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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 17:08:09 +0000
To: public-web-and-tv@w3.org
Message-ID: <issue_comment.created-397014061-1528909688-sysbot+gh@w3.org>
@chrisn 

> Presumably, frame accurate time reporting would help with synchronised media playback across multiple devices, particularly where different browser engines are involved, each with a different pipeline delay. But, you say you're already achieving sub-frame rate sync in your library, based on currentTime, so maybe not?

So, while the results are pretty good, there is no way to ensure that they are always that good (or thay they will stay this good), unless these issues on the agenda through standardization work.

There are a number of ways to improve/simplify sync.
- as you say, exposing accurate information on downstream delays, frame count, media offset is always a good thing.
- currentTime values are also not timestamped, which means that you dont really know when it was sampled internally.
- The jitter of currentTime is terrible. 
- Good sync depends on an interpolated clock. I guess this would also make it easier to convert back and forth between media offset and frame numbers.
- there are also improvements *seekTo* and *playbackrate* which would improve things considerably 



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Received on Wednesday, 13 June 2018 17:08:14 UTC

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