OSC lets synthesizers and other devices communicate with Ardour. OSC devices can send commands relating to playback (such as play or stop), performance (such as volume, play, stop, and almost any other function (such as Edit, or Undo).

Note: OSC control has changed dramatically since Ardour 4.7. The Path structure has been completely redone, Banking has been introduced, The controller is now able to tell Ardour what kind of feedback it can work with (including bank size) and two new math styles have been added to gain controls. If you are using an Ardour version of 4.7 or less, please read Osc control in ardour 4.7 and prior.

Ardour is probably one of the most OSC-controllable audio applications around, but as with all OSC-controllable apps, you can't do much without knowing what messages can be sent. This document describes the various categories of messages that Ardour understands. It is subject to change, particularly the "Actions" part below, since this relates to the GTK GUI for Ardour rather than the backend.

Connecting to Ardour via OSC

OSC support is not enabled by default, but can be turned on via Edit > Preferences > Control Surfaces. Once enabled, Ardour will listen on port 3819 by default. This port number can be changed by editing $ARDOUR_CONFIG and adding this line within the <Config> section:

<Option name="osc-port" value="Your choice here"/>

Ardour sends any feedback to the port and address that sent any feedback request. The port does not have to match Ardour's port. In fact it is better not to. This means that Ardour can deal with more than one controller at a time. The two controllers can bank independently and even use different math for faders. This could be used to allow talent to adjust their own monitor mix using a tablet or phone that can run an OSC controller. For a full explanation of how Ardour's feedback works please read OSC feedback In Ardour.

Control Surface Set Up

Control surface set up allows the controller to tell Ardour about it's capabilities. The surface can tell Ardour how many control strips it has for banking, if it is capable of setting it's faders or buttons to values set by Ardour's GUI or automation, What kind of math the faders use and more.

Any time the /set_surface command is sent, the current bank is recalculated and if feedback is turned on, the values of each strip's controls are sent (or refreshed) as well. This will also refresh the Master feedback setup.

Surface Port Setting is available in the OSC GUI.

As of Ardour 5.1, There is now a GUI setup in response to those using tablets with applications such as touchOSC or AndrOSC who need to be able to set a port for Ardour to send to. It can also change the default setting for set_surface. For more information about Ardour's OSC configuration GUI please read Ardour's Setup Dialog.

If /set_surface is not sent, the default values are used:

These values give the same behaviour as prior versions of Ardour. (or the closest possible)

/set_surface bank_size strip_types feedback fadermode
See below for an explanation of each parameter.

bank_size

Bank Size is the number of channel strips the controller supports without banking. Setting this to 0 turns banking off by setting the bank size to infinite.

Bank size can also be set with /set_surface/bank_size size.

strip_types

strip_types is an integer made up of bits. The easy way to deal with this is to think of strip_types items being worth a number and then adding all those numbers together for a value to send. Strip Types will determine what kind of strips will be included in bank. This would include: Audio, MIDI, busses, VCAs, Master, Monitor and hidden or selected strips.

Aside from setting the track types for the main mix assignments, using /set_surface/strip_types with more than one surface button will allow switching between modes for example: inputs only, busses only, selected only, hidden only, by having the buttons send values of: 3, 12, 256, 512. A full mix button might have a value 31.

While Master and Monitor are listed as possibilities, most surfaces will not use them. Using /master and /monitor makes more sense. However, in the case where there are no master or monitor fader strips on the surface, it may be necessary to include them in the banked strips.

Please see: Calculating Feedback and Strip-types Values.

Strip types can also be set with /set_surface/strip_types types.

feedback

Feedback is an integer made up of bits. The easy way to deal with this is to think of feedback items being worth a number and then adding all those numbers together for a value to send.

Please see: Calculating Feedback and Strip-types Values.

Feedback can also be set with /set_surface/feedback feedback.

gainmode

Gainmode is a an int that acts as a bool:

Gainmode applies only to feedback values. The controller can choose which gain math to use by choosing to use the /*/gain or /*/fader path to send to Ardour. This makes sure a controller that doesn't set up Ardour's OSC can still use either math. The gainmode for feedback also determines the path Ardour uses for feedback so that the feedback messages match the control messages.

Gain mode can also be set with /set_surface/gainmode gainmode.

Querying Ardour for information

The control Surface may wish to control the type a frequency of updates it receives. It can do this with querying commands. See: Querying Ardour with OSC.

List of OSC messages

Parameter types show how the value will be used. However, they may be sent as a different type if needed, see: Parameter Types in OSC.

