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

From: KilroyHughes via GitHub <sysbot+gh@w3.org>
Date: Fri, 20 Jul 2018 08:58:57 +0000
To: public-web-and-tv@w3.org
Message-ID: <issue_comment.created-406536137-1532077136-sysbot+gh@w3.org>
One detail for such a document (I'm not volunteering to write) is video frame reordering. Widely deployed video codecs such as AVC reorder and often offset the presentation time of pictures relative to their order and timing in the compressed bitstream. For instance, frames 1, 2, 3, 4 in the compressed stream might be displayed in order e.g. 2, 1, 4, 3 and presentation time can be delayed several frames. Frame rate changes are not unusual in adaptively streamed video. Operations such as seeking, editing, and splicing of the compressed stream, e.g. in an MSE buffer, do not happen at the presentation times often assumed. Audio, TTML, HTML, events, etc. must take presentation reordering and delay into account for frame accurate synchronization at some "composition point" in the media pipeline. 

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Received on Friday, 20 July 2018 08:58:58 UTC

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