Playback stops when transitioning between periods - no video segments being fetched.

[sobbe81]

Have you read the FAQ and checked for duplicate open issues?
Yes. There are some other multi period issues but not sure if it's the same. Potentially the same as #8795

If the problem is related to FairPlay, have you read the tutorial?
N/A

What version of Shaka Player are you using?
4.15.5

Can you reproduce the issue with our latest release version?
Yes. The problem in #8795 is not reproducible in 4.4.3 so we tested that one and we cannot reproduce our issue either with that one.

Can you reproduce the issue with the latest code from main?
Have not tried

Are you using the demo app or your own custom app?
custom

If custom app, can you reproduce the issue using our demo app?
DRM encrypted so I cannot test

What browser and OS are you using?
Chrome, Mac

For embedded devices (smart TVs, etc.), what model and firmware version are you using?
N/A

What are the manifest and license server URIs?
Send this separately

What configuration are you using? What is the output of player.getNonDefaultConfiguration()?

What did you do?
Play multiperiod VOD (DAI)

What did you expect to happen?
All periods should play.

What actually happened?
When transitioning between content and ad break, shaka stops downloading video segments and playback stops. Audio and text segments are being downloaded but not video. If we force the player not to use the highest quality it works.

From the logs we wee that the SegmentPrefetch for video jumps from 1660 which should be the last segment in content period to 1843.98368 which is the first segment in the next content period and skipping the entire ad break.

11:35:34.427 player.js:8465 SegmentPrefetch(video:66) reused prefetched init segment at time, mapSize 1
11:35:34.488 player.js:8465 SegmentPrefetch(video:66) reused prefetched segment at time: 1654.98928 mapSize 1
11:35:34.863 player.js:8465 SegmentPrefetch(text:12) pop and abort prefetched segment at time: 1655
11:35:34.864 player.js:8465 SegmentPrefetch(text:12) reused prefetched segment at time: 1661 mapSize 1
11:35:35.244 player.js:8465 SegmentPrefetch(audio:10) pop and abort prefetched segment at time: 1655.0053333333333
11:35:35.246 player.js:8465 SegmentPrefetch(audio:10) reused prefetched segment at time: 1661 mapSize 1
11:35:35.973 player.js:8465 SegmentPrefetch(video:66) pop and abort prefetched segment at time: 1654.98928
11:35:35.975 player.js:8465 SegmentPrefetch(video:66) reused prefetched segment at time: 1660.98928 mapSize 1
11:35:36.677 player.js:8465 SegmentPrefetch(video:66) pop and abort prefetched segment at time: 1660.98928
11:35:36.679 player.js:8465 SegmentPrefetch(video:66) reused prefetched segment at time: 1843.98368 mapSize 1
11:35:36.796 player.js:8465 SegmentPrefetch(audio:10) pop and abort prefetched segment at time: 1661
11:35:36.797 player.js:8465 SegmentPrefetch(audio:10) pop and abort prefetched init segment
11:35:36.798 player.js:8465 SegmentPrefetch(audio:10) reused prefetched init segment at time, mapSize 1
11:35:36.904 player.js:8465 SegmentPrefetch(text:12) pop and abort prefetched segment at time: 1661
11:35:36.905 player.js:8465 SegmentPrefetch(text:12) pop and abort prefetched init segment
11:35:36.906 player.js:8465 SegmentPrefetch(text:12) reused prefetched init segment at time, mapSize 1
11:35:36.928 player.js:8465 SegmentPrefetch(audio:10) reused prefetched segment at time: 1666.989 mapSize 1
11:35:36.965 player.js:8465 SegmentPrefetch(audio:10) pop and abort prefetched segment at time: 1666.989
11:35:36.966 player.js:8465 SegmentPrefetch(audio:10) pop and abort prefetched init segment
11:35:36.967 player.js:8465 SegmentPrefetch(audio:10) reused prefetched init segment at time, mapSize 1
11:35:37.048 player.js:8465 SegmentPrefetch(text:12) reused prefetched segment at time: 1666.989 mapSize 1

Are you planning to send a PR to fix it?
no

[avelad]

I saw you sent an email, but without a stream URL to test, we can't help you. If you'd like to create a PR and fix it yourself, we'd be happy to review it; otherwise, the issue will be closed within 7 days.

[sobbe81]

Hi,

I have provided stream urls now. We tested this in the shaka demo player but we were not able to reproduce the issue there.

We have tried to troubleshoot this and it seems like shaka interprets our ad periods and content periods separately; like two different subgroups. And when it enters a ad period it instead of fetching segments in that period tries to find the next content period which is far ahead. Could this be due to that the bitrate differs a bit between the ad periods and content periods? I do not see the same grouping of periods when running the shaka demo player.

here's our non default config.

{"drm":{"servers":{"com.widevine.alpha":"<license-url>"}},"manifest":{"dash":{"ignoreMinBufferTime":true}},"streaming":{"rebufferingGoal":2,"bufferingGoal":30},"abr":{"defaultBandwidthEstimate":10000000,"advanced":{"minTotalBytes":8000000}},"preferredAudioLanguage":"sv","cmcd":{"enabled":true,"sessionId":"8eb6dbca-3c57-4f05-8ab5-d1ea41b1c0ec"}}'

[sobbe81]

Hi,

We have done some troubleshooting and I think that the problem occurs because the bitrates in the ad periods differs to much from the bitrates in the content.

For example the two highest bitrate variants in the manifest.

Ads
V0: 5.5 mbit/s, avc1.640028
V1: 4.5 mbit/s, avc1.4d4028

Content
V0: 6.7 mbit/s, avc1.640028
V1: 4.8 mbit/s, avc1.4d4028

As a consequence the PeriodCombiner thinks that V0 in the ads best matches V1 in content and combines those. The problem is that the codec string differs between V0 and V1 and I guess that is what is causing the issue with that video segments are nog being downloaded and logs indicate subgroups of periods.

I would argue that finding a variant with the same codec string would be a priority compared to finding variant with the closest bitrates. shaka.util.PeriodCombiner.areAVStreamsExactMatch_ called from isVideoStreamBetterMatch_ tries do to this but does only use the normalized codec. Could this be changed to use the full string instead or in addition to?

I have sent manifest and license urls via email. Those urls expires after some time so if you would like to run them yourself. I still cannot reproduce the issue in the test player though.

I have tried to configure shaka with useStreamOnceInPeriodFlattening : true and with that I can no longer reproduce the issue with V0 and V1. Not sure if there are other issues with that work around though.

[avelad]

@tykus160 can you review it? Thanks!

[tykus160]

@sobbe81 please test with #8842
Unfortunately I couldn't test extensively your stream due to WV license issue, but I checked period combiner results and it looks better, as less variants are created.
Btw, profile check has one issue on your stream - for ads V4 uses avc1.42c01f and V5 uses avc1.42c01e, but for content both V4 and V5 use avc1.42c01e.

[sobbe81]

Hi @tykus160

That seems to fix our issues! Is it possible to include this in 4.14 and/or 4.15 bug fix releases?