closest supported (%d)\n", best);
503.         }
504.         st->codec->sample_rate= best;
             ^
505.     }
506. }
