[Matroska-devel] Re: Multi-Angle (summary) + Multi-resolution files

Steve Lhomme steve.lhomme at free.fr
Mon Sep 20 16:06:17 CEST 2004


Steve Lhomme a écrit :

> Virtual Track A : mixes Track 1 in 4:3 and partial Track 2 in 16:9
> Virtual Track B : mixes Track 3 in 4:3 and partial Track 4 in 16:9
> 
> Track A is Angle #1 <- default angle to play
> Track B is Angle #2
> 
> _definition of the matroska tracks_ :
> 
> <Tracks>
>   <!-- Track A -->
>   <TrackEntry>
>     <TrackNumber>1</TrackNumber>
>     <FlagDefault>1</FlagDefault>
>     <TrackGroup>1</TrackGroup> <- angle 1
>   </TrackEntry>
>   <TrackEntry>
>     <TrackNumber>2</TrackNumber>
>     <FlagDefault>1</FlagDefault>
>     <TrackGroup>1</TrackGroup> <- angle 1
>   </TrackEntry>
> 
>   <!-- Track B -->
>   <TrackEntry>
>     <TrackNumber>3</TrackNumber>
>     <FlagDefault>0</FlagDefault>
>     <TrackGroup>2</TrackGroup> <- angle 2
>   </TrackEntry>
>   <TrackEntry>
>     <TrackNumber>4</TrackNumber>
>     <FlagDefault>0</FlagDefault>
>     <TrackGroup>2</TrackGroup> <- angle 2
>     <TrackOverlay>1</TrackOverlay> <- the track number or the group 
> number ?
>   </TrackEntry>
> </Tracks>
> 
> There are a few pbs to solve here :
> - there are 2 default tracks
> - the TrackOverlay is not really useful when you already have the list 
> of tracks that form an angle. We might simply drop it, but it could also 
> be interresting to know if a track of a group can be played alone.
> - a track that can be played alone could be used in many angle groups

I've been thinking a bit more about this second problem. Actually some 
tracks depends more on the other in the same group. And some can be 
mutualy exclusive in the same group. So we need to clarify this...

The first thing is that a track should be usable with other alternative 
resolutions. That probably means belonging to different groups.

Let's consider the following tracks :
Track 1: ---------------------------------------------------
Track 2: ------------          -----------     -------------
Track 3:             ----------           -----
Track 4:       ----------------

You can play:
- Track 1 alone
- Track 1 with Track 2 where applies
- Track 1 with Track 3 where applies
- Track 1 with Track 4 & 2 where applies
- Track 1 with Track 4 & 3 where applies
- Track 1 with Track 4 & 2 & 3 where applies
- Track 2 with Track 3 where applies

You can't play:
- Track 2 alone
- Track 3 alone
- Track 4 alone
- Track 2 with Track 4
- Track 3 with Track 4

So we need to allow all the possibilities and not allow the impossible 
ones. I guess that's a common problem to solve in computer science, but 
I don't know any good answer (yet). But when we'll have solve it, we 
won't have any angle & resolution problem anymore :)



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