[MPlayer-dev-eng] nut seeking without an index

[Michael Niedermayer]

Hi

On Thu, Sep 08, 2005 at 03:27:14AM -0400, Rich Felker wrote:
> On Wed, Sep 07, 2005 at 06:21:56PM -0400, Rich Felker wrote:
> > > * updating the timetamps in the syncpoints to match the farthest rightward
> > > keyframe of any stream require seekig back (i think this one wasnt proposed)
> > 
> > Could you explain this better? It sounds like it might be very good,
> > but I don't really understand what you mean.
> 
> Oh, somehow I missed the "require seekig back" (sic) part. >_<
> Anyway I don't see how this could help now... I was misreading it I
> think and thought the "require seekig back" was referring to streams
> in which you'd have to seek way back to find a keyframe... Or maybe it
> still is and now I'm misreading it? I can't make any sense of it..

it has the same problem as the single back pointer suggestion, so its not 
too usefull


> 
> > > maybe richs idea with backward pointers at sync points can be amended a
> > > little to solve the issue:
> > > store a single pointer at every syncpoint which points back to a point so 
> > > that every stream has at least 1 keyframe between the point and the current
> > > sync point
> > 
> > This could be one hugeass useless backward pointer in the presence of
> > subtitles. I know one anime movie (Tenshi no Tamago) with only about
> > 10 lines of dialogue over 2 hours...
> 
> Unfortunately I can't come up with anything reasonable except either
> having a backward pointer for each stream, or treating subtitle and
> info streams separately and excluding them from the backpointer rules.
> However I think the latter choice is bad, since it may be desirable to
> seek according to an info stream, especially if the info stream
> represents song/chapter/etc boundaries.

i still think the single pointer is enough, a file which stores keyframes
once every 2 hours, can only be seeked to at 2hour granularity and yes
you can by knowing that there are no non-keyframes in between skip
over it in principle but you dont know that, not even with an index
i rather think that we should do something about large gaps
then find some hackisch way to support it


[...]
> Personally I'd still be interested in seeing if there's any way we can
> do a sane distributed index....

if we can drop the 1pass sequential writing requirement then this shouldnt
be difficult, otherwise its complicated and fragile

[...]

-- 
Michael