manual/include/osc58-feedback.html

<p>
  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
  the DAW fader will jump to where the controller fader is. Likewise,
  the buttons on each strip need to know what their value is so they can
  light their LED correctly. Transport controls should let you know if
  they are active too. This is what feedback is all about.
</p>
<p>
  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:
</p>

<table class="dl">
  <tr><th><kbd class="osc">/transport_stop</kbd></th>
  <td></td></tr>
</table>
<p>can be used also in the form:</p>

<table class="dl">
  <tr><th><kbd class="osc">/transport_stop <em>press</em></kbd></th>
  <td>where <em>press</em> is an int/bool indicating if the button is pressed or not.</td></tr>
</table>

<p>
  The feedback does not have the same meaning as the control message.
  Where the button release sent to Ardour will be ignored and has no
  meaning. Both states have meaning in feedback to the controller.
  The feedback will be:
</p>

<table class="dl">
  <tr><th><kbd class="osc">/transport_stop <em>state</em></kbd></th>
  <td>where <em>state</em> is an int/bool indicating if the transport is stopped or not.</td></tr>
</table>
<p>
  With feedback turned on, OSC control commands that try to change a
  control that does not exist will get feedback that resets that control
  to off. For example, sending a /strip/recenable to a buss will not work
  and Ardour will try to turn the controller LED off in that case. Also
  note that Pan operation may be limited by pan width in some cases.
  That is with pan width at 100% (or -100%) there is no pan position
  movement available.
</p>
<p>
  It may come as a surprise, but feedback often generates more network
  traffic than control itself does. Some things are more obvious like
  head position or meters. But even a simple button push like transport
  start sends not only a signal to turn on the play LED, but also one to
  turn off the stop LED, the Rewind LED, the Fast Forward LED and the
  Loop LED. That is still minor, think instead of a surface refresh
  such as happens when the surface is first connected and then most of
  that happens every time the fader strips are banked. This is why
  feedback is enabled in sections so that as little feedback as is
  actually needed is sent. This is also a consideration if the surface
  is connected via wifi.
</p>
<h2>List of OSC feedback messages</h2>

<h3>Feedback only</h3>
<p>
  These messages are feedback only. They are sent as status from Ardour
  and some of them may be enabled separately from other feedback. See:
  <a href="@@osc58-feedback-and-strip-types-values">
  Calculating Feedback and Strip-types Values.</a>
</p>
<p class="note">
  See strip section below for info about ssid and wrapping it into the
  path. Also /master and /monitor support what the /strip does.
</p>
<p>
  In the case where Gainmode is set to position, the track name will
  show the dB value while values are changing.
</p>
<table class="dl">
  <tr><th><kbd class="osc">/strip/name <em>ssid</em> <em>track_name</em></kbd></th>
  <td>where <em>track_name</em> is a string representing the name of the track</td></tr>
  <tr><th><kbd class="osc">/session_name <em>session_name</em></kbd></th>
  <td>where <em>session_name</em> is a string representing the name of the session</td></tr>
  <tr><th><kbd class="osc">/strip/meter <em>ssid</em> <em>meter</em></kbd></th>
  <td>where <em>meter</em> is a value repesenting the current audio level.
  (the exact math used is determined by the feedback bits set)</td></tr>
  <tr><th><kbd class="osc">/strip/signal <em>ssid</em> <em>signal</em></kbd></th>
  <td>where <em>signal</em> is a float indicating the instantaneous
  audio level is -40dB or higher.</td></tr>
  <tr><th><kbd class="osc">/position/smpte <em>time</em></kbd></th>
  <td>where <em>time</em> is a string with the current play head time. Seconds as per smpte.</td></tr>
  <tr><th><kbd class="osc">/position/bbt <em>beat</em></kbd></th>
  <td>where <em>beat</em> is a string with the current play head bar/beat.</td></tr>
  <tr><th><kbd class="osc">/position/time <em>time</em></kbd></th>
  <td>where <em>time</em> is a string with the current play head time. Seconds are in milliseconds</td></tr>
  <tr><th><kbd class="osc">/position/samples <em>samples</em></kbd></th>
  <td>where <em>samples</em> is a string with the current play head position in samples.</td></tr>
  <tr><th><kbd class="osc">/heartbeat <em>LED</em></kbd></th>
  <td>where <em>LED</em> is a float that cycles 1/0 at 1 second intervals.</td></tr>
  <tr><th><kbd class="osc">/record_tally <em>state</em></kbd></th>
  <td>Some record enable is true or "ready to record". For a "Recording" sign at studio door.</td></tr>
</table>

