[FFmpeg-devel] [PATCHv2] flac: ignore IDv3 tags if vorbis tags exist

Michael Niedermayer michaelni at gmx.at
Tue Feb 3 05:13:49 CET 2015


On Tue, Feb 03, 2015 at 01:36:13AM +0000, Ben Boeckel wrote:
> On Tue, 03 Feb, 2015 at 00:40:46 GMT, Reimar Döffinger wrote:
> > Yes, and?
> > Point one: ID3 won, it is generally supported. Insisting on something
> > else IMHO is just being a pain on the user for little reason and
> > nothing we should strive to emulate.
> > Point two: If despite that warning a ID3 tag exists, it seems sensible
> > to assume it does so for a good reason and shouldn't be ignored. If it
> > contains wrong information it should be removed, and that is
> > relatively easy to do. I suspect removing FLAC tags isn't as easy in
> > case things are broken the other way round.
> > I don't really care much, but ignoring an ID3 tag to me seems like the
> > solution with much lower usability.
> 
> They're ignored only if vorbis tags exist. The problem is that they are
> likely to be largely duplicated and you hit the code where the vorbis
> parser will group values of tags with the save name together, so you end
> up with:
> 
>     Title: Foo;Foo
> 
> I could blacklist tags this doesn't make sense for (probably just
> integer ones, and title), but that's hacky. Dedup is also a possibility,
> but since IDv3 isn't really meant to be in flac files to begin with...

isnt the id3 + vorbis tag issue the same as if the user would seek
back to the begin and read metadata afterwards ?


> Anyways, at least one user has hit this:
> 
>     https://trac.ffmpeg.org/ticket/3799
> 
> Looking at it, the encoder is claimed to be flac.exe and seems to be the
> reference code (at least the options look valid), so I can only imagine

your patch drops the encoder id metadata, which seems to
also have contained the encoding parameters, is this intended ?


> the tags were added by EAC (running the same thing here doesn't produce
> IDv3 tags at least). Similar code might be needed for ogg decoding as
> well.
> 
> --Ben
> 
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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are best at talking, realize last or never when they are wrong.
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