Support for MPD Anchors

[ivivona]

Hi! I'm trying to play a live stream not from the live edge (now) but from the manifest first segment (ex: start from the beginning of a live concert). I read the specification and such issue can be solved using the MPD Anchors, specifying a t parameter.
I'll tried using the shaka demo player (latest version) and it doesn't seem to be working (it always start form the live edge). Is it supported? Or should I try using the player API instead?

Thanks in advance.

[vaage]

@ivivona Could you provide more information? Is this in your app and you just looking for a way to start from the start of the video regardless of it being live? Or are you trying to prepare content for use in someone else's app and need a way to signal to them that they should start at the start and not the live edge?

[ivivona]

@vaage i control both the generation and the player, so any solution is ok, but I think it will be better to let the player know from where to reproduce using the info in the MPD (in this case the url anchor). The use case is: a "watch from the start" button in page A goes to the player in page B with certain manifest URL, the player's page is kind of generic because the the manifest could be a VOD or a live.

[vaage]

@ivivona When you load a manifest (shaka.media.player.load), there is an optional parameter you can set called opt_startTime. If you set that to 0, does it solve your problem? That would be the simplest way to ensure that the player always starts playing the content from the start.

[ivivona]

@vaage thanks for the response. I understand that there is a javascript solution, but my question was if shaka implements/supports MPD Anchors as indicated in the DASH specification.

[joeyparrish]

Shaka Player does not support MPD anchors, but we do have other solutions to that problem. As @vaage pointed out, you can specify a start time when you call load(). For your case (starting a live stream at time zero), that seems like the best solution.

For more complex scenarios, you can configure a payable range. See #246 for the discussion that led to that feature, and the playRangeStart and playRangeEnd fields of https://shaka-player-demo.appspot.com/docs/api/shakaExtern.html#PlayerConfiguration for the API.

Does that help answer your question?

[vaage]

@ivivona Was @joeyparrish able to answer your question? If so, feel free to close the issue.

[ivivona]

Yes, thanks. Anyway, should this be implement in the future?

[joeyparrish]

We don't have any plans to support MPD anchors at this time. We believe that specifying start times and play ranges is a more general solution that applies across manifest types.