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

[Ben Boeckel]

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...
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
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