fix can't change volume after it fadein

[krmbn0576]

RMMV's WebAudio contains several bugs.

• Can't change BGM volume after playing ME
• Can't change BGM volume after replaying BGM
• Can't change BGM and BGS volume after battle end

The cause of all these bugs is "Can't change volume after it fadein".

This is caused by the strange specification of WebAudio AudioParam. (For details, see WebAudio/web-audio-api#128)
Changes to value are ignored after setValueAtTime or linearRampToValueAtTime is called.
Therefore, I decided to cancel these schedules when changing value.

[ghost]

It works correctly?

Anxious comment is found : WebAudio/web-audio-api#128 (comment)

Maybe replace setting values directly to calling setValueAtTime() if it works.

[krmbn0576]

Hmm, In my Environment, it works correctly.

I think he/she misunderstood. setValueAtTime() is scheduling method, so value won't work. Only cancelScheduledValues() can cancel schedules and enable value.

[ghost]

I read the spec. setting value means calling setValueAtTime() at context's currentTime.

You'd better write cancelScheduledValues() just before automation methods being called.
There are some points to insert it.

[krmbn0576]

Hm, is it profitable?
I think this commit works correctly now.

[ghost]

Same problem is found some mehtods. :-<

ex. WebAudio._fadeIn
It's rare to be called. But when called, it causes same problem, so You'd better fix it.

[krmbn0576]

Hmm, it never causes the problem because _masterGainNode.gain.value is assigned only when created.
Do you think that any method should not cause bugs under any circumstances?
I think, not necessary.

[ghost]

Confusing, I tested current branch. (not this branch)
By the specification, value property and setValueAtTime is exactly same.
I can't understand why masterGainNode works and others not.

I found that volume works after using fadeIn. (Chrome 56.0.2924.87 Windows 10)
Is the bug from specific browser?

[ghost]

I cannot reproduce the problem, but LGTM if it works. 🍣

[krmbn0576]

I found that volume works after using fadeIn. (Chrome 56.0.2924.87 Windows 10)

Me too! However, the bug occurs in Firefox and Nwjs...

Hmm, AudioParam#value is very confusing.
I replaced them to AudioParam#setValueAtTime at context's currentTime.

But... oh no the situation got worse!
this commit works correctly in Nwjs, but Firefox51 still have the same bug...

[ghost]

Then, can you insert cancelScheduledValues() and test it by FF?

[krmbn0576]

I inserted this._gainNode.gain.cancelScheduledValues(0); at 270,
but FF still has the bug...

[ghost]

I see...

Call cancelScheduledValues() then set value and setValueAtTime().
If these work, please comment these are workaround for FF.

[krmbn0576]

OK, I completely made a mistake.
The real problem is Firefox load old (before modified) scripts until I push F5 key explicitly!!!(including XMLHTTPRequest)
Chrome always load latest ones, so I made a very easy mistake. 😂

This commit works correctly!

[ghost]

okay, LGTM 😇