+ ffmpeg -y -i sample.wav -c:a flac -compression_level 12 -f flac sample.flac
ffmpeg version 3.4.4 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.4.0 (Alpine 6.4.0)
  configuration: --prefix=/usr --enable-avresample --enable-avfilter --enable-gnutls --enable-gpl --enable-libass --enable-libmp3lame --enable-librtmp --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libx264 --enable-libx265 --enable-libtheora --enable-libv4l2 --enable-postproc --enable-pic --enable-pthreads --enable-shared --enable-libxcb --disable-stripping --disable-static --enable-vaapi --enable-vdpau --enable-libopus --disable-debug
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'sample.wav':
  Duration: 00:02:06.63, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> flac (native))
Press [q] to stop, [?] for help
Output #0, flac, to 'sample.flac':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Audio: flac, 44100 Hz, stereo, s16, 128 kb/s
    Metadata:
      encoder         : Lavc57.107.100 flac
size=    8706kB time=00:02:06.62 bitrate= 563.2kbits/s speed=15.8x    
video:0kB audio:8698kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.093057%


+ ffmpeg -y -i sample.flac -f s16le -
ffmpeg version 3.4.4 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.4.0 (Alpine 6.4.0)
  configuration: --prefix=/usr --enable-avresample --enable-avfilter --enable-gnutls --enable-gpl --enable-libass --enable-libmp3lame --enable-librtmp --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libx264 --enable-libx265 --enable-libtheora --enable-libv4l2 --enable-postproc --enable-pic --enable-pthreads --enable-shared --enable-libxcb --disable-stripping --disable-static --enable-vaapi --enable-vdpau --enable-libopus --disable-debug
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, flac, from 'sample.flac':
  Metadata:
    ENCODER         : Lavf57.83.100
  Duration: 00:02:06.63, start: 0.000000, bitrate: 563 kb/s
    Stream #0:0: Audio: flac, 44100 Hz, stereo, s16
Stream mapping:
  Stream #0:0 -> #0:0 (flac (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, s16le, to 'pipe:':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
    Metadata:
      encoder         : Lavc57.107.100 pcm_s16le
[NULL @ 0x7f45ee8c8600] sample/frame number mismatch in adjacent frames
size=   21564kB time=00:02:05.17 bitrate=1411.2kbits/s speed= 240x    
video:0kB audio:21564kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%


+ ffmpeg -y -i sample.wav -f s16le -
ffmpeg version 3.4.4 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.4.0 (Alpine 6.4.0)
  configuration: --prefix=/usr --enable-avresample --enable-avfilter --enable-gnutls --enable-gpl --enable-libass --enable-libmp3lame --enable-librtmp --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libx264 --enable-libx265 --enable-libtheora --enable-libv4l2 --enable-postproc --enable-pic --enable-pthreads --enable-shared --enable-libxcb --disable-stripping --disable-static --enable-vaapi --enable-vdpau --enable-libopus --disable-debug
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'sample.wav':
  Duration: 00:02:06.63, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, s16le, to 'pipe:':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
    Metadata:
      encoder         : Lavc57.107.100 pcm_s16le
size=   21813kB time=00:02:06.62 bitrate=1411.2kbits/s speed= 899x    
video:0kB audio:21813kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%


+ cmp sample.wav.pcm sample.flac.pcm
cmp: EOF on sample.flac.pcm after byte 22081536, in line 205105


+ echo decode failed, bug reproduced
decode failed, bug reproduced