Closed Bug 1311877 Opened 3 years ago Closed 3 years ago

VideoPlaybackQuality not returning amount of frames displayed or dropped.


(Core :: Audio/Video: Playback, defect, P3)




Tracking Status
firefox52 --- fixed


(Reporter: jya, Assigned: gerald)



(1 file)

Per spec:

"Each HTMLVideoElement MUST maintain a total video frame count variable keeping track of the total number of frames that have been displayed and dropped. It MUST follow these rules:

    It is initialized to 0 when the element is created.
    It is reset to 0 when the media element load algorithm is invoked.
    It is incremented when a video frame is displayed.
    It is incremented when the dropped video frame count is incremented

however, as seen with about:media
Quality: 100% (total:7 dropped:0 corrupted:0)
Buffered ranges: [(0, 8.982666)]
Internal Data:
audio decoder: apple CoreMedia decoder
audio frames decoded: 1
audio state: ni=0 no=0 ie=0 demuxr:0 demuxq:0 tt:-1.000000 tths:-1 in:1 out:1 qs=0 pending:0 waiting:0 sid:4294967295
video decoder: apple software VT decoder
hardware video decoding: disabled
video frames decoded: 1 (skipped:0)
video state: ni=0 no=0 ie=0 demuxr:0 demuxq:0 tt:-1.000000 tths:-1 in:7 out:1 qs=6 pending:0 waiting:0 sid:4294967295

So we have totalVideoFrameCount = 7, yet the number of frames returned by the decoder is 1.
The decoder has buffered 7 frames in total.

Or implementation uses the number of frames *parsed* as totalVideoFrames count.

A parsed frames doesn't equal the number of frames displayed nor the number of frames dropped as the spec requires.

The frames haven't been dropped yet, they are just buffered by the decoder as it has some latency due to how the h264 decoder works.
Thank you for noticing this.
Assignee: nobody → gsquelart
Comment on attachment 8803200 [details]
Bug 1311877 - VideoPlaybackQuality.totalVideoFrameCount is presented+dropped -
Attachment #8803200 - Flags: review?(jyavenard) → review+
Pushed by
VideoPlaybackQuality.totalVideoFrameCount is presented+dropped - r=jya
Closed: 3 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla52
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