[DASH] Possible improvement to detecting end of live events

[juechemparathy]

Any pointers to Exoplayer support for detecting when a DASH Live stream has finished.Thanks.

[tonihei]

If the stream is actually finished, I'd assume that you receive an onPlayerStateChanged event with the playback state Player.STATE_ENDED. That depends on the manifest however. Do you have an example for a manifest with an ended live stream?

[juechemparathy]

@tonihei - Here is the test url - https://content.downlynk.com/channel/29e9c85c070f413fb71a3b2a39eed208.mpd?xtest=end30&prettydash=1
I don't see the playback state as Player.STATE_ENDED on end.

[juechemparathy]

@tonihei @ojw28
There are really 2 things to pay attention in the manifest -

The lack of a minimumUpdatePeriod on a dynamic manifest, and the addition of MPD presentation duration.
so when you see those things the live event has been finalized at a final length. The addition of the presentation duration is the final length and the removal of the minUpdatePeriod signals that no further manifest queries are necessary.

Please suggest if this doesn't make sense or there is some other standard way of handling this.Thanks.

[ojw28]

I think you should be turning type="dynamic" to type="static" when the manifest stops updating.

[tonihei]

Yes, that is what I was looking for. We only use the type tag to determine whether we should expect further dynamic updates (and not end the playback) or whether the playback can be safely ended. Please change this tag if possible.

[juechemparathy]

Thanks @ojw28 @tonihei for the quick response. Having type=static for the last mpd triggered Player.STATE_ENDED correctly.

Any suggestions on detecting live streaming in this case. Currently we use boolean isLive = player.isCurrentWindowDynamic() || player.getDuration() == C.TIME_UNSET to dectect if its live streaming.Thanks.

[tonihei]

It's probably better just to check for player.isCurrentWindowDynamic(). When playing progressive streams (like Mp4 etc.) you'll always get a unset duration in the beginning until it becomes known - and you wouldn't want to classify such a case as live stream.

For the ended live stream case, it's slightly unclear how they differ from non-live streams from a player point of view. Both have a non-changing manifest. If your live streams usually only have a part of the period available, you could check for a non-zero offset in timeline.getWindow(0, new Window()).positionInFirstPeriodUs. But that depends on the type of content.

[peddisri]

I think I found one issue. I have one URL where the way a presentation ends is by signalling inband via emsg box in fmp4 . I see that the player is detecting the end of presentation, but is trying to either retry, or after max retry is over, throw a DashManifestStaleException.
https://github.com/google/ExoPlayer/blob/release-v2/library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java#L682-L689

IMO, if dynamicMediaPresentationEnded is true, there is no need to retry, and instead it should take the player to ENDED state. So this check needs to be re-looked.

https://github.com/google/ExoPlayer/blob/release-v2/library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java#L665

[ojw28]

If the presentation end has been signalled in-band, then shouldn't any attempt to request the manifest result in a static manifest being received? In which case you'd never hit the code paths you reference. It sounds more likely that the server is not updating the manifest to be static, which I think it should do.

[peddisri]

I don't think so. I'm trying to find if the spec mentions that explicitly or not. My high level understanding from the spec is that, a static MPD is primarily used for for a VIdeo-on-Demand, whereas Dynamic MPD is used for Live streaming, which can end, but not necessarily be streamed as VOD later. I've sent the sample content URL to the email id.

Section 4.5.2.1 says
"the event duration expresses the remaining duration of Media Presentation from the event time. If the event duration is 0, Media Presentation ends at the event time. If 0xFFFF, the media presentation duration is unknown. In the case in which both presentation_time_delta and event_duration are zero, then the Media Presentation is ended."

[ojw28]

Are you removing @minimumUpdatePeriod and finalizing the duration, as described by @juechemparathy further up? I can see the argument for that being sufficient to transition to the ended state (although given you're having to update the manifest to do this, it feels like it's easy to also change it to static).

It's definitely not sufficient to only signal with an in-band message IMO. Reopening primarily to consider the @minimumUpdatePeriod + finalized duration case.