[Music] Fw: [Audacity-devel] lossless vorbis editing]

[Alexandre Prokoudine]

----- Forwarded message from Joshua Haberman <joshua at reverberate.org> -----

From: Joshua Haberman <joshua at reverberate.org>
To: "audacity-devel at lists.sourceforge.net" <audacity-devel at lists.sourceforge.net>
Subject: [Audacity-devel] lossless vorbis editing
Date: Tue, 02 Dec 2003 00:54:32 -0800
Reply-To: audacity-devel at lists.sourceforge.net

As most of you know, I have been working this semester on modifying
Audacity to support lossless editing of Ogg Vorbis files.  I am happy to
announce that it is working in many cases, and that I have preliminary
code available to try.  You can download it from:

http://www.reverberate.org/audacity--thesiswork--1.3--patch-15.tar.gz

What works:
- When you import an Ogg, you will see green lines in the waveform
display indicating that those regions are known to come from Ogg files. 
Horizontal lines indicate the extent of the aliased regions.  Vertical
lines indicate the borders of the aliased regions.

- you can cut/copy/paste and all the region information should be
preserved.  There should continue to be a horizontal line throughout the
track.

- when you export as Ogg, Audacity will combine the original files into
a new file that is the result of your editing.

What doesn't work:
- the editing is not sample-accurate, and I'm not sure why.  The code as
it stands is creating Vorbis files as I expect it to, but the features
of the Ogg Vorbis format that let you cut on a particular sample are not
working as I expect.  See my unanswered question on the vorbis-dev list:
http://www.xiph.org/archives/vorbis-dev/200311/0051.html

To demonstrate this problem, import a Vorbis file, delete some data from
the beginning, export as ogg, then import the file you just exported
into the same project.  When you play the two tracks together they will
be slightly out of sync and you'll get a chorus-like effect.

- the Ogg exporter cannot (yet) export any data that *doesn't* come from
existing Ogg files (data that you didn't import as Ogg)

- ...lots more, I'm sure.

Try it if you like and let me know if you run into problems.

Josh


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----- End forwarded message -----

-- 
Alexandre Prokoudine		| "When you set yourself on fire and aim 
ALT Linux Documentation Team	|  for the sky, you hope to leave behind 
E-mail: avp at altlinux.ru		|  some sparks of heat and light"
JabberID: avp at altlinux.org	|                             Neil Peart
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