[vorbis-dev] thoughts about MP3 -> OGG convertor

[Linus Walleij]

On Tue, 18 Dec 2001, John Zitterkopf wrote:

> Why is this a bad IDEA? I take it it's because of the "lossy" nature of
> both types.

Its a bad idea because mp3-compression and vorbis compression affect the
audio in different ways: artifacts from the mp3compression will be mixed
with artifacts from the vorbis compression.

Or to put it simple: mp3 throws away information from your signal. You
then reconstruct it, and you have a signal with the same timespan but less
information about the original sound. Then vorbis throws away more
information during its compression stage, but at different "places".

Its like taping something from a tape that is already taped from something
else. Or taking a photocopy of a photocopy.

Cliffhanger: I PRESUME it could be possible to convert the kind of
mathematical information stored in MP3 files to the kind of
mathematical information stored inside vorbis files, without
decompressing the audio and recompressing it inbetween, thus creating a
minimal loss transfer method. If you love maths, transforms and the
like, by all means have a look at it.

Linus

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