--- layout: default title: OSC Feedback With Ardour ---

Feedback from the Ardour to the the control surface is very useful for a number of things. Motor faders need to know where the the track they have been attached to is at before they were assigned otherwise they will jump to where the local fader is. Likewise, the buttons on each strip need to know what there value is so they can light there LED correctly. Transport controls should let you know if they are active too. This is what feedback is all about.

Ardour does feedback by sending the same path back that is used to control the same function. As such any controls that have feedback have a parameter that is the value of the control or it's state (on or off). In the case of OSC paths listed on the main OSC page as having no parameter, if they have feedback, they will also work with a 1 for button press and 0 for button release. This is because many OSC controllers will only use exactly the same path for feedback as for control. For example:

/transport_stop

can be used also in the form:

/transport_stop press
where press is an int/bool indicating if the button is pressed or not.

The feedback does not have the same meaning as the control message. Rather, the feedback will be:

/transport_stop state
where state is an int/bool indicating if the transport is stopped or not.

List of OSC feedback messages

Feedback only

These messages are feedback only. They are sent as status from Ardour and some of them may be enabled separately from other feedback. See: Calculating Feedback and Strip-types Values.

See strip section below for info about ssid and wrapping it into the path.

/strip/name ssid track_name
where track_name is a string representing the name of the track
/session_name session_name
where session_name is a string representing the name of the session
/strip/meter ssid meter
where meter is a value repesenting the current audio level. (the exact math used is determined by the feedback bits set)
/strip/signal ssid signal
where signal is a float indicating the instantainious audio level is -40dB or higher.
/timecode time
where time is a string with the current play head time.
/bar_beat beat
where beat is a string with the current play head bar/beat.
/heartbeat LED
where LED is a float that cycles 1/0 at 1 second intervals.
/record_tally state
Some record enable is true or "ready to record"

Transport Control

/transport_stop state
/transport_play state
/ffwd state
/rewind state
/loop_toggle state

Recording control

/rec_enable_toggle state
Master record enabled.

Master and monitor strips

Master and monitor strips are similar to track strips but do not use the SSID. Rather they use their name as part of the path:

/master/gain dB
where dB is a float ranging from -193 to +6 representing the actual gain of master in dB
/master/fader position
where position is an int ranging from 0 to 1023 representing the fader control position
/master/trimdB dB
where dB is a float ranging from -20 to +20 representing the actual trim for master in dB
/master/pan_stereo_position position
where position is a float ranging from 0 to 1 representing the actual pan position for master
/master/mute yn
where yn is a bool/int representing the actual mute state of the Master strip
/monitor/gain dB
where dB is a float ranging from -193 to 6 representing the actual gain of monitor in dB
/monitor/fader position
where position is an int ranging from 0 to 1023 representing the fader control position

Track specific operations

For each of the following, ssid is the surface strip ID for the track

Some Surfaces (many Android applets) are not able to deal with more than one parameter in a command. However, the two parameter commands below can also be sent as /strip/command/ssid param. Feedback can be set to match this with the /set_surface/feedback state command. See Calculating Feedback and Strip-types Values.

/strip/name ssid track_name
where track_name is a string representing the name of the track (note there is no coresponding command to set the track name)
/strip/mute ssid mute_st
where mute_st is a bool/int representing the actual mute state of the track
/strip/solo ssid solo_st
where solo_st is a bool/int representing the actual solo state of the track
/strip/monitor_input ssid monitor_st
where monitor_st is a bool/int. True/1 meaning the track is force to monitor input
/strip/monitor_disk ssid monitor_st
where monitor_st is a bool/int. True/1 meaning the track is force to monitor disk, where both disk and input are false/0, auto monitoring is used.
/strip/recenable ssid rec_st
where rec_st is a bool/int representing the actual rec state of the track
/strip/record_safe ssid rec_st
where rec_st is a bool/int representing the actual record safe state of the track
/strip/gain ssid gain
where gain is a float ranging from -193 to 6 representing the actual gain of the track in dB.
/strip/fader ssid position
where position is an int ranging from 0 to 1023 representing the actual gain of the track in dB.
/strip/trimdB ssid trim_db
where trim_db is a float ranging from -20 to 20 representing the actual trim of the track in dB.
/strip/pan_stereo_position ssid position
where position is a float ranging from 0 to 1 representing the actual pan position of the track

Menu actions

Every single menu item in Ardour's GUI is accessible via OSC. However, there is no provision for returning the state of anything set this way. This is not a bad thing as most menu items either do not have an on/off state or that state is quite visible. Binding that affect other parameters that OSC does track will show on those OSC controls. Examples of this might be track record enable for tracks 1 to 32, play or stop.