Re: [MMUSIC] New Version Notification for draft-abhishek-mmusic-superimposition-grouping-00.txt(Internet mail)

[Paul Kyzivat <[e-mail]>]

Rohit,

I had another thought. See below.

On 1/19/21 12:16 PM, Paul Kyzivat wrote:
> Rohit,
> 
> On 1/19/21 2:57 AM, rabhishek(RohitAbhishek) wrote:

[snip]

>> *Rohit: The ordering mechanism will be needed. Suppose we have a 
>> background X with transparency=100, and a superimposed media A with 
>> transparency=50. A over X would mean that X would visible partially 
>> through A, however X over A would mean that A wouldn't show through X.*
> 
> If the ordering is needed, then you need to specify how it is 
> determined. IMO it is permissible to use the order of values in the 
> a=group: line to specify this ordering. (RFC5888 doesn't ascribe any 
> semantics to this ordering of values, but neither does it forbid 
> assigning meaning for particular grouping semantics.) I am not certain 
> if Christer agrees with me on this point. The alternative is to use a 
> new attribute in the grouped media descriptions for this purpose.)

Perhaps a clean way to do this would be to replace the "transparency" 
attribute with one that specifies both the transparency and the order. E.g.,

    a=superposition:transparency=80,layer=3

	Thanks,
	Paul