[Bug 22148] New: Request that we reconsider adding jitter to video quality metrics

https://www.w3.org/Bugs/Public/show_bug.cgi?id=22148

            Bug ID: 22148
           Summary: Request that we reconsider adding jitter to video
                    quality metrics
    Classification: Unclassified
           Product: HTML WG
           Version: unspecified
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Media Source Extensions
          Assignee: adrianba@microsoft.com
          Reporter: jdsmith@microsoft.com
        QA Contact: public-html-bugzilla@w3.org
                CC: mike@w3.org, public-html-media@w3.org

We have partner feedback indicating that jitter is very useful as a feedback
mechanism for video quality.  It allows detection of situations where no frames
are dropped, but jitter is sufficient to be visible to users.

Restoring it would mean changing the video quality metrics to this, based on
the currently adopted metrics:

interface MediaPlaybackQuality {
    readonly    attribute DOMHighResTimeStamp creationTime;
    readonly    attribute unsigned long       totalVideoFrames;
    readonly    attribute unsigned long       droppedVideoFrames;
    readonly    attribute double           playbackJitter;
};

The "playbackJitter" attribute represents the sum of all duration errors for
frames intended to be presented to the user, where: 

Ei = Desired duration of frame i spent on the screen (to nearest microsecond) 

Ai = Actual duration frame i spent on the screen (if the frame is never
presented to the user, then Ai == 0). 

then: playbackJitter = sum(abs(Ei - Ai))

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Received on Thursday, 23 May 2013 00:22:10 UTC