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Re: [Bug 17793] New: AudioNode.disconnect() needs to be able to disconnect only one connection

From: Chris Wilson <cwilso@google.com>
Date: Tue, 17 Jul 2012 12:46:28 -0700
Message-ID: <CAJK2wqXGSJXCr1XWjU4tXWzHUvKF1MoqjQE-5qL1-iFCd2NrZw@mail.gmail.com>
To: Peter van der Noord <peterdunord@gmail.com>
Cc: public-audio@w3.org
The "input" and "output" parameters on connect & disconnect were initially
quite misleading to me - because you will only use them for nodes that
explicitly offer separate inputs or outputs (notably - the
AudioChannelSplitter and AudioChannelMerger).  These indices do NOT refer
to the fan-out of connecting one node to multiple other nodes, or the
mix-in of connecting multiple nodes to one "destination" node; they refer
to different "channels" of a connection.  Therefore, you CAN connect one
output to two different inputs on another node; for example, you might do
this if you wanted the left channel from one node to be copied to the right
AND left channels in another node.

For all scenarios where you are not explicitly interested in the multiple
channels, you don't need to supply these parameters at all.  Perhaps they
should be renamed "channels" for this reason, I don't know.

So, if you have this case

nodeA.connect( nodeB );
nodeA.connect( nodeC );

there is currently no way to disconnect nodeA from nodeB, without also
disconnecting nodeA from nodeC.

And yes, I did explicitly test to make sure that making multiple
connections from one node to another does not sum up the connections -

nodeA.connect( nodeB );
nodeA.connect( nodeB );

gives the same output as

nodeA.connect( nodeB );

It does not explicitly fail, it is just ignored.

On Tue, Jul 17, 2012 at 11:51 AM, Peter van der Noord <peterdunord@gmail.com
> wrote:

> > Recommended solution:
> > - there should be a way to remove a single connection (by supplying the
> > destination node to be disconnected, since there can only be one
> connection to
> > a given destination node [tested]).
> >
> > E.g.: the IDL for disconnect should read:
> >
> >         void disconnect(in [Optional] AudioNode destination, in
> [Optional]
> > unsigned long output = 0)
> >             raises(DOMException);
> >
> > this lets us keep most compatibility - node.disconnect() will still
> remove all
> > connections.
> I'm confused now.
> " node.disconnect() will still remove all connections."
> Is this the case? That would help me a lot. I only now see in the draft
> that the in-parameter is optional, so: does not supplying any params to the
> disconnect method remove the whole node with every connection to and from
> it like that uote says? If so, that is not mentioned in the explanation in
> the draft, it's even incorrect:
> Disconnects an AudioNode's output.
> The output parameter is an index describing which output of the AudioNode
> to disconnect. An out-of-bound value throws an exception.
> Then: "(by supplying the destination node to be disconnected, since there
> can only be one connection to a given destination node [tested])."
> I was already wondering what would happen if i tried to connect the same
> output and same input twice (i guessed it would fail...does it?) but this
> implies even more. Nodes can have multiple inputs and outputs, and by
> reading this sentence i understand i wouldn't be able to connect for
> example one output to two different inputs on another node. That can't be
> right, i think you should supply a node *with* the index of the input,
> instead of just the node.
> Peter
Received on Tuesday, 17 July 2012 19:46:57 UTC

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