[MPlayer-dev-eng] Lots of stuff for NUT

[Rich Felker]

On Sat, Dec 31, 2005 at 04:32:49AM +0100, Michael Niedermayer wrote:
> Hi
> 
> On Fri, Dec 30, 2005 at 10:23:55PM +0200, Oded Shimon wrote:
> [...]
> > > > 7. real back ptr is back ptr / (10 + number of streams)
> > > > 
> > > > The smallest amount of space a syncpoint can take:
> > > > 
> > > > <8 byte startcode> <1 byte pts> <1 byte per back ptr> <1 byte frame code>
> > > > 
> > > > That's (10+number of streams), back ptr can divide by that, it actually 
> > > > does make the index about 1kb smaller or so...
> > > 
> > > Saving 1k out of 80k is rather pointless, and this is rather ugly.
> > > It's nice to keep multiplication and division to a minimum anyway for
> > > small implementations (even tho I know it's already needed for
> > > timebase).
> > 
> > Ok, whatever. /8 is pretty in regards to >>3 anyway. :)
> 
> why exactly dont you remove more LSBs? for example if the back ptr only
> specifies the position in 16k units you would have to search 16k in worst
> case, this isnt much ...
> so a single byte back_ptr could cover 16k*128= 2mb instead of 1k

I considered this once before but there seemed to be a problem. I
can't remember what it was though. :(

> > > > 8. syncpoints too big?
> > >   [...]
> > > > Rich had the idea of "stream group" which makes a group of streams be 
> > > > treated effectively as one for all back ptr purposes. Not so good...
> > > 
> > > Yes I hate this idea...
> 
> what about delta backpointer lists, so that a syncpoint can reference another
> syncpoint and only store the different back pointers, this other syncpoint
> obviously must not reference anything but contain a complete list ...

This will require several seek operations on the media in order to
complete the seeking, which is quite negative.. Consider slow media.

Rich