Querying Ardour

In order to make a custom controller that knows what strips Ardour has, the controller needs to be able to query Ardour for that information. These set of commands are for smarter control surfaces That have the logic to figure out what to do with the information. These are not of value for mapped controllers like touchOSC and friends. The controller will need to send these queries to Ardour as often as it needs this information. It may well make sense to use regular feedback for things that need to be updated often such as position or metering. Here are the commands used to query Ardour: (added in Ardour 5.5)

/strip/list Ask for a list of strips
/strip/sends ssid Asks for a list of sends on the strip ssid
/strip/receives ssid Asks for a list of tracks that have sends to the strip ssid points to
/strip/plugin/list ssid Asks for a list of plug-ins for strip ssid.
/strip/plugin/descriptor ssid piid Asks for a list of descriptors for plug-in piid on strip ssid
/set_surface Ask for the current surface setting. Reply is in the same form as setting the surface would be.
/surface/list Print a list of known surfaces and Link Sets to the log window.

A list of strips

/strip/list asks Ardour for a list of strips that the current session has. Ardour replies with a message for each strip with the following information:

  • Strip type - One of:
    • AT - Audio Track
    • MT - MIDI Track
    • B - Audio Bus
    • MB - MIDI bus
    • FB - Foldback bus
    • V - VCA
  • Strip name
  • Number of inputs
  • Number of outputs
  • Muted
  • Soloed
  • Ssid (strip number)
  • Record enabled
After all the strip messages have been sent, one final message is sent with:
  • The text end_route_list
  • The session frame rate
  • The last frame number of the session
  • Monitor section present

The /set_surface should be set before this is called. That way The right set of strips will be sent in return (though the default is good for most uses) and feedback will start correctly.

If the surface is using /strip/list, the surface needs to know if the strips have changed. This would be true if a strip gets moved, created or deleted. When this happens Ardour sends /strip/list to the surfaces that have previously requested a /strip/list. This lets the surface know that its list of strips is no longer valid.

A bus will not have a record enable and so a bus message will have one less parameter than a track. It is the controllers responsibility to deal with this.

A list of sends

/strip/sends ssid asks Ardour for a list of sends for strip number ssid. The reply is sent back to the controller as one message with the following information:

  • Ssid that information is for
  • Each send's information:
    • The send's target bus ssid
    • The send's target bus name
    • The send id for this strip
    • The send gain as a fader position
    • The Send's enable state

The controller can tell how many sends there are from the number of parameters as each send has 5 parameters and there is one extra for ssid.

A list if tracks that send audio to a bus

/strip/receives ssid will return a list of tracks that have sends to the bus at the ssid. The reply will contain the following information for each track connected to this bus:

  • The ssid of the track sending
  • The name of the sending track
  • The id of the send at that track
  • It's gain in fader position
  • The send's enable state

A list of plug-ins for strip

/strip/plugin/list ssid will return a list of plug-ins that strip ssid has. The reply will contain the following information:

  • Ssid that information is for
  • Each plugin's information:
    • The plug-in's id
    • The plug-in's name

A list of a plug-in's parameters

/strip/plugin/descriptor ssid piid will return the plug-in parameters for ppid plug-in on the ssid strip. The reply will be sent as a number of messages, one for each parameter. Each message will contain the following information:

  • Ssid of the strip the plug-in is in
  • The plug-in id for the plug-in
  • The plug-in parameter id for the plug-in
  • The plug-in parameter's name
  • Information about that parameter:
    • A bitset of flags (see below)
    • Data type
    • Minimum value
    • Maximum value
    • The number of scale points
    • zero or more scale points of one value and one string each
    • The current parameter value

The plug-in parameter id is the position in the full list of plugin paramaters, but messages for controlling parameter values and their feedback use the position in the list of controllable parameters only (as specified by the controllable flag, see below).

After all the parameters have been sent this way, one final message" /strip/plugin/descriptor_end is sent with these parameters:

  • Ssid of the strip the plugin is in
  • The plug-in id for the plug-in

The flag bitset above has been defined as (from lsb):

  • 0—enumeration
  • 1—integer step
  • 2—logarithmic
  • 5—sample rate dependent
  • 6—toggled
  • 7—controllable
  • 8—hidden
Bits 3 and 4 are not used, they were max unbound and min unbound in previous versions and always zero.

While this seems complex, it is really not that bad. Minimum, maximum and value will in most cases give you all you need. For simpler access to plug-ins, the /select/plugin/ set of commands will handle most needs.

Obtaining a list of surfaces Ardour knows about

Ardour can work with more than one OSC control surface at a time. Sometimes it is useful to know the information stored about all surfaces. Sending /surface/list from any surface or selecting: Print surface information to Log window from the Debug dropdown in the OSC setup dialog, will list all the information Ardour uses to calculate the feedback it sends. The Log window can be opened from the menu with Window > Log. This would be useful information to include with any OSC related Bug report. The output is printed in this format:

Surface Output