сurrentTime is significantly behind the start and end values in TimeRange

[levelness]

Hello,

When playing my livestream manifest in dashjs and shakaplayer, I encountered a problem where the player correctly downloads the chunks, but the stream does not start playing. After debugging dashjs, I observed strange behavior where currentTime is significantly behind the start and end of the timerange, causing the buffer not to fill and preventing the video from playing (according to my assumption).

This same stream plays normally on the Bitmovin player. Could you please suggest in which direction I can research to get the dashjs player to play the live stream? Perhaps there is a parameter I am unaware of or something else. Thank you!

[dsilhavy]

The timing in your manifest or your media segments might be wrong.

The media players calculate the segment to download based on the timing information provided in the MPD. Afterwards the media segment data is appended to the Mediasource buffer. The position of the media segments in the buffer is determined by the baseMediaDecodeTime in the segments taking potential compositionOffsets into account. For the media player the only way to influence the position of the segments in the buffer is to define a timestampOffset.

It sounds like the timing in your media segments does not match the timing signaled in the manifest. As a consequence, the segments are not placed at the right time in the buffer. Bitmovin might have a workaround in place for this.

[levelness]

@dsilhavy Thank you for your response, that is absolutely correct because, in my solution, a new manifest is generated on the backend from an ongoing live stream, and we want to play this new manifest.

Could you please clarify if I understand correctly that at the moment, I can't resolve this issue by adding some additional properties to the manifest, and the only solution is to patch the dash.js player to make it work with this case?

[dsilhavy]

You can try changing the @presentationTimeOffset in the manifest. The position of a media segment in the buffer is caluculated like this:

1. MediaSource@timestampOffset = Period@start - @presentationTimeOffset
2. Position in the media buffer = Segment@baseMediaDecodeTime + MediaSource@timestampOffset

[levelness]

Here is how my manifest looks right now https://gist.github.com/levelness/6f4527aee1d255cb6f4e0a464cc588f7

Should I try to add @presentationTimeOffset to every SegmentTemplate in it?

[dsilhavy]

You can try this, but you will need to take Period@start, MPD@availabilityStartTime and SegmentTemplate@startNumber into account. I suggest you check also the player logs (dash.js and Shaka) if there is any useful information about why the stream is not starting. The MPD@type also makes a difference, this is currently dynamic. Not sure if you want to create a static MPD instead