[FFmpeg-devel] [RFC] better ogg seeking, keyframes only

Diego Biurrun diego
Sun Jul 6 14:57:47 CEST 2008


On Sun, Jul 06, 2008 at 01:37:53PM +0100, M?ns Rullg?rd wrote:
> Diego Biurrun <diego at biurrun.de> writes:
> 
> > On Thu, Jun 26, 2008 at 12:35:45PM +0200, Michael Niedermayer wrote:
> >> On Sun, Mar 23, 2008 at 04:37:05PM +0100, Diego Biurrun wrote:
> >> > On Wed, Mar 19, 2008 at 01:16:16PM +0100, Reimar D?ffinger wrote:
> >> > > I admit this is a rather ugly patch, but it improves things a lot, so
> >> > > maybe you can have a look and get it committable.
> >> > > There are several issues with seeking: for audio, PKT_FLAG_KEY is never
> >> > > set, so the patch ignores it there, the data_offset set by the code in
> >> > > util.c is wrong, so this code overrides it, and the most annoying
> >> > > thing: a keyframe most likely is split over multiple ogg pages, so
> >> > > this code just returns the start of the last page read by the last
> >> > > get_packet as start offset for the keyframe - this means we might
> >> > > actually end up a few frames before the key frame (in theory up to 255),
> >> > > if the encoded frames are very small.
> >> > 
> >> > Hmm, I still get artifacts when seeking in Theora video, for example
> >> > with the samples from mphq...
> >> 
> >> I can confirm this, it doesnt work here either
> >
> > So who knows how to fix this? :)
> 
> I do.  Can you please look up the home addresses of the Xiph devs,
> while I fetch the shotgun?

Sure.  But do you also have a code fix? :)

Diego




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