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

Барт Гопник bart.gopnik at gmail.com
Sun Dec 29 08:42:00 CET 2013

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.

"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)?

> 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 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)?

As I know, there are differences in "MP3 Header"/"Xing tag"/"INFO
Tag"/"LAME Tag" and "delay"/"padding" terms in MP3! See detailed
explanation here: http://lame.sourceforge.net/tech-FAQ.txt

2013/12/28 Carl Eugen Hoyos <cehoyos at ag.or.at>

> James Darnley <james.darnley <at> gmail.com> writes:
> > > I don't know what --no-padding does
> > > but I suspect this is the default for FFmpeg
> > > (and cannot be undone).
> >
> > As I wrote it, so unless it has been changed,
> > ffmpeg (libavformat) will always write 8192 bytes
> > of padding to the header of flac files.
> Thank you for clarifying!
> Carl Eugen
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