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Support track media fragments for A/V in Presentation API?
Should we support track media fragments as well as timed fragments in annotations? W3C specs provides means to specify fragments but no formalization for discovery/naming:
- https://www.w3.org/TR/media-frags/#media-fragment-syntax
- https://www.w3.org/TR/media-frags/#fragment-dimensions
- https://www.w3.org/TR/2011/WD-media-frags-recipes-20111201/#rtsp-track
How would a client find out what tracks are called?
Could this be be solved with ranges instead of URI fragments? Annotating a named part could be a range.
2017-09-05 AV Call: Channel (left/right) use case discussed, but no way to determine what to put in the track parameter of a media fragment without explicit format level information. Defer until there's some real implementations/requirements.
See also use case for Annotating audio and video channels separately.
(This issue split out from #807.)
The media fragments spec is pretty vague, with examples of numerically-indexed tracks... (#track=1&track=2 to select "both tracks 1 and 2")
The HTML5 spec has a different example, using #track=Alternative to select a track labeled as "alternative". https://www.w3.org/TR/html5/embedded-content-0.html#selecting-specific-audio-and-video-tracks-declaratively Note that since audio and video tracks are indexed/numbered separately in HTML5 media, it's unclear what a numbered track would mean...
Would need to test to see what's actually supported across a broad subset of browsers...
Note that tracks can be selected at runtime in the player via the audioTracks and videoTracks properties: https://www.w3.org/TR/html5/embedded-content-0.html#audiotracklist-and-videotracklist-objects however that will not provide things like left/right channel selection.
Ok, supposedly the 'id' returned from the tracks is legit for usage of the media fragment, per spec... But nobody implements the track lists anyway except on MSE SourceBuffer. Nevermind. :P
Not going to support in presentation 3.0. Could be added as a minor release if there were later agreement to add support
I think that this is closed by the resolution of #1332? We can refer to the use-case justified "tracks" now with the new selectors. At the very least it should be use-cases-needed?
Can we? I think we can refer to audio or video, but not, say, "left-channel" or "french-audio".
Eds: Close won't fix. We should treat these resources as black boxes rather than trying to extract bits from them. No one has asked for this in the last 7 years, think we're probably okay.