[Bug 20698] Need way to determine "performance.now()" time of current audio output


Chris Wilson <cwilso@gmail.com> changed:

           What    |Removed                     |Added
                 CC|                            |cwilso@gmail.com

--- Comment #2 from Chris Wilson <cwilso@gmail.com> ---
Can we clearly delineate?  I'm not positive I understand what "latency
discovery" is, because there's one bit of information (the average processing
block size) that might be interesting, but I intended this issue to cover the
explicit "I need to synchronize between the audio time clock and the
performance clock at a reasonably high precision - that is, for example:

1) I want to be playing a looped sequence through Web Audio; when I get a
timestamped MIDI message (or keypress, for that matter), I want to be able to
record it and play that sequence back at the right time.

2) I want to be able to play back a sequence of combined MIDI messages and Web
Audio, and have them synchronized to a sub-latency level (given the latency
today on Linux and even Windows, this is a requirement).  Even if my latency of
Web Audio playback is 20ms, I should be able to pre-schedule MIDI and audio
events to occur within a millisecond or so of each other.

Now, there's a level of planning for which knowing the "average latency" -
related to processing block size, I imagine - would be interesting (I could use
that to pick a latency in my scheduler, for example); but that's not the same
thing.  Perhaps these should be solved together, but I don't want the former to
be dropped in favor of the latter.

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Received on Tuesday, 2 April 2013 14:30:45 UTC