[vorbis] Debian mp3->vorbis transcoding

[Stan Seibert]

On Wed, 2002-08-28 at 11:49, Craig Dickson wrote:
> debian-devel list this morning. Another Debian developer is proposing to
> submit an mp3->vorbis transcoding program for inclusion in Debian. I
> have objected to this on the grounds that the resulting vorbis files
> will sound like crap, and I have also pointed out that the vorbis
> developers have a low opinion of this sort of transcoding (I think this
> is an accurate representation of the developers' views -- if not, I
> apologise for the mistake). I also observed that if such transcoding is
> really necessary, it's as trivial as decoding the mp3 to .wav and then
> vorbis-coding the .wav, therefore a dedicated program isn't really
> worthwhile.

(Disclaimer: I'm not a Debian developer.)

You are correct that generally developers and "power-Vorbis" users have
a generally low opinion of transcoding.  We discourage such activity
because transcoding:

* Lowers the quality slightly of the resulting file.  (Assuming a
comparable quality setting is used on the Ogg file.)
* Does not show off the improved quality Vorbis provides.
* Produces files that, if they were to be released into general
distribution via file trading networks, would not accurately reflect the
excellent quality/bitrate ratio achievable with Vorbis.  ("These Vorbis
files sound like my MP3s!")

Many users do not realize these things, assuming that lossy coding works
like the Zip and friends.  So part of the transcoding objection is just
an excuse to perform "user education."

However, if one really understands the above caveats, I personally don't
see why transcoding should be so taboo.  I can see two useful cases:

* Compatibility with hardware/software -- This is more likely a reason
to transcode from Ogg to MP3 and not the other way around.

* Ethical reasons -- Some people may not wish to use decoders of dubious
legal standing.  I imagine this is the reason that Debian would be
concerned about MP3s.

As another poster already pointed out in this thread, a transcoder would
have the same licensing issues that a decoder would have, so Debian
would gain no additional "purity" by including one.  Assuming that issue
can be worked around, I would personally like to see a transcoder that
both warns users of the problems with transcoding AND automatically
marks the output files as transcoded so they can be readily identified.

Are there any suggestions for a "unofficial standard" transcoding
marker?  Perhaps just a Vorbis comment:

TRANSCODED=Freeform string describing previous encoding

Example:

TRANSCODED=192kbps MP3


---
Stan Seibert

<p><p>--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.