[vorbis-dev] Xiph Magic

[Tom Hargreaves]

J C Fitzgerald wrote:
>
> On Thu, Jul 17, 2003 at 10:35:12AM +0300, Beni Cherniavsky wrote:
> >
> > There is already a detailed Vorbis entry, distributed with the latest
> > file(1) versions.
> >
> Oh, okay. My system's a little older.
> >
> > I just wonder what is "Native Vorbis" and "Native Speex"?
> > It seems that you are detecting standalone Vorbis/Speex packets with
> > no wrapper whatsoever.
> >
> Correct.
> >
> > The problem is that such a thing is
> > undecodable - you need some way to mark the packet boundaries. So no
> > such beasts exist.
> >
> That would be why I had to synthesis the test data for these. Perhaps
> "Feral", "Pathological" or "Liberated" would be better adjectives than
> "Native", then. :-)
> 
I've seen what you call "native" vorbis files in the wild. Try running
"mplayer -dumpaudio" on an ogg sometime...

(Yes, I did wonder about their decodability; I tried and failed to
find an easy way to decode them, although it should be possible for
non-peeled files AFAIK.)

Nonetheless, it might be potentially useful to be able to recognise
such raw files, as they might be produced by accident (e.g. as
mplayer does above).

Tom.

PS. During the course of my experiments I came up with the following
one-liner for stripping the Ogg layer (and I can confirm that it
produces valid FLAC files from ogg-flacs):

perl -0777lpe'BEGIN{$/="OggS"}s/.{22}(.)//s,s/.{@{[ord$1]}}//s'
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