[FFmpeg-trac] #4421(avcodec:new): flac md5 error with LPC precision 15

[FFmpeg]

#4421: flac md5 error with LPC precision 15
--------------------------------------+---------------------------------
               Reporter:  cehoyos     |                  Owner:
                   Type:  defect      |                 Status:  new
               Priority:  normal      |              Component:  avcodec
                Version:  git-master  |               Keywords:  flac
             Blocked By:              |               Blocking:
Reproduced by developer:  0           |  Analyzed by developer:  0
--------------------------------------+---------------------------------
 http://thread.gmane.org/gmane.comp.video.ffmpeg.user/56347
 A user uploaded a wav file that can be converted to flac but the flac cli
 reports a md5 error if the default lpc precision 15 was chosen and the
 output file is not bit-identical to the input file. FFmpeg allows to
 decode the flac file losslessly.
 {{{
 $ ffmpeg -i testwav_cut.wav out.flac
 ffmpeg version N-71222-gd858c3a Copyright (c) 2000-2015 the FFmpeg
 developers
   built with gcc 4.7 (SUSE Linux)
   configuration: --enable-gpl
   libavutil      54. 22.100 / 54. 22.100
   libavcodec     56. 33.100 / 56. 33.100
   libavformat    56. 28.100 / 56. 28.100
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 13.101 /  5. 13.101
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  1.100 /  1.  1.100
   libpostproc    53.  3.100 / 53.  3.100
 Guessed Channel Layout for  Input Stream #0.0 : stereo
 Input #0, wav, from 'testwav_cut.wav':
   Metadata:
     encoder         : Lavf56.28.100
   Duration: 00:00:10.00, bitrate: 1411 kb/s
     Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 2
 channels, s16, 1411 kb/s
 Output #0, flac, to 'out.flac':
   Metadata:
     encoder         : Lavf56.28.100
     Stream #0:0: Audio: flac, 44100 Hz, stereo, s16, 128 kb/s
     Metadata:
       encoder         : Lavc56.33.100 flac
 Stream mapping:
   Stream #0:0 -> #0:0 (pcm_s16le (native) -> flac (native))
 Press [q] to stop, [?] for help
 size=    1114kB time=00:00:10.00 bitrate= 913.0kbits/s
 video:0kB audio:1106kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 0.731545%
 }}}
 {{{
 $ flac -t out.flac

 flac 1.3.1, Copyright (C) 2000-2009  Josh Coalson, 2011-2014  Xiph.Org
 Foundation
 flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you
 are
 welcome to redistribute it under certain conditions.  Type `flac' for
 details.

 out.flac: ERROR, MD5 signature mismatch
 }}}
 Works fine with {{{-lpc_coeff_precision 14}}}.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4421>
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