On 3/22/19 5:58 PM, Balaji Janakarajan Hari wrote:
Hi Josh
1. We are trying to implement the functionality and have a few q's. The
setValueCurveAtTime
<http://definitelytyped.org/docs/webaudioapi--waa/interfaces/audioparam.html#setvaluecurveattime>
talks
about Automation event, which I assume that the term
*UserAutomationEvent *refers
to in the issue <https://github.com/servo/media/issues/204> but could you
please help us understand what *UserAutomationEvent exactly* does and where
the *setValueCurveAtTime *fn would be called?
The names I refer to in the issue are types that can be found in the
actual codebase:
https://github.com/servo/media/blob/9d9f557fc7bfa78075b83edd822557548c9d4344/audio/src/param.rs#L259-L280
https://github.com/web-platform-tests/wpt/blob/master/webaudio/the-audio-api/the-audioparam-interface/audioparam-setValueCurveAtTime.html
is an example of test code that uses setValueCurveAtTime.
https://developer.mozilla.org/en-US/docs/Web/API/AudioParam/setValueCurveAtTime
contains an example of working code that uses the API.
2. Is there a similar implementation done previously that we could use as
reference as well?
The existing automation events like SetValueAtTime and RampToValueAtTime
could be useful references.
3. It does refer
<https://webaudio.github.io/web-audio-api/#dom-audioparam-setvaluecurveattime>that
I would need to call *setValueAtTime *and I assume this is implemented
<https://github.com/servo/media/search?q=setValueAtTime&unscoped_q=setValueAtTime>
as I see here and can you also let us know where the *setValueAtTime* is
defined?
If I understand the question, I believe you are looking for
https://github.com/servo/servo/issues/22897 which defines the DOM API
that websites can make use of.
4. The fn does two commands as per the teams understanding,
During the time interval, it sets array of values
After the time, startTime+duration, a constant value would be set until
another automationEvent starts.
So could you please help us in figuring out where would this value be
passed and where/how the fn knows that another automationEvent would start?
The processing for automation events happens in this code:
https://github.com/servo/media/blob/9d9f557fc7bfa78075b83edd822557548c9d4344/audio/src/param.rs#L357-L416
The code that decides which event to process lives here:
https://github.com/servo/media/blob/9d9f557fc7bfa78075b83edd822557548c9d4344/audio/src/param.rs#L113-L166
Does that help?
Cheers,
Josh
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