Parameters to enforce a specific buffer level?

[aelgendy97]

What are the parameters I can change to make sure the buffer level doesn't exceed a specific threshold. I checked the Settings.js file and changed both the stableBufferTime and bufferTimeAtTopQuality (my video isn't considered a long form) to the threshold I want; however, I keep seeing the buffer levels exceeding that threshold. I am using a 4s segment and my MPD is passing the conformance check.

Any pointer would be appreciated

[dsilhavy]

You are right, the description in Settings.js is confusing. You are using the right settings. The logic is currently as follow:

1. The ScheduleController checks for the buffer target. As an example, in the nightly build bufferTimeDefault (previously called stableBufferTime in v4) is set to 18 seconds.
2. It then compares the current buffer level to the buffer target. If bufferLevel < bufferTarget then _shouldBuffer returns true.
3. The next request is executed

That means you probably see the buffer target being exceeded by a maximum equal to your segment duration. I think it would be cleaner to take the segment duration into account and check:

bufferLevel + segmentDuration < bufferTarget.

I will take this question/discussion to our dash.js call next week.

[aelgendy97]

Thanks @dsilhavy. This is helpful

[dsilhavy]

@aelgendy97 I just merged a PR to address this issue in #4594 . The changes should be visible in the nigthly branch soon: https://reference.dashif.org/dash.js/nightly/samples/dash-if-reference-player/index.html