[Ardour-Dev] Osc and control surface

tom at trellis.ch tom at trellis.ch
Sat Mar 23 07:13:00 PDT 2013


> Now about that sysex. I understand that for switches this is an easy
> task. For fader control, how do I do this? The fader values needs to be
> mapped somewhere. In Osc I send db values and since osc have the
> /routes/gaindB it works perfect. Speaking of gaindB: actually it sends
> the other type (-1,1) which as I see it means that the mapping to the
> physical fader needs to be done somewhere else. Should it not be better
> to send the gaindB instead?

not sure this is related or may help you, i'm using this in an
intermediary between ardour and devices (audio faders):

/*map pos 0-1 to ardour non-linear fader*/
function sliderPosToGain(pos)
        return Math.pow

/*and vice versa non-linear gain 0-2 to pos 0-1*/
function gainToSliderPos(gain)
                return 0;

part of this could be inside ardour to make the api easier. needs some
more thinking though.

> To me it looks like
> 1) Ardour listens to port 3819 (or if it is occupied by me: ) 3920)
> 2) I send /routes/list to Ardour
> 3) Ardour answers on port 3819.
> 4) Since I cannot listen to port 3819 (Ardour is listening on this
> port) on localhost I cannot receive the message.

this seems wrong. if you send /routes/list to ardour, it will reply to the
port the message was sent. you could use osc console
(http://lowres.ch/oscc/) to check that. simply start it with ./OSC_CONSOLE
1234 localhost 3819 and then /ardour/list -> you will get reply on port
1234. the format is somehow exotic (#reply).

the problem that some tools _can not_ send and receive osc on the same
port is a limitation of those programs. technically, there is no problem
with that.

using an intermediary you can map whatever you like. i use it for instance
to control LED on buttons on external interface (along other ops):

[reloop rmp3 in midi mode]----midi--->[jack_midi_to_osc]            
[ardour 3]
                       /\                               \ (osc)         /|
                         \                               \               |
                          \                               \|            \|
                           \                            [oscc with app
                            \                                  |

however, i see some potential to consolidate some aspects how the osc api
works today in the future. i've started to use it and while doing that
also made some minor mods that need to be cleaned. osc is clearly not a
replacement for midi. the advantage (and at the same time some downsides)
of osc is it's openness.

best regards,

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