Dash reference player not playing live segments

[sam89g]

Hi Team,

We are trying to understand the DASH-IF client behaviour for our ABR related development. We have some questions related the playback behaviour.

Sample MPD config:

MPD:
type="dynamic"
availabilityStartTime="1970-01-01T00:00:00.000Z"
publishTime="2021-12-22T10:14:12.670Z"
minimumUpdatePeriod="PT2.00S"
minBufferTime="PT10.00S"
timeShiftBufferDepth="PT300.00S"
suggestedPresentationDelay="PT10.00S"
maxSegmentDuration="PT3.00S"

Period:
id="2021-12-21T12:46:36.658Z"
start="PT1640090796.658S"

SegmentTemplate:

           timescale="90000"
           presentationTimeOffset="147608171699220"
           availabilityTimeOffset="0"
           duration="540000"
           startNumber="92868642"

Manifest Type: Non-segment timeline (Numbered)

As per calculation to retrieve the segment number for playback.

Segment Number = startNumber + (( Now – (availabilityStartTime + Period@start )) / Segment duration).
Segment Number = 92868642 + ((2021-12-22T10:14:12.670 – (1970-01-01T00:00:00.000 + 1640090796.658)) / 2 )
Segment Number = 92868642 + 19314
Segment Number = 92887956

As we know suggestedPresentationDelay value impacts the live segment number.

Segment Number = 92887956 – (suggestedPresentationDelay / Segment duration)
Segment Number = 92887956 – (10/2)
Segment Number = 92887956 – 5 = 92887951 ----> Segment number expected to be requested by the player.

But during our experiments the player is further going back by 15 segments and requesting for playback (92887936). We do not understand why player is adding additional 15 segments delay requesting the segments.

Please find the attachment for the sample MPD file.
kindly clarify, appreciate your support.

channel3.mpd.txt

Thanks,
Samson G

[dsilhavy]

At a first glance your calculation looks fine expect for the segment duration. According to your SegmentTemplate it is 540000/90000 = 6 and not 2 (value used in your calculation)

Is it possible to share the hosted version of your MPD? Or provide a BaseURL to be added to your example file? Also did you check if your application is maybe overwriting the default live delay values?

[sam89g]

Hi Dsilhavy,

Thanks for the time.

As the dash streams are hosted locally cannot provide the URL, Please see the attached MPD from live.

Thanks,
Samson G

channel3.txt