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Re: [media-and-entertainment] Frame accurate seeking of HTML5 MediaElement

From: François Daoust via GitHub <sysbot+gh@w3.org>
Date: Mon, 18 Jun 2018 13:44:03 +0000
To: public-web-and-tv@w3.org
Message-ID: <issue_comment.created-398058565-1529329442-sysbot+gh@w3.org>
>> When you observe the .frameCounter for a element, say in requestAnimationFrame, which frame would that correspond to?
>
> For frame accuracy purposes, it should obviously correspond to the currently displayed frame on the screen.

@Daiz `requestAnimationFrame` typically runs at 50-60Hz, so once every 16-20ms, before the next repaint. You mentioned elsewhere that 15-30ms delays were noticeable for subtitles. Wouldn't it be more interesting to get the "frame that will be rendered on next repaint" instead, to avoid reacting up to 16ms late to a change of frame?

I'm not saying that it's easy to get from an implementation perspective, given the comment raised by @mfoltzgoogle https://github.com/w3c/media-and-entertainment/issues/4#issuecomment-396701652. In particular, I suspect browser repaints are not necessarily synchronized with video repaints, but the problem seems to exist in any case.

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Received on Monday, 18 June 2018 13:44:07 UTC

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