[vorbis] Why the commotion about file extensions?

[Oscar Sundbom]

On Thu, 17 Jul 2003 15:04:44 +0300 (IDT)
Beni Cherniavsky <cben at techunix.technion.ac.il> wrote:

> Hauke Duden wrote on 2003-07-17:
> 
> > > Good point.  File extensions normally represent groups of related
> > > formats.  I don't propose differentiating everything (e.g. standalone
> > > FLAC from Ogg FLAC).  I do want as a minimum to tell apart these
> > > categories:
> > >
> > > - Lossy audio: Vorbis, Speex.  But speech is useful to distinguish
> > >   from music, so making Speex separate is not a bad idea.
> > > - Lossless audio: FLAC, WAV (not that we can change the later ;).
> > > - Video: Theora, Tarkin.
> >
> > Well, I think it is important not to make this extension stuff too
> > complicated. What would be the benefit of having different extensions for
> > lossy and non-lossy audio? Remember that if you think about individual files
> > you can always use a utility to see its properties (if you are an "above
> > average" user). IMHO the extension should provide just enough information to
> > differentiate between the two main categories of audio and video in order to
> > be able to handle large amounts of files. The way the codec can be included
> > as an optional part may also be something that could be defined. But as is
> > always the case in software design it is important to know where to stop.
> > Otherwise you end up encoding the whole audio header in the filename.
> >
> Lossy vs. lossless is very important.  If I have both I can only keep
> the lossless and always be able to recreate the lossy one but not vice
> versa.  Consider the frequent scenario: you encode a bunch of .wav
> files into `.ogg` files.  Then you listen and decide the quality is
> not high enough, so you delete the `.ogg` files and reencode them with
> higher quality.  Then you are satisfied and delete the `.wav` files to
> save space.  Imagine how confusing it would be if the `.wav` files
> would also have the same `.ogg` extension.  But FLAC is exactly like
> WAV in this rescpect, it's only a bit smaller.
 
Wouldn't just a more elaborate naming scheme (sans extension) on your part be a better choice for that?
For example "Artist - Songtitle [FLAC].ogg", or why not just ".flac.ogg". File naming can never be written
in stone anyways (well, it can, but you get my point), meaning that of course a person can choose the naming
most appropriate for that person's personal use. I think the thing most interesting here is some sort of
official recommendation on fundamental extensions for use with files with fundamentaly different properties.
Personally, I think video vs. audio (only) is a good separation. Sticking a codec name before the extension
won't change it, it'll just inform the more knowledgeable users of what it is, so calling it an extension is
dubious.

<p>> > > Right - but you are trying to imporve it for the user who has trouble
> > > remembering codecs, while harming me <wink>.  As a person who is going
> > > to use Xiph (or other open) formats as much as possible, I don't care
> > > for many formats average users do, and I can easily remember all Xiph
> > > codecs ;-).
> >
> > Wouldn't the scheme with the secondary optional codec extension work for you
> > as well?
> >
> Work - yes, as well - no ;-).  It's inconvenient and not supperted
> well enough on windows as already mentioned in this thread.
 
Hmm ... seems I already answered this ... kinda. I don't think, actually, I'm kind of sure that the optional codec extension is just shown by Windows (treated as part of the file name). As mentioned, I hardly think the
issue here is catering for every person's possible need but a more general "I-wanna-give-this-neato-file-to-my-friend" way.

Following here are some more ramblings on parts of this thread that I just haven't gotten around to answering before:

We don't need no steenking file extensions."
The claim that has come up a few times here that "this isn't '95" and "files are no longer identified by their extension by any software" is right, but oh so wrong. The
two statements are correct, but the point at which they're heading isn't. I can't imagine many pieces of
software that have ever identified files based on extension. File formats just doesn't work like that. They
usually have some identifier in them and contain header information etc. that need to be checked by the software. It's reading the file anyways, so why shouldn't it check for the validity of the file it's using.
Extensions are there for the user, not the software (other than displaying interesting files to the user).
  On a related note. Having the OS do file format checking (which then most probably has to be done all over by
the software again) before launching appropriate software could prove to be an even more malicious thing than
Windows hiding extensions per default. You'd double click on an .avi (for example), believing it was a movie and
instead launching a virus 'cause the OS decided it was an executable and didn't care the least what you wanted
to do with the file.

I also wonder: It's been claimed that Ogg audio files only contain one codec. Is this necessarily true, or just
a misconception of the OggVorbis format (which may make such claims). If it is true, why? If the Vorbis format
requires such limitations to the Ogg format ... why? and would it at all be possible to use several codecs in
the same file. Perhaps it's just a limitation to logical streams (of which there can be many in a file).

Finally I'd just like to agree with Hauke: What if the format gets very popular and people start using ogg
containers instead of avi (for example). That would create a whole array of codecs that can be used and have to
be mentioned in the extension (if such a recommendation is made) .flac_mjpeg_ogg someone?

Apologies if this all seems incoherent. It's late and a lot of gathered thoughts are fighting for room, though
none seem to have gotten what it deserves. :)

Regards
Oscar
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