[vorbis] using vcut on split ogg files

[Carsten Haese]

On Thu, 2003-07-31 at 13:59, Marc Heckmann wrote:
> On Thu, Jul 31, 2003 at 01:39:24PM -0400, Carsten Haese wrote:
> > On Thu, 2003-07-31 at 13:10, Tyler Knott wrote:
> > > Marc Heckmann wrote:
> > > >the problem is the following, because the oggfiles are split, they lack
> > > >a proper header and have become unuseable. 
> > > >
> > > >for example, t1059667200.ogg is an oggfile for one 30 minute segment:
> > > >
> > > >[mh at signal tmp]$ oggdec t1059667200.ogg
> > > >OggDec 1.0
> > > >ERROR: Failed to open input as vorbis
> > > >
> > > Try using a hex editor to add the headers from another ogg vobis file to 
> > > the corrupt ones?
> > 
> > That's not going to work for various reasons. 
> 
> can you elaborate?

When you split an Ogg Vorbis stream at a random point, the following
happens:
* The first half ends unexpectedly without the end-of-stream flag, and
it ends with a truncated vorbis packet.
* The second half begins with a corrupted vorbis packet, is header-less,
and doesn't have any Ogg framing at the beginning.

Tacking the headers from the first half onto the second half will help a
bit, but there's still going to be junk at the beginning of the second
half. In the best case a player will skip the junk and you lose part of
your stream, and in the worst case it might not play at all. 

-Carsten

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