Master or Global messages

Transport Control

/transport_stop
/transport_play
/toggle_roll
Toggles between play and stop
/set_transport_speed s
where s is a float ranging from -8.0f to 8.0f
/ffwd
/rewind
/goto_start
/goto_end
/jump_bars bars
Where bars is a float (+/-) of the number of bars to jump
/jump_seconds seconds
Where seconds is a float (+/-) of the number of seconds to jump
/add_marker
(adds marker to the current transport position)
/remove_marker
Removes marker at the current transport position (if there is one)
/mark_in
Marks the begining of a range at the current transport position
/mark_out
Marks the end of a range at the current transport position
/next_marker
/prev_marker
/locate spos roll
where spos is the target position in samples and roll is a bool/integer defining whether you want transport to be kept rolling or not
/loop_toggle
/loop_location start end
start is the beginning of a loop and end is the end of a loop both are integer frame positions.
/set_loop_range
Uses edit range as loop range
/set_session_range
Uses edit range as session range
/toggle_click
/midi_panic
Ardour will send an all notes off to all midi tracks
/cancel_all_solos
Cancel All Solos/PFLs/AFLs

Transport Information

/transport_frame
Ardour sends /transport_frame current_frame
/transport_speed
Ardour sends /transport_speed speed
/record_enabled
Ardour sends /record_enabled recordenable_status

Editing-related

/undo
/redo
/save_state
(this is the regular Session > Save operation)
/quick_snapshot_switch
Take a snapshot and switch to new version
/quick_snapshot_stay
Take a snapshot and keep working on this version
/fit_*_track(s)
Were * is one of 1, 2, 4, 8, 16, 32 or all. Fits this many tracks in editor window. (add s for more than 1)
/zoom_*
Zoom editor to include * where * is 100_ms, 1_sec, 10_sec, 1_min, 5_min, 10_min or to_session
/temporal_zoom_in
Zoom editor in to show less time
/temporal_zoom_out
Zoom editor out to show more time
/scroll_up_1_track
Scroll the editor pane up 1 track
/scroll_up_1_page
Scroll the editor pane up 1 page
/scroll_dn_1_track
Scroll the editor pane down 1 track
/scroll_dn_1_page
Scroll the editor pane down 1 page

Recording control

/toggle_punch_in
/toggle_punch_out
/set_punch_range
Uses edit range as punch range
/rec_enable_toggle
/stop_forget
Stop transport and delete/forget last take

Master and Monitor strip control

/master/gain dB
See gain in strips
/master/fader position
See fader in strips
/master/trimdB dB
see trimdb in strips
/master/pan_stereo_position position
See pan_stereo_position in strips
/master/mute yn
See mute in strips
/monitor/gain dB
See gain in strips
/monitor/fader position
See fader in strips

Track specific operations

For each of the following, ssid is the Surface Strip ID for the track

SSID has a different meaning than RID in Ardour version 4.7 and before. Effectively, banking is always being used and the SSID is generated on the fly. The SSID is the position of the strip within bank as an int 1 to bank size. There are no gaps as there have been in the past. Depending on the value of strip_types sent to Ardour, Master and Monitor, may be included in the list of SSIDs or not as set in /set_surface.

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. In this case the param should be a float even if an int is required below.

