[Delta] Codec negotiation

[Justin Karneges]

On Thursday 06 November 2008 16:35:09 Pau Garcia i Quiles wrote:
> 1. Take the resolutions Alice supports (A1, A2, A3) and the
> resolutions Bob supports (B1, B2)
>
> 2. Calculate a very simple "cross-correlation" between each pair of
> resolutions: A1 and B1, A1 and B2, A2 and B1, A2 and B2, and so on.
> The "cross-correlation" algorithm could be as simple as the percentual
> deviation:
>
>   0.5 * ( B1_x / A1_x + B1_y / A1_y ) = 0.5 * 1.742 = 0.871
>   0.5 * ( B2_x / A1_x + B2_y / A1_y ) = 0.5 * 3.484 = 1.742
>   0.5 * ( B3_x / A1_x + B3_y / A1_y ) = 0.5 * 6.969 = 3.485
>   0.5 * ( B1_x / A2_x + B1_y / A2_y ) = 0.5 * 0.87 = 0.43
>   0.5 * ( B2_x / A2_x + B2_y / A2_y ) = 0.5 * 1.742 = 0.871
>   0.5 * ( B3_x / A2_x + B3_y / A2_y ) = 0.5 * 3.532 = 1.766
>
> 3. Take the value closer to 1, i. e. the resolutions which are closer
> in size.

Yes, this is an interesting approach. :)

> In this case, both 160x120 for Alice and 176x144 for Bob, and 
> 320x240 for Alice and 352x288 for Bob would be equally preferred and
> deciding between those two would be a case of "I prefer a bigger
> camera window" or "I prefer a smaller camera window".

I'm not quite sure what you mean here.  By "deciding between those two" do you 
mean deciding between the two "sets" { 160x120, 176x144 } and { 320x240, 
352x288 } ?

Also, are you suggesting that "320x240 for Alice and 352x288 for Bob" should 
mean both parties operate at different, but similar, resolutions?  Since 
Alice did not offer 352x288, it is an unusable mode I think.  At least, this 
is the case in Jingle.

-Justin