[ogg-dev] ogg dirac granulepos in oggz tools

[David Flynn]

On 2008-11-23, Conrad Parker <conrad at metadecks.org> wrote:
> 2008/11/24 David Flynn <davidf+nntp at woaf.net>:
>> On a slightly unrelated note, i keep hitting the following error in
>> liboggz when using the oggz tools on an ogg dirac stream:
>>
>> /home/davidf/project/liboggz/src/liboggz/oggz.c:202: oggz_close:
>> Assertion `oggz_dlist_is_empty(oggz->packet_buffer)' failed.
> I expect that will be in the code that tries to calculate granulepos
> when it is not present on the page, which is actually unecessary for
> this mapping -- so I expect it will be straightforward to fix.
> Of course the file will be necessary to debug it :-)

Solved.  The ogg file in question had an EOS page with gp = UINT64_MAX
and liboggz stashes all packets away in the packet_buffer until a gp is
found.

Hacking the muxer i was using to set the eos page to have a timestamp of
0 solves it.  I'll now need to make it sample-and-hold for the eos page.

I do find that a bit ugly -- using a magic value in a timestamp to imply
that no packet ends[1] -- surely it is better to use the segment table?
There are times that a non dated packet is the easiest way to transmit
something and to let the decoder sort out the missing timestamp. Unless
i've missed the fact that it is being stashed to allow for timestamp
interpolation?

[1] yes, the rfc alludes to that.

..david