Hi all,

Thought this might be of interest to developers of OSC externals.

In short: Pd OSC implementations should send OSC on the same port that they listen on, as that is the "standard" way OSC works.

Claude

-------- Original Message -------- Subject: Re: [sc-users] NetAddr Date: Tue, 04 Mar 2008 21:48:37 -0500 From: nescivi Reply-To: SuperCollider users mailing list sc-users@create.ucsb.edu To: SuperCollider users mailing list sc-users@create.ucsb.edu

Hiho,

On Tuesday 04 March 2008 21:28:27 William Brent wrote:

Hmm. I've been doing a little more testing on this, using two separate machines. Here's what seems to be true:

1. With both machines using SC, OSC messaging is fine through port 57120.

Each side simply specifies

n = NetAddr("address of other machine", 57120); o = OSCresponder(n, '/chat', { |t, r, msg| msg.postln }).add;

n.sendMsg("/chat", "blah");

This means each machine is listening for messages *from* the address of the other machine, on port 57120, and sending messages *to* the other addresss on port 57120.

So within SC, of course, all is well.

correct, since SC sends from the same port as that it listens to, which is as it should be. In OSC world it is custom to send reply messages, so from the received message you are able to figure out from which ip and port is was sent, so you can back a message.

2. OSC communication between Max and Max, Pd and Pd, or Pd and Max is all

fine.

3. Using either the sendOSC object in Pd, or the udpsend object in Max/MSP,

communication with SC fails unless SC's OSCresponder addr argument is set to nil. This is in spite of the fact that sendOSC and udpsend require you to specify the address and port number you'd like to send *to*.

Again, there is a difference between the address they are sending from and sending to. Like putting your address on a letter you send by snail mail. It gives the receiver a method to figure out where the letter came from, and enables him to send a letter back.

There is no way to specify what port you're sending *from* on the Pd or Max machines, but I've been told that if you're sending to a specific port on another machine, the local machine must necessarily be sending out the same port. I have no idea if that's true or not...

no. The fact that there is no way to specify *from* which Pd or Max are sending is a weakness on their side. They should either let you specify it, or document which port they are using. But chances are that they just take any port, in which case you have no other option than to use nil in the OSCresponder.

But maybe Max and Pd are consistent in their behaviour.

I am not entirely sure whether this will work, for lack of Pd on my system, but possibly with this bit of code, you van figure out from which address Pd is sending.

o = OSCresponder(nil, '/chat', { |t, r, msg, addr| addr.postln; }).add;

I think it should post the addr. that the message comes from; please test this by banging your sendOSC object multiple times to see if it is consistent.

So, in a way, there's no problem, as long as you explicitly specify no NetAddr to listen for. A friend of mine did a piece by Paul Lansky that required SC/Max communication, and that code also has OSCresponders listening to a "nil" NetAddr, since it was the only way to make it happen.

I don't know enough about this to suggest what's going on. Maybe I'm still missing something (and sorry if I am!), but it seems like there could be a problem on the SC side here...

nope, the problem is on the other side. SC allows for a safe mechanism by only listening to one specific port. It is up to the sending application to provide an equally safe mechanism to send messages out.

sincerely, Marije _______________________________________________ sc-users mailing list sc-users@create.ucsb.edu http://lists.create.ucsb.edu/mailman/listinfo/sc-users