[MPlayer-dev-eng] a few nut suggestions [back-reference packets]

[Michael Niedermayer]

Hi

On Monday 04 October 2004 17:44, D Richard Felker III wrote:
> On Mon, Oct 04, 2004 at 01:48:18PM +0200, Michael Niedermayer wrote:
[...]

>
> > > > the back reference becomes pretty much unnecessary as searching
> > > > through 0.5 or so seconds of the bitstream is easy
> > >
> > > yes. but repeating data again and again could be very wasteful.
> > > especially if it's big data. (and who knows what someone will want to
> > > store in info packets...)
> >
> > yes, if we reverse the keyframe -> syncpoint index change u purposed we
> > could use the index to find this data very efficiently in non realtime
> > streams, and for realtime we must repeat the packets anyway due to packet
> > loss and similar
>
> how do you propose doing that, though? if we index every keyframe, the
> index will be huge since audio is typically all-keyframes! then nut
> will suck just like avi... :(

if we put a sync point between every packet it will also be huge, actually far 
huger but noone will do this, neither will anyone put every keyframe in the 
index


>
> i know you proposed the rule of only using startcodes & indexing a
> keyframe when it's the first keyframe to come after a non-keyframe,
> but this optimization just works based off the assumptions of current
> codecs. what if you had a codec (audio or video) with a pattern like
> IBIBIBI or IBBIBBIBBI? adding tons more startcodes and index entries
> would be a serious overhead burden.

what about the following rule: (1 index per stream and only keyframes in the 
index)
if the distance between 2 consecutive index entries is larger then 0.5 seconds 
then there may be no keyframe between them


[...]
> > > > furthermore the demuxer is able to find video keyframes, so why
> > > > shouldnt it also use the same method to find audio or subtitle
> > > > keyframes?
> > >
> > > there will be a sane upper bound on distance between keyframes. is
> > > there necessarily a sane upper bound on distance between subtitles or
> > > infopackets? imo not...
> >
> > imo there should be
>
> i meant a natural upper bound. whether we want to impose one is
> another matter.

there is no natural upper bound for video keyframes


[...]
-- 
Michael

"I do not agree with what you have to say, but I'll defend to the death your
right to say it." -- Voltaire