[M4IF Technotes] Object questions

[Rob Koenen]

> Just to be absolutely sure I have understood. Does the 
> maximum of 32 objects
> in a scene include things like sound? This implies that a 
> video encoded
> using simple profile, level 0 could not have any audio .

Good question.
Max. number of objects was in this case for the Visual Profile   Level
Audio profiles   levels have their own maximum. Same applies to Graphics 
PRofiles, which delimited the elements such as graphics, text etc.
In the case of Graphics profiles, there are other complecity measures
than the number of objects. 
> Just out of interest, how is stereo sound treated? Is it one or two
> 'objects'?

You can have a 5.1 channel object. The Audio level definition may actually
restict the number of channels. (Some audio levels are very advanced, 
and allow you to have, say, one very complex object or 32 very easy ones.
You are free to allocate your resources in these level definitions.)
> I realise this but was wondering whether there were any 
> practical pointers.

There is a slew of literature on object segmentation. Just try
something like "object segmentation mpeg-4" in Google.
> Re: BIFS. I thought that was best for synthetic images 
> whereby the meshes
> are being transmitted. 

No. BIFS is a scene description language used to (yes, 
you guessed it) describe the scene. You can even used it
to describe the layout of 2 video objects (and it can
get simpler still). BIFS also contains commands to animat the
scene. BEfore going deeper into this discussion, I recommend
that you read 
http://mpeg.telecomitalialab.com/standards/mpeg-4/mpeg-4.htm
> I can only imagine doing this with an I-VOP as a P-VOP would 
> be relative to
> the previous frame. If the previous object was a duck and the 
> new one a cow,
> then there's not a lot of similarity. A goose on the otherhand...

I was actually merging the duck in the background.
Morphing a duck into a cow is an interesting other issue.
Rob