Re: Creating ADSR Envelopes

but since the value is scheduled for the future, reading it's .value would
not be the same by the time i actually want to ramp to the attack.

param.cancelScheduledValues(time)
param.setValueAtTime(param.value, time);

this only works if the time=currentTime, not any point in the future.

if i triggerAttack(context.currentTime + .2), my triggerAttack function
sets the value at the current value which might be different (assuming the
release is still going on) by the time i actually want to schedule my ramp.


On Thu, Jan 10, 2013 at 11:58 AM, Chris Rogers <crogers@google.com> wrote:

>
>
> On Thu, Jan 10, 2013 at 11:54 AM, Yotam Mann <matoyotambien@gmail.com>wrote:
>
>> yes! it does work on Canary. that's a relief.
>>
>> the first part of my question is mostly pertaining to envelope
>> retriggers. If i schedule an envelope with a very long release, and then at
>> some later point while that release is still going on, i get a callback to
>> schedule another envelope 0.02s in the future, i would like next envelope's
>> attack starting value to begin where the current release has left off (even
>> if it never makes it to 0).
>>
>> maybe this question comes out of ignorance for how the AudioParam's
>> values are calculated when there are multiple values scheduled.
>>
>> here is an simplified example of what i'm talking about:
>>
>> function triggerAttack (time) {
>>   param.linearRampToValue(1, time+attackTime);
>>   param.linearRampToValue(sustainValue, time+attackTime+decayTime);
>> }
>>
>> function triggerRelease (time){
>>   param.linearRampToValue(0, time+releaseTime);
>> }
>>
>> if i retrigger the attack while the release is still going on, how is the
>> attack duration and value calculated? my understanding was that i needed to
>> schedule a value at the start of the attack so that the attack will be
>> correctly ramped, so i usually write something like this:
>>
>> function triggerAttack (time) {
>>   param.setValueAtTime(*SOME VALUE?*, time);
>>   param.linearRampToValue(1, time+attackTime);
>>   param.linearRampToValue(sustainValue, time+attackTime+decayTime);
>> }
>>
>> but, i don't know what the value at the param time of the attack is since
>> the release is still going on.
>>
>
> You should be able to cancel all scheduled values with:
> param.cancelScheduledValues(0);
>
> Then simply read the .value attribute to get its current value.
>
>
>>
>> does that make sense?
>>
>>
>>
>> On Thu, Jan 10, 2013 at 11:08 AM, Chris Wilson <cwilso@google.com> wrote:
>>
>>> Hey Yotam,
>>>
>>> I'm not sure I understand the first half of your statement - if you know
>>> when in the future you will be scheduling another envelope, can't you use
>>> ramps to that time?  This seems like "I want the release to start 0.02s
>>> after I receive this JS event", or something like that - is this correct?
>>>
>>> That aside, the filter frequency should work as you surmise; however,
>>> there was a bug in that for a while.  Are you using Chrome Canary (i.e.
>>> version 26.xx?)
>>>
>>> -Chris
>>>
>>>
>>> On Thu, Jan 10, 2013 at 11:00 AM, Yotam Mann <matoyotambien@gmail.com>wrote:
>>>
>>>> Hi group,
>>>>
>>>> I'm working on a synthesizer in Web Audio and i'm stuck on the filter
>>>> envelope part.
>>>>
>>>> One issue that i'm having is that the pattern that I see often for
>>>> avoiding clicks when scheduling AudioParam's envelopes doesn't work when
>>>> scheduling the envelope in the future where the AudioParam's current value
>>>> is no longer the same:
>>>>
>>>> i.e. AudioParam.setValueAtTime(AudioParam.value, context.currentTime);
>>>>
>>>> If i want to schedule the next envelope in the future, but don't know
>>>> if the previous envelope's release has finished, i can't have the future
>>>> attack start where the previous envelope's release left off since there is
>>>> not getValueAtTime function for AudioParams.
>>>>
>>>> For this reason, i decided to make my own envelope generator with a
>>>> ScriptNode. This works well when I connect this signal to an oscillator's
>>>> gain, but I also want to apply the envelope to a filter's frequency
>>>> AudioParam. I scale the ADSR values to be between 0 and 500 for example and
>>>> connect it to the filter.frequency, but it doesn't not seem to be making
>>>> any difference. does this filter's frequency AudioParam not behave the same
>>>> as the gain's gain param?
>>>>
>>>> Insight on these issues would be greatly appreciated.
>>>>
>>>> thanks.
>>>>
>>>> Yotam
>>>>
>>>
>>>
>>
>