VideoPlaybackQuality not returning amount of frames displayed or dropped.

RESOLVED FIXED in Firefox 52

Status

()

P3
normal
RESOLVED FIXED
2 years ago
2 years ago

People

(Reporter: jya, Assigned: gerald)

Tracking

unspecified
mozilla52
Points:
---

Firefox Tracking Flags

(firefox52 fixed)

Details

Attachments

(1 attachment)

(Reporter)

Description

2 years ago
Per spec:
VideoPlaybackQuality

https://wicg.github.io/media-playback-quality/#concepts

"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.
(Assignee)

Comment 1

2 years ago
Thank you for noticing this.
Assignee: nobody → gsquelart
Comment hidden (mozreview-request)
(Reporter)

Comment 3

2 years ago
mozreview-review
Comment on attachment 8803200 [details]
Bug 1311877 - VideoPlaybackQuality.totalVideoFrameCount is presented+dropped -

https://reviewboard.mozilla.org/r/87482/#review86444
Attachment #8803200 - Flags: review?(jyavenard) → review+

Comment 4

2 years ago
Pushed by gsquelart@mozilla.com:
https://hg.mozilla.org/integration/autoland/rev/6ac2e1d8d2c8
VideoPlaybackQuality.totalVideoFrameCount is presented+dropped - r=jya

Comment 5

2 years ago
bugherder
https://hg.mozilla.org/mozilla-central/rev/6ac2e1d8d2c8
Status: NEW → RESOLVED
Last Resolved: 2 years ago
status-firefox52: --- → fixed
Resolution: --- → FIXED
Target Milestone: --- → mozilla52
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