[ogg-dev] oggz-validate does not seem to check for correctly framed headers
conrad at metadecks.org
Mon Nov 10 17:06:12 PST 2008
2008/11/11 Ivo Emanuel Gonçalves <justivo at gmail.com>:
> While testing the new vcut, some of the early results had badly framed
> headers. I actually didn't notice it at first, because I was testing
> with oggz-validate, but ogginfo does identify the problem:
> "WARNING: Vorbis stream X does not have headers correctly framed.
> Terminal header page contains additional packets or has non-zero
> Conrad (or someone else) may want to change the tool to identify these
> files. There's a sample attached.
good idea, and thanks for also supplying an example file!
How did we get here? Originally oggz-validate just checked the basics
of Ogg framing, which are independent of the codec. These are the
things that liboggz's oggz_write() will enforce - things like BOS and
EOS placement, and that granulepos is non-decreasing. Later we started
adding checks for codec-specific constraints, like that Theora BOS
must come before the Vorbis BOS. Perhaps there are more codec-specific
constraints we can check for.
liboggz already knows how many headers each track should have, so it
should be fairly straightforward to add a check for this that works
for all codecs (assuming that the constraint -- that header and
non-header packets must not share a page -- applies to all Ogg media
More information about the ogg-dev