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Issue metadata

Status: WontFix
Owner: ----
Closed: Dec 2017
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: All
Pri: 2
Type: Bug



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<video> tag time information shows garbage when playing back a MediaStream

Project Member Reported by mcasas@chromium.org, Mar 4 2017

Issue description

When plugging a MediaStream into a <video> tag, the playback
timing information is garbage, i.e. it's not either the amount
of time the capture has been going on nor the amount of time
the playback itself has been going on, but instead it shows
what I believe is the system timestamp-from-epoch (see pic);

This is totally reproducible using codepen [1].

It's a pity for captureStream() cases, where users expect
the playback time to make sense.

[1] https://codepen.io/miguelao/pen/KWMVZP?editors=0010



UserAgentString: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3026.0 Safari/537.36




 
le_corrupted_time.png
7.5 KB View Download
AFAICT https://w3c.github.io/mediacapture-fromelement/ does not define the behavior. File a spec issue?
Cc: hta@chromium.org
#1: I'm not sure but this might also affect MediaStream(Track) definition, 
right?  -fromelement might have some extra information though, like 
specifying that the generated stream time reference should be the 
"creation" or "the first information flow"; note that the codepen uses
a webcam.

hta@ what's supposed to show from the spec POV when we plug a MStream
intoa <video> element?

Comment 3 by mcasas@chromium.org, Mar 14 2017

Found the Spec entry (6. MediaStreams in Media Elements) [1]:

> The timeline starts at 0 and increments linearly in real time as long as the MediaStream is playing. The timeline does not increment when the playout of the MediaStream is paused.

[1] https://w3c.github.io/mediacapture-main/#mediastreams-in-media-elements

Comment 4 by foolip@chromium.org, Mar 20 2017

What might "the playout of the MediaStream is paused" mean? It sounds like it means that the media element is paused, but it wouldn't make sense for the time of the MediaStream to be affected by that I think. A single MediaStream could be connected to multiple media elements where only one is paused, and so on.

If the currentTime (and video frame) of a paused media element stays fixed and then jumps to the current time when unpaused, some bit of spec language needs to explain that, however.
Still available.

Comment 6 by mcasas@chromium.org, Dec 18 2017

Status: WontFix (was: Available)
This seems to have been solved by itself, yay! 
but hasn't been triaged or anything ♒((⇀‸↼))♒

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