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

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/



2018-06-13 8:20 GMT+02:00 Jon Piesing via GitHub <sysbot+gh@w3.org>:

> It depends on the inputs to the custom subtitle rendering algorithm. How
>> do you determine when to render a text cue?
>>
>
> Perhaps @palemieux could comment on how the imsc.js library handles this?
>
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