[foms] WebM Manifest
jeroen at longtailvideo.com
Thu Mar 17 13:10:46 PDT 2011
On Mar 17, 2011, at 1:47 PM, Philip Jägenstedt wrote:
>> Next, the Stream API needs to be very strictly defined in terms of how provided A/V frames should be formatted, and how and when codec initialization data must be (re)sent.
> I may very well be in need of education, but I don't see why that needs to be the case.
> Assume a manifest at its simplest is a list of URLs and switchover times. If one has a "manifest API" that allows one to add URLs and switchover times, then surely anything that can be done with a manifest can be done with the API? If a manifest solution doesn't require inspecting the data outside of the normal decoding, why would it be necessary when one uses an API?
When portraying a manifest as a "list of URLs" you are following an approach similar to Apple HLS, imposing two restrictions on your datamodel:
1. Interleaving. Only when audio + video are interleaved in fragments, you can have a list of URLs. Your presentation is basically chopped up vertically (time) instead of horizontally (stream). In any case where you have more than one quality level of a certain track, there is data duplication. Sometimes (5 video qualities with the same audio, like Apple HLS) that might be acceptable. Sometimes (5 video qualities with 5 audio languages) the amount of data simply explodes.
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