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Re: Behavior of source nodes on connect/disconnect

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 13 Sep 2013 16:13:57 -0700
Message-ID: <CAOp6jLbhcxqptz1JNGtWx=S6xDMQ8L+3UGUZGgj4fHONRdnu1g@mail.gmail.com>
To: Jer Noble <jer.noble@apple.com>
Cc: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>, Chris Wilson <cwilso@google.com>, Raymond Toy <rtoy@google.com>, "public-audio@w3.org" <public-audio@w3.org>
On Fri, Sep 13, 2013 at 1:46 PM, Jer Noble <jer.noble@apple.com> wrote:

> On Sep 13, 2013, at 1:38 PM, Robert O'Callahan <robert@ocallahan.org>
> wrote:
>
> Are you saying that the "pause nodes with no outputs" rule would be
> different for OfflineAudioContexts?
>
>
> No, I’m saying that you’d connect the ScriptProcessorNode to an
> OfflineAudioContext’s destinationNode and throw away the resulting
> AudioBuffers.
>

OK. It still seems weird to have to connect the ScriptProcessorNode's
output, which in this case is meaningless, to the destinationNode to get
the ScriptProcessorNode to work.

OfflineAudioContext will consume samples as fast as they are produced;
> presumably we would spec that MediaElementSourceNode will only produce
> samples at a 1 second-per-second rate.
>

I guess that works from a spec point of view. It does mean that we can
switch dynamically between "go as fast as you can" to "advance in real
time" depending on whether a MediaElementSourceNode is connected. That's
hard for us to implement, and even harder for a MediaStreamAudioSourceNode.
Anyway it's a separate issue that I don't want to be mixed in here.

If you are analyzing a subgraph that’s actually connected to a live
> destination, this seems moot, as we’re no longer talking about a
> disconnected subgraph.
>

Well then, I don't know exactly what you're proposing here. I thought the
proposed rule was that any node whose output is not directly or indirectly
connected to a DestinationNode is paused. But you seem to be saying that a
node is not paused if it has any input that is not paused.

This is why it would be good to work out an actual spec proposal for what
you want :-).

Rob
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Received on Friday, 13 September 2013 23:14:25 UTC

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