[vorbis] WinVC v0.91 released

[Grzegorz Adam Hankiewicz]

On Sun, Feb 10, 2002 at 12:46:24PM +0200, Beni Cherniavksy wrote:
> > >Multiple lines are in the spec, and should definately be allowed - but
> > >be warned that tools such as vorbiscomment will not deal appropriately with
> > >them...
> > >
> > I've managed to do it fine with VorbisComment.
> >
> That's strange, I'm pretty sure it can't be done :-)

I can prove you wrong. I sent this email some days ago, but looks like I
may not have sent it to the apropiate place, maybe vorbis-dev would have
been the correct place. In few words, bash allows entering multiline tags,
maybe dos with bash can do it too.


---
Date: Wed, 6 Feb 2002 13:27:56 +0100
To: giles at xiph.org
Subject: Undefined behaviour problems with implementation of vorbiscomment

Hi.

I am mailing you since you are listed as one of the
authors of vorbiscomment, a program which I got with the file
vorbis-tools-1.0rc3.tar.gz. I've found a little problem with the contents
of the comments added to a vorbis file (.ogg). The problem lies somehow
in undefined behaviour for multiline comments, which vorbiscomment seems
to handle differently in output and input.

When the option -c is used to feed a file as input, or just typing the
contents of the file through stdin, vorbiscomment refuses to accept
multiline values.  I wouldn't find this very restrictive since you can
emulate them adding the same tag again and again for every line. But
you can introduce multiline values at the commandline with the -t
option. Under linux/bash you only have to leave the quotes open, and
vorbiscomment will happily accept all the lines you give it once you
type the end quote.

Ok, now, the problem with this is that vorbiscomment is not reflexive,
meaning that if I list the contents of an .ogg file, which contains
multiline values, and save it to a file, this won't be accepted as input
by vorbiscomment, it will give an error like "bad comment:%s" for every
added line.

I wanted to write a wrapper around vorbiscomment (I know I should
directly talk to vedit.c, but I'm lazy so far) and this can cause
me problems.  Therefore I request that some documentation about
this issue is written in either the man page, or the online help at
http://www.xiph.org/ogg/vorbis/doc/v-comment.html in order to clear
this problem. BTW, the man page contains that url with a typo: the dash
is missing.

My suggestion for this is to let multifile values exist (the retun char
is just like any other utf-8 valid char, isn't it?), and add a better
parser with escape characters to vorbiscomment. It will make it more
complex, but handling \ at the end of a line as an escape character
with the meaning of "this value is multiline and continues" and \\
for a normal valid character, it could fix the problem.

Also, is there some guarantee that tags will come in a specific order? As
they were added? Alphabetically sorted? Do players/readers have to
respect the given order of a file or can they modify it? Could you add a
'show version and exit' option through -v switch?

-- 
 Grzegorz Adam Hankiewicz   gradha at terra.es   http://gradha.infierno.org/

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