presentationTimeOffset value not honored by players or am I using the presentationTimeOffset attribute wrong ?

[poornimaprakashmj]

I have an requirement of inserting ad mid roll and I'm trying to insert an ad after 20 seconds. So I have the 3rd period where in segment starts at startNumber 11 , as each segment duration is 2 secs. I have a problem here as I see a jump in the seek line of player by 20 seconds and losing last 20 seconds of media at the end. I'm attaching the mpd. Can anyone tell me what is the mistake here. I'm using dash.js player version 4.2.1.(get this message in console :[42812][GapController] Jumping gap occuring in period 1 starting at 40 and ending at 60.015146. Jumping by: 20.244896000000004 ). Attaching the mpd. Attaching it has a txt . I can zip and upload segment files as well if necessary,
presentation.mpd.txt

[dsilhavy]

At first glance there are multiple errors in the MPD:

• presentationTimeOffset needs to be specified in timescaleunits. For Period with id=2 this means 20* timescale.
• You set the startnumber to 11 but the first segment in your timeline is specified with t=0. The @t parameter is equal to the earliestPresentationTime of your first segment in the period (segment 11)
• In the end your ' @presentationTimeOffsetshould be the same value as the@t` in your SegmentTimeline

[poornimaprakashmj]

Hi with the suggestions provided I made the changes and uploading the new MPD here. Can you review it once ? Since my audio adaptation set had @t parameter in every segmentTimeLine object, I retained it only in the first one and removed the @t attributes from other segmentTime objects. Is this correct to do ? The MPD I'm attaching now plays well in dash.js player but doesn't play on the chrome extension downloaded to play hls and dash videos(https://chrome.google.com/webstore/detail/native-mpeg-dash-%20-hls-pl/cjfbmleiaobegagekpmlhmaadepdeedn?hl=en).
timescale2.mpd.txt

[dsilhavy]

For Period 2 try setting the first audio entry to
<S t="794624" d="88064" r="5">

The 20 seconds do not align with the boundaries of the audio segment. Thats why you need to cut them off with the period boundaries and @presentationTimeOffset`

[poornimaprakashmj]

hi I tried what was suggested and this caused mismatch in audio and video sync . Also the first audio entry without any modification was like without any r attribute(S t="0" d="89088"). Are you sure we have to repeat the first audio entry 5 times and also change the d attribute to 88064 instead of 89088 .And can I know how did we end up on value of 794624 for timestamp ? I'm asking these because I'm doing this split in the code and have to come up with a generic logic to do this. I have to deal with various mpds where on the fly I have to do mid ad insertion based on afterNumberOfSeconds (say 20seconds or 40seconds)as input. I'm attaching the mpd files what all I tried.
segmentAudioTest1.mpd.txt
segmentAudioTest2.mpd.txt