[FFmpeg-user] How to set FLAC --no-padding equivalent switch in FFMPEG?

James Darnley james.darnley at gmail.com
Sun Dec 29 11:33:41 CET 2013

On 2013-12-29 08:42, Барт Гопник wrote:
> I know that FFMPEG doesn't use LibFLAC and has its own FLAC codec based on
> source code of Flake (http://flake-enc.sourceforge.net/). But it's a pain
> in the ass to find any info on Flake encoder options.

For specific options for flac you can see them by running:
ffmpeg -h encoder=flac

You can see other options for other components in a similar way.
-compression_level is a common option so it doesn't shiow under these
and then you have to guess what it might control or just read it from
the source.

> "equivalent options" = options produced equivalent (not bit-by-bit
> identical streams, but have comparable compress ratio) output.
> Maximum value of -compression_level option in LibFLAC is 8, maximum value
> of -compression_level option in Flake and FFMPEG is 12.
> Is FLAC files compressed by FFMPEG with -compression_level 12 compatible
> with reference FLAC decoders and hardware implimentation?
> Should I use -compression_level 8 instead of -compression_level 12 for
> saving compatibility (is -compression_level 8 in FFMPEG equivalent to
> -compression_level in LibFLAC in this regard)?

If I remember using flake correctly I think that using anything greater
than 8 (the max in libflac) produces what the flac project calls
"non-subset files".  The flac project gives lots of warning about these
files.  I don't know if they actually present any problems for hardware

12 doesn't compress much more than 8 so if you are worried about this
then stick with 8.

If you really want to know ask somewhere more dedicated than ffmpeg's
support list.  Perhaps try Hydrogenaudio.

>> It should be simple(ish) to add a control for the padding.  I can do it
> if people want it.
> It would be nice! Could you please add a control for the padding in FLAC
> (equivalent to --no-padding swith in LibFLAC)? ;)

I shall get my environment set up again

>> I have also considered padding for ID3 tags on mp3 files.
> Did you mean MP3 Header (http://gabriel.mp3-tech.org/mp3infotag.html)
> instead of leading padding (silence to the beginning of each song)?
> MP3 header is very useful thing. It must be enabled for VBR (VBR MP3 files
> without Xing tag are unusable) and should be (very recommended) for CBR MP3
> files. But I think users should still be able to control (enable/disable)
> MP3 header. Could you please add a control MP3 header (equivalent to -t
> swith in LAME)?

When I said ID3 I meant ID3, specifically ID3v2 and an equivalent of
lame's --pad-id3v2-size option.

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