manual/include/osc58-querying-ardour.html

<p>
  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)
</p>

<table class="dl">
  <tr><th><kbd class="osc">/strip/list</kbd></th>
  <td>Ask for a list of strips</td></tr>
  <tr><th><kbd class="osc">/strip/sends <em>ssid</em></kbd></th>
  <td>Asks for a list of sends on the strip <em>ssid</em></td></tr>
  <tr><th><kbd class="osc">/strip/receives <em>ssid</em></kbd></th>
  <td>Asks for a list of tracks that have sends to the strip <em>ssid</em> points to</td></tr>
  <tr><th><kbd class="osc">/strip/plugin/list <em>ssid</em></kbd></th>
  <td>Asks for a list of plug-ins for strip <em>ssid.</em></td></tr>
  <tr><th><kbd class="osc">/strip/plugin/descriptor <em>ssid</em> <em>piid</em></kbd></th>
  <td>Asks for a list of descriptors for plug-in <em>piid</em> on strip <em>ssid</em></td></tr>
  <tr><th><kbd class="osc">/set_surface</kbd></th>
  <td>Ask for the current surface setting. Reply is in the same form as setting the surface would be.</td></tr>
  <tr><th><kbd class="osc">/surface/list</kbd></th>
  <td>Print a list of known surfaces and Link Sets to the log window.</td></tr>
</table>

<h3>A list of strips</h3>

<p>
  <code>/strip/list</code> asks Ardour for a list of strips that the
  current session has. Ardour replies with a message for each
  strip with the following information:
  <ul>
    <li>Strip type - One of:</li>
    <ul>
		<li>AT - Audio Track</li>
		<li>MT - MIDI Track</li>
		<li>B - Audio Bus</li>
		<li>MB - MIDI bus</li>
		<li>AX - Aux bus</li>
		<li>V - VCA</li>
    </ul>
    <li>Strip name</li>
    <li>Number of inputs</li>
    <li>Number of outputs</li>
    <li>Muted</li>
    <li>Soloed</li>
    <li>Ssid (strip number)</li>
    <li>Record enabled</li>
  </ul>
  After all the strip messages have been sent, one final message is
  sent with:
  <ul>
    <li>The text <code>end_route_list</code></li>
    <li>The session frame rate</li>
    <li>The last frame number of the session</li>
    <li>Monitor section present</li>
  </ul>
</p>
<p class="note">
	The <code>/set_surface</code> 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.
</p>
<p>
  If the surface is using <code>/strip/list</code>, 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 <code>/strip/list</code> to the surfaces
  that have previously requested a <code>/strip/list</code>. This lets the
  surface know that its list of strips is no longer valid.
</p>
<p class="note">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.
</p>

<h3>A list of sends</h3>
<p>
  <code>/strip/sends <em>ssid</em></code> 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:
  <ul>
    <li>Ssid that information is for</li>
    <li>Each send's information:</li>
    <ul>
      <li>The send's target bus ssid</li>
      <li>The send's target bus name</li>
      <li>The send id for this strip</li>
      <li>The send gain as a fader position</li>
      <li>The Send's enable state</li>
    </ul>
  </ul>
</p>
<p>
  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.
</p>

<h3>A list if tracks that send audio to a bus</h3>
<p>
  <code>/strip/receives <em>ssid</em></code> 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:
  <ul>
    <li>The ssid of the track sending</li>
    <li>The name of the sending track</li>
    <li>The id of the send at that track</li>
    <li>It's gain in fader position</li>
    <li>The send's enable state</li>
  </ul>
</p>

<h3>A list of plug-ins for strip</h3>
<p>
  <code>/strip/plugin/list <em>ssid</em></code> will return a list of
  plug-ins that strip ssid has. The reply will contain the following
  information:
  <ul>
    <li>Ssid that information is for</li>
    <li>Each plugin's information:</li>
    <ul>
      <li>The plug-in's id</li>
      <li>The plug-in's name</li>
    </ul>
  </ul>
</p>

<h3>A list of a plug-in's parameters</h3>
<p>
  <code>/strip/plugin/descriptor <em>ssid</em> <em>piid</em></code> 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:
  <ul>
    <li>Ssid of the strip the plug-in is in</li>
    <li>The plug-in id for the plug-in</li>
    <li>The plug-in parameter id for the plug-in</li>
    <li>The plug-in parameter's name</li>
    <li>Information about that parameter:</li>
    <ul>
      <li>A bitset of flags (see below)</li>
      <li>Data type</li>
      <li>Minimum value</li>
      <li>Maximum value</li>
      <li>The number of scale points</li>
      <li>zero or more scale points of one value and one string each</li>
      <li>The current parameter value</li>
    </ul>
  </ul>
</p>
<p>
	After all the parameters have been sent this way, one final message"
	<code>/strip/plugin/descriptor_end</code> is sent with these parameters:
	<ul>
	  <li>Ssid of the strip the plugin is in</li>
	  <li>The plug-in id for the plug-in</li>
	</ul>
</p>
<p>
  The flag bitset above has been defined as (from lsb):
  <ul>
    <li>0&mdash;enumeration</li>
    <li>1&mdash;integer step</li>
    <li>2&mdash;logarithmic</li>
    <li>5&mdash;sample rate dependent</li>
    <li>6&mdash;toggled</li>
    <li>7&mdash;controllable</li>
    <li>8&mdash;hidden</li>
  </ul>
  Bits 3 and 4 are not used, they were max unbound and min unbound in
  previous versions and always zero.
</p>
<p>
	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.
</p>
<h3>Obtaining a list of surfaces Ardour knows about</h3>
<p>
	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 <code>/surface/list</code> from any surface or selecting:
	<kbd class="menu">Print surface information to Log window</kbd> from
	the <kbd class="menu">Debug</kbd> 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
	<kbd class="option">Window &gt; Log</kbd>.
	This would be useful information to include with any OSC
	related Bug report. The output is printed in this format:
</p>
<p>
<img alt="Surface Output"
     src="/images/osc-surface-log.png">
</p>