[ogg-dev] possible regression in libogg

Monty Montgomery monty at xiph.org
Wed Dec 4 02:51:40 PST 2013

Not at all... I should have done that myself.


On Wed, Dec 4, 2013 at 2:32 AM, Oleksij Rempel <linux at rempel-privat.de> wrote:
> Am 03.12.2013 23:49, schrieb Monty Montgomery:
>> Any time code is stuck in a loop calling ogg_sync_pageseek() or
>> ogg_sync_pageout(), you'll see most of the time sunk into checksum
>> calculation.  It's the only thing in libogg that _can_ take much time.
>>  This is not likely a libogg bug, but a bug in the code calling libogg
>> in a tight loop.
>> Looking at the file listed in the bug, there's a page discontinuity at
>> the very beginning; after the header packets/pages, there are several
>> missing pages before data starts normally.  Whatever generated or
>> trimmed this file did a ragged job at the beginning.
> This file was generated long time ago. Not sure for 100% but it was
> gstreamer + OggIndex. may be ffmpeg2theora.
>> This isn't an
>> error, strictly speaking, but it's not completely correct either.
>> First thing I'd check is whether or not this has tripped up the
>> seeking code in gstreamer...  Or actually, _any_ kind of analysis of
>> what gstreamer is actually doing.
> ok. If you do not mind  i'll repost you message in the bug.
>> A profiler is not a debugger!  It's just waving a dead chicken at this
>> problem, then trying to read the tea leaves.  As of yet we have no
>> concrete evidence of what is happening aside from gstreamer
>> calculating a ton of Ogg checksums.
>> Monty
> --
> Regards,
> Oleksij

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