WavPack correction file (hybrid mode)

[Underground78]

As far as I can tell ffmpeg is currently not able to use WavePack correction file when decoding a WavePack track.

It would be great if this could be implemented.

Relevant excerpt from WavePack user documentation:

If the -c option is specified (in addition to the -b option), then WavPack will generate an additional file that will contain the information that was discarded to generate the lossy .wv file. This file will have the same name as the .wv file but will have the extension .wvc (the 'c' is for "correction"). When WvUnpack is used to restore the .wav file, it will attempt to find the .wvc file in the same directory as the .wv file. If it is found then the decompression will be lossless and will be reported as such, otherwise lossy decompression will be reported (assuming that any information was actually discarded during the original compression).

[Underground78]

Sample files: ​audio track + ​correction file wvc

[Carl Eugen Hoyos]

Replying to Underground78:

Relevant excerpt from WavePack user documentation:

Much more relevant would be what current FFmpeg says about it...

[Underground78]

Well relevant to understand what is a correction file obviously.

FFmpeg does not say much about it. I couldn't find anything relevant in the documentation. Opening the correction file fails which is probably expected in all cases anyway, the wv file is correctly decoded but the output makes no mention of the correction file and I don't think it says anything about the file being lossy or lossless.

I am not sure what info you need but please do tell.

[Carl Eugen Hoyos]

$ ffmpeg -i lossy.wv -i lossy.wvc -acodec pcm_s24le out.wav
ffmpeg version N-79254-g3749748 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      55. 20.100 / 55. 20.100
  libavcodec     57. 34.100 / 57. 34.100
  libavformat    57. 30.100 / 57. 30.100
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 40.102 /  6. 40.102
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, wv, from 'lossy.wv':
  Duration: 00:00:23.00, start: 0.000000, bitrate: 874 kb/s
    Stream #0:0: Audio: wavpack, 48000 Hz, stereo, s32p (24 bit)
[wavpack @ 0x34c65c0] No block with decorrelation terms
Input #1, wv, from 'lossy.wvc':
  Duration: 00:00:23.00, start: 0.000000, bitrate: 871 kb/s
    Stream #1:0: Audio: wavpack, 48000 Hz, stereo, s32p (24 bit)
Output #0, wav, to 'out.wav':
  Metadata:
    ISFT            : Lavf57.30.100
    Stream #0:0: Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s
    Metadata:
      encoder         : Lavc57.34.100 pcm_s24le
Stream mapping:
  Stream #0:0 -> #0:0 (wavpack (native) -> pcm_s24le (native))
Press [q] to stop, [?] for help
size=    6469kB time=00:00:23.00 bitrate=2304.0kbits/s speed= 265x
video:0kB audio:6469kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.001540%

[George Nistor]

only foobar 1.3.10 is able to correctly process the WavPack files in hybrid mode; add the files by adding the directory in the foobar's playlist;

that one uses the same ffmpeg for the WavPack decoder?

[Balling]

I would argue that -i -i mechanism is nuts. No, just the presense of the file should affect this.