[mediacapture-record] MediaRecorder BlobEvent timecode clarification (#222)

bradisbell has just created a new issue for https://github.com/w3c/mediacapture-record:

== MediaRecorder BlobEvent timecode clarification ==
From:  https://w3c.github.io/mediacapture-record/#dom-blobeventinit-timecode

> `timecode`, of type `DOMHighResTimeStamp`, readonly
> The difference between the timestamp of the first chunk in data and the timestamp of the first chunk in the first BlobEvent produced by this recorder as a DOMHighResTimeStamp [HR-TIME]. Note that the timecode in the first produced BlobEvent does not need to be zero.

I don't think I've ever fully understand this sentence.  If this is the value of the timestamp of the first chunk in `data`, compared to the value of the first chunk in `data` of the first event produced by this recorder, and if this is the first event, how could the value of `timecode` not be zero `0`?

I believe at some point in the past, `timecode` would actually start at zero `0` for the first event, and then subsequent `dataavailable` `BlobEvent` `timecode` could be used to determine the duration of recorded MediaStream data thus far.  It seems that the current way is to note the first event's `timecode` and offset subsequent `timecode` events by that first event's `timecode` value to see how much time has passed.  That's fine, but depends on the assumption that the first event's `timecode` is the zero relative to other events.

Please view or discuss this issue at https://github.com/w3c/mediacapture-record/issues/222 using your GitHub account


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Received on Monday, 17 June 2024 06:08:09 UTC