[Webkit-unassigned] [Bug 273103] HTMLVideoElement "playing" event triggered unexpectedly

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=273103

--- Comment #4 from Jean-Yves Avenard [:jya] <jean-yves.avenard at apple.com> ---
I'm not sure I understand what the problem ism and I think there's some confusion presents here.

`canplay` is fired when readyState is 3 (HAVE_FUTURE_DATA), HAVE_FUTURE_DATA only indicates at least one more frame than the current frame.

`canplaythrough` is emitted when readyState is 4 (HAVE_ENOUGH_DATA) which per spec indicates 
```
The user agent estimates that data is being fetched at a rate where the current playback position, if it were to advance at the element's playbackRate, would not overtake the available data before playback reaches the end of the media resource.
```

the player is to resume only when readyState is 4 after stalling (that is readyState when back to 2)

In your screen capture, we can see that after readyState reached HAVE_FUTURE_DATA, we have two `progress` event being fired: so the user agent is actively downloading content here. 

- we see that readyState reach the value of 3, `canplay` is fired as per spec [1]
- `progress` is fired as data was downloaded [2]
- `stalled` is fired, likely because decoding the next frame has completed and no new download was there (can't tell as there's no timestamps attached to this screen) [3]
- play() is called so `playing` is fired [4] as the paused attribute is now false.
- another `progress` event as above
- now readyState reaches 4 we have reached enough data for playback to start, as currentTime starts progressing `timeupdate` is fired [5]

There's nothing in the data provided indicated an incorrect behaviour that isn't following the specs.

Even if the readyState is 3, and the paused attribute is false (the `playing` event got fired:
```
Even if this event fires, the element might still not be potentially playing, e.g. if the element is paused for user interaction or paused for in-band content.
``` (that list isn't exhaustive as it's non-normative)

>From your list of observations, I see nothing incorrect here and would need further description of what you believe is incorrect and what you were expecting instead.

If your bug report is:
"We observed that the "playing" event triggers before the video player is potentially playing (https://html.spec.whatwg.org/multipage/media.html#event-media-playing) on Safari browsers"

that is *not* a bug, this webkit is 100% per spec here as per [1]: readyState >= 3 and paused == false.
`playing` doesn't indicate that currentTime is progressing at this stage yet.


[1] https://html.spec.whatwg.org/multipage/media.html#event-media-playing
[2] https://html.spec.whatwg.org/multipage/media.html#event-media-progress
[3] https://html.spec.whatwg.org/multipage/media.html#event-media-stalled
[4] https://html.spec.whatwg.org/multipage/media.html#event-media-playing
[5] https://html.spec.whatwg.org/multipage/media.html#event-media-timeupdate

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