Suspected rounding error in MSE - content fails to play

Issue #16134130 • Assigned to John-David D.


Joey P.
Feb 27, 2018
This issue is public.
Found in
  • Microsoft Edge
Reported by 1 person

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Steps to reproduce

The bug can easily be seen in Shaka Player:;lang=en-US;play;build=uncompiled

On Chrome, Firefox, and Safari, the content starts playing back. In Edge, it does not, because the first GOP was removed. The second GOP starts at 1.541 seconds, and video.buffered.start(0) in the JS console produces 1.5416665.

It seems that a rounding error might be to blame. In this piece of content, we set timestampOffset to -705.9984537760416 (calculated from the manifest), then append a buffer whose first frame has DTS 8675309 and CTS 8676333, with timescale 12288. This translates to 705.998 seconds DTS and 706.082 seconds CTS.

As a workaround, fudging the timestampOffset by even 1 microsecond closer to zero seems to avoid the rounding error we presume is in Edge.


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    Comments and activity

    • This was originally brought to our attention here:

    • After fudging timestampOffset, I find that I must also offset the start of appendWindowStart to work around another rounding error at about 60s.

    • Microsoft Edge Team

      Changed Assigned To to “James M.”

      Changed Assigned To to “Venkat K.”

      Changed Assigned To from “Venkat K.” to “Shawn P.”

      Changed Assigned To from “Shawn P.” to “Gurpreet V.”

      Changed Assigned To from “Gurpreet V.” to “John-David D.”

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