Wiki requirements and implementation alternatives update

Hi,

I've updated the wiki with my ideas for requirements [1] and two implementation approaches [2] described for MPEG-2 media resources. One  approach is the same approach as [3] - exposes in-band track metadata as a separate TextTrack. The other approach, which was suggested by Cyril, makes each tracks metadata available in an attribute of that track.

Regards,
Bob

[1] http://www.w3.org/community/inbandtracks/wiki/Main_Page#Requirements
[2] http://www.w3.org/community/inbandtracks/wiki/Main_Page#Implementation_Alternatives
[3]http://www.cablelabs.com/specifications/CL-SP-HTML5-MAP-I02-120510.pdf