zapping and quick switching

[gwendalsimon]

What should we put in catalog to enable tracks with I-frames

[ac-freeman]

My comment on #109 could be used in the case that it's a track of just I-frames, even if they're not at the full frame rate. If there's a separate P-frame Track, we would need to signal a dependency somehow. The renderGroup and altGroup fields don't cover this case. We could add a "frameType" of sorts, which would indicate the intended frame type (e.g., 0 = intra, 1 = inter, 2 = both). Then, a duo of complementary Tracks could be indexed by the combination of altGroup, resolution, codec, bitrate, and frameType.

[suhasHere]

Address the issue on using sub-group instead.