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

From: Ingar Arntzen via GitHub <sysbot+gh@w3.org>
Date: Wed, 13 Jun 2018 10:18:43 +0000
To: public-web-and-tv@w3.org
Message-ID: <issue_comment.created-396888706-1528885122-sysbot+gh@w3.org>
With the timingsrc [1] library we are able to sync content changes outside the video with errors <10ms (less than a frame).

The library achieves this by

1) using an interpolated clock approximating currentTime (timingobject)
2) synchronizing video (mediasync) relative to a timing object (errors about 7ms)
3) synchronizing javascript cues (sequencer - based on setTimeout) relative to the same timing object (errors about 1ms)

This still leaves delays from DOM changes to on-screen rendering.

In any case, this should typically be sub-framerate sync. 

This assumes that currentTime is a good representation of the reality of video presentation. If it isn't, but you know how wrong it is, you can easily compensate.

Not sure if this is relevant to the original issue, which I understood to be about accurate frame stepping - not sync during playback?

Ingar Arntzen

[1] https://webtiming.github.io/timingsrc/

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Received on Wednesday, 13 June 2018 10:18:46 UTC

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