/bank_up
Change bank to the next higher bank.
/bank_down
Change bank to the next lower bank.
/strip/mute ssid mute_st
where mute_st is a bool/int representing the desired mute state of the track
/strip/solo ssid solo_st
where solo_st is a bool/int representing the desired solo state of the track
/strip/solo_iso ssid state
where state is a bool/int representing the desired solo isolate state of the track
/strip/solo_safe ssid state
where state is a bool/int representing the desired solo safe/lock state of the track
/strip/monitor_input ssid monitor_st
where monitor_st is a bool/int where 1 is forced input monitoring.
/strip/monitor_disk ssid monitor_st
where monitor_st is a bool/int where 1 is forced disk monitoring. When input and disk are both off, Auto monitoring is enabled.
/strip/recenable ssid rec_st
where rec_st is a bool/int representing the desired rec state of the track
/strip/record_safe ssid rec_st
where rec_st is a bool/int representing the desired record safe state of the track
/strip/polarity ssid invert
where invert is a bool/int representing the desired polarity of the track
/strip/gain ssid gain
where gain is a float ranging from -193 to 6 representing the desired gain of the track in dB.
/strip/fader ssid position
where position is a float ranging from 0 to 1 representing the fader control position.
/strip/trimdB ssid trim_db
where trim_db is a float ranging from -20 to 20 representing the desired trim of the track in dB.
/strip/pan_stereo_position ssid position
where position is a float ranging from 0 to 1 representing the desired pan position of the track
/strip/pan_stereo_width ssid width
where width is a float ranging from 0 to 1 representing the desired pan width of the track
/strip/send/gain ssid sendid send_gain
where sendid = nth_send, send_gain is a float ranging from -193 to +6 representing the desired gain in dB for the send
/strip/send/fader ssid sendid send_gain
where sendid = nth_send, send_gain is a float ranging from 0 to 1 representing the desired position for the send as a fader
/strip/send/enable ssid sendid state
where sendid = nth_send, state is 1 for enabled and 0 for disabled
/strip/list
see: Querying Ardour with OSC.
/strip/sends ssid
see: Querying Ardour with OSC.
/strip/receives ssid
see: Querying Ardour with OSC.
/strip/plugin/list ssid
see: Querying Ardour with OSC.
/strip/plugin/descriptor ssid
see: Querying Ardour with OSC.
/strip/plugin/reset ssid piid
where piid = nth Plugin, will reset all values to the plugin's original values
/strip/plugin/activate ssid piid
where piid = nth Plugin, will set the plugin's state to active
/strip/plugin/deactivate ssid piid
where piid = nth Plugin, will set the plugin's state to inactive
/strip/plugin/parameter ssid piid param value
where piid = nth Plugin, param = nth param, value is a float ranging from 0 to 1 representing the desired parameter value
/strip/name ssid name
where name is a string for the desired name of the track

Selected Strip Operations

New for Ardour 5, A whole set of operations that work on the selected or expanded strip.

Selected strip operations are complex enough for their own page. Please read: Selection Considerations in OSC. This is most important if more than one OSC surface is being used with Ardour.

There are two kinds of selection in OSC. GUI selection and local expansion. By default expansion follows selection.

/strip/select ssid y/n
Where y/n = 1 for select. Sets both GUI select and strip to expanded mode. (0 is ignored)
/strip/expand ssid y/n
Where y/n = 1 for expanded mode. Sets only local strip to Expanded. Setting to 0 resets the expansion to follow selection.
/select/expand y/n
Where y/n = 1 for expanded mode, 0 for Select mode.
/select/recenable y/n
Where y/n is 1 for enabled and 0 for disabled
/select/record_safe y/n
Where y/n is 1 for safe and 0 for unlocked
/select/mute y/n
Where y/n is 1 for enabled and 0 for disabled
/select/solo y/n
Where y/n is 1 for enabled and 0 for disabled
/select/solo_iso state
where state is a bool/int representing the desired solo isolate state of the track
/select/solo_safe state
where state is a bool/int representing the desired solo safe/lock state of the track
/select/monitor_input y/n
Where y/n is 1 for monitor from input and 0 for auto
/select/monitor_disk y/n
Where y/n is 1 for monitor from disk and 0 for auto
/select/polarity invert
where invert is a bool/int representing the desired polarity of the track
/select/gain gain
Where gain is a float ranging from -193 to 6 representing the desired gain of the track in dB.
/select/fader position
Where position is an float ranging from 0 to 1 representing the fader control position.
/select/trimdB trim_db
where trim_db is a float ranging from -20 to 20 representing the desired trim of the track in dB.
/select/pan_stereo_position position
where position is a float ranging from 0 to 1 representing the desired pan position of the track
/select/pan_stereo_width width
where width is a float ranging from 0 to 1 representing the desired pan width of the track
/select/pan_elevation_position position
where position is a float ranging from 0 to 1 representing the desired pan elevation of the track
/select/pan_frontback_position position
where position is a float ranging from 0 to 1 representing the desired front to back position of the track
/select/pan_lfe_control value
where value is a float ranging from 0 to 1 representing the desired LFE control value for the track
/select/send_gain", sendid send_gain
where sendid = nth_send, send_gain is a float ranging from -193 to +6 representing the desired gain in dB for the send
/select/send_fader", sendid send_gain
where sendid = nth_send, send_gain is a float ranging from 0 to 1 representing the desired position for the send as a fader
/select/send_enable", sendid state
where sendid = nth_send, state is 1 for enabled and 0 for disabled

Menu actions

Every single menu item in Ardour's GUI is accessible via OSC. There is a single common syntax to trigger the action as if it was selected with the mouse (or keyboard):

/access_action action_name

The list of actions shows all available values of action-name as of June 2016 for Ardour 5.0.pre0.1. You can get the current list at any time by running Ardour with the -b flag.