Re: AudioBufferSourceNode.buffer how to work it.

On Tue, Mar 11, 2014 at 2:03 AM, KeonHo Kim <keonho07.kim@samsung.com>wrote:

> Dear All.
>
>
>
> If there is setting a buffer of AudioBufferSourceNode, how it should work?
>
> I think that AudioBufferSourceNode.buffer should be able to set buffer
> anytime whatever the node is playing or not.
>
> I believe if all cases are able to JS developer, it is fantastic.
>
>
I think that in all of the cases below, you don't have sample accurate
timing. The sound for meaningfulbuffer will start at some uncontrolled time
after setting the buffer.  I think in all cases you can get the effect you
want by just creating a new AudioBufferSourceNode with the appropriate
buffer and calling start and stop appropriately.

Chris Rogers certainly intended that AudioBufferSourceNodes to be cheap to
create and use.

>
>
> < case1 >
> sourcenode.buffer = null;
> sourcenode.start(0); // mute
> ...
> sourcenode.buffer = meaningfulbuffer; // sound
>

This case is, I think, currently supported, but I find it's behavior odd
because the sound will start at some uncontrolled time.

> < case2 >
> sourcenode.buffer = meaningfulbuffer;
> sourcenode.start(0); // sound
> ...
> sourcenode.buffer = null; // mute
> ...
> sourcenode.buffer = meaningfulbuffer; // sound
>

I think this is better done by calling sourcenode.stop() instead of setting
the buffer to null.  Then create a new new node with meaningfulbuffer.


> < case 3 >
> sourcenode.start(0);
> sourcenode.buffer = meaningfulbuffer; // sound
>

I think this is the same as case 1

> < case 4 >
> sourcenode.buffer = meaningfulbuffer;
> sourcenode.start(0); // sound
>

This is the normal case.

> < case 5 >
> sourcenode.buffer = meaningfulbuffer1;
> sourcenode.start(0); // sound buffer1
>
> …
>
> sourcenode.buffer = meaningfulbuffer2;
>
> sourcenode.start(0); // sound buffer2
>
>
I don't know how that is supposed to work, especially since start() is only
allowed to be called once for each AudioBufferSourceNode.  Even if you
allowed more than one call, I still don't know how this is supposed to
behave.


--
Ray


>
>
>
>
> In spec, nullable buffer is existed which has mono channel silence can
> help making source muted to AudioBufferSourceNode without stop().
>
> If setting buffer or calling start() is allowed more than once,
> AudioBufferSourceNode can be reused.
>
>
>
> Is there any confirmed change about calling start() multiple times?
>
>
>
>
>
> However, it also has some issue.
>
> “The spec doesn't say, but the buffer attribute of an
> AudioBufferSourceNode should probably be only settable once.
>
> If you've started the source node and change the buffer while the previous
> buffer is playing, you have no control over when the new source starts.”
>
> https://github.com/WebAudio/web-audio-api/issues/288
>
>
>
> Please feel free to give your opinion and correct way for Web Audio API.
>
>
>
> Br,
>
> Khno
>
>
>