QoE Metrics Reporting - Support for BufferLevel metric

[dsilhavy]

Feature description

Buffer level status events should be exposed by the ExoPlayerAdapter class and included in the QoE metrics report.

Relevant specifications and corresponding clauses

• ISO/IEC 23009-1 5th edition - clause D.4.5
• 3GPP TS 26.501 Rel-17
• 3GPP TS 26.512 Rel-17
• 3GPP TS 26.247 - clauses 10.6.2 and 10.6.3

Example

<QoeMetric>
  <BufferLevel>
     <BufferLevelEntry t="2011-02-16T09:08:19" level="84673"/>
     <BufferLevelEntry t="2011-02-16T09:08:20" level="93874"/>
  </BufferLevel> 
</QoeMetric>

[dsilhavy]

Follow up question: Should the buffer level be derived once the metrics are requested or at a certain interval. For the latter, we can then return a list of all the collected bufferlevel entries since the last request.

[rjb1000]

Follow up question: Should the buffer level be derived once the metrics are requested or at a certain interval. For the latter, we can then return a list of all the collected bufferlevel entries since the last request.

ServiceAccessInformation.clientMetricsReportingConfigurations[] specifies the reporting interval for QoE metrics, but not the metric sampling interval. I conclude therefore that the sampling interval is implementation-dependent as of TS 26.512 V17.5.0.

I envisage two asynchronous activities:

• Media Stream Handler samples each metric at (currently implementation-specific) periodic interval.
• Media Session Handler sends QoE metrics reports at periodic interval specified in Service Access Information containing all of the metric values sampled since the last report was sent.

[dsilhavy]

Thanks @rjb1000

Media Session Handler sends QoE metrics reports at periodic interval specified in Service Access Information containing all of the metric values sampled since the last report was sent.

This periodic interval is in place and follows the reportingInterval value of the ServiceAccessInformation.clientMetricsReportingConfigurations

Media Stream Handler samples each metric at (currently implementation-specific) periodic interval.

This would indeed be required with the current implementaton as the buffer level is requested via the Exoplayer API and is currently not event driven like RepSwitch or HttpList. Maybe this would also be a configuration option provided via M8?

[rjb1000]

Maybe this would also be a configuration option provided via M8?

In a real world implementation, the QoE metrics sampling period is not something that would be signalled in a service catalogue feed at reference point M8 (think DVB-I).

Ideally, the M1 and M5 APIs would be extended to explicitly specify the data sampling period to the Media Session Handler. I suggest you raise an issue in 5G-MAG/Standards.

But, as a short term measure, I think that adding a configuration parameter to our test M8 feed isn't an unreasonable way of temporarily compensating for this gap in the specifications.

[dsilhavy]

Similar to RepresentationSwitch and HttpList I am capturing the BufferLevel based on events now:

• When segment download is completed
• When a buffering event is thrown

A period timeout solution would also be possible if signaled via M8 or M5 (see above). However, the ExoPlayer API endpoints can only be called from the main thread so we cannot simply use a timer function for this. We will need to use something like a Handler to post a Runnable on the main thread.

Example report as currently generated:

        <QoeMetric>
            <BufferLevel>
                <BufferLevelEntry level="29992" t="1688980890949" />
                <BufferLevelEntry level="31886" t="1688980891024" />
                <BufferLevelEntry level="29972" t="1688980892972" />
                <BufferLevelEntry level="31918" t="1688980892996" />
                <BufferLevelEntry level="30013" t="1688980894929" />
                <BufferLevelEntry level="31898" t="1688980895019" />
                <BufferLevelEntry level="30020" t="1688980896923" />
                <BufferLevelEntry level="31869" t="1688980897041" />
                <BufferLevelEntry level="30021" t="1688980898921" />
            </BufferLevel>
        </QoeMetric>

[dsilhavy]

Implemented in #67