<h3>Transport Control</h3>
<table class="dl">
  <tr><th><kbd class="osc">/transport_stop <em>state</em></kbd></th>
  <td><em>state</em> is true when transport is stopped</td></tr>
  <tr><th><kbd class="osc">/transport_play <em>state</em></kbd></th>
  <td><em>state</em> is true when transport speed is 1.0</td></tr>
  <tr><th><kbd class="osc">/ffwd <em>state</em></kbd></th>
  <td><em>state</em> is true when transport is moving forward but not at speed 1.0</td></tr>
  <tr><th><kbd class="osc">/rewind <em>state</em></kbd></th>
  <td><em>state</em> is true when transport speed is less than 0.0</td></tr>
  <tr><th><kbd class="osc">/loop_toggle <em>state</em></kbd></th>
  <td><em>state</em> is true when loop mode is true</td></tr>
  <tr><th><kbd class="osc">/cancel_all_solos <em>state</em></kbd></th>
  <td>Where <em>state</em> true indicates there are active solos that can be canceled.</td></tr>
</table>

<h3>Recording control</h3>
<table class="dl">
  <!--dt><kbd class="osc">/toggle_punch_in</kbd></th>
  <td></td></tr>
  <tr><th><kbd class="osc">/toggle_punch_out</kbd></th>
  <td></dd-->
  <tr><th><kbd class="osc">/rec_enable_toggle <em>state</em></kbd></th>
  <td>Master record enabled.</td></tr>
</table>

<h3>Master and monitor strips</h3>
<p>
  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:
</p>
<table class="dl">
  <tr><th><kbd class="osc">/master/gain <em>dB</em></kbd></th>
  <td>where <em>dB</em> is a float ranging from -193 to +6 representing the actual gain of master in dB</td></tr>
  <tr><th><kbd class="osc">/master/fader  <em>position</em></kbd></th>
  <td>where <em>position</em> is an int ranging from 0 to 1023 representing the fader control position</td></tr>
  <tr><th><kbd class="osc">/master/trimdB <em>dB</em></kbd></th>
  <td>where <em>dB</em> is a float ranging from -20 to +20 representing the actual trim for master in dB</td></tr>
  <tr><th><kbd class="osc">/master/pan_stereo_position <em>position</em></kbd></th>
  <td>where <em>position</em> is a float ranging from 0 to 1 representing the actual pan position for master</td></tr>
  <tr><th><kbd class="osc">/master/mute  <em>yn</em></kbd></th>
  <td>where <em>yn</em> is a bool/int representing the actual mute state of the Master strip</td></tr>
  <tr><th><kbd class="osc">/monitor/gain <em>dB</em></kbd></th>
  <td>where <em>dB</em> is a float ranging from -193 to 6 representing the actual gain of monitor in dB</td></tr>
  <tr><th><kbd class="osc">/monitor/fader  <em>position</em></kbd></th>
  <td>where <em>position</em> is an int ranging from 0 to 1023 representing the fader control position</td></tr>
</table>

<h3>Track specific operations</h3>
<p>
  For each of the following, <em>ssid</em> is the surface strip ID for the track
</p>
<p class="note">
  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 <em>state</em>
  command. See <a
  href="/using-control-surfaces/controlling-ardour-with-osc/calculating-feedback-and-strip-types-values/">
  Calculating Feedback and Strip-types Values.</a>
</p>

<table class="dl">
  <tr><th><kbd class="osc">/bank_up <em>LED</em></kbd></th>
  <td>where <em>LED</em> is a bool that indicates another bank_up operation is possible.</td></tr>
  <tr><th><kbd class="osc">/bank_down <em>LED</em></kbd></th>
  <td>where <em>LED</em> is a bool that indicates another bank_down operation is possible.</td></tr>
  <tr><th><kbd class="osc">/strip/name <em>ssid</em> <em>track_name</em></kbd></th>
  <td>where <em>track_name</em> is a string representing the name of the track
  (note there is no coresponding command to set the track name)</td></tr>
  <tr><th><kbd class="osc">/strip/mute <em>ssid</em> <em>mute_st</em></kbd></th>
  <td>where <em>mute_st</em> is a bool/int representing the actual mute state of the track</td></tr>
  <tr><th><kbd class="osc">/strip/solo <em>ssid</em> <em>solo_st</em></kbd></th>
  <td>where <em>solo_st</em> is a bool/int representing the actual solo state of the track</td></tr>
  <tr><th><kbd class="osc">/strip/monitor_input <em>ssid</em> <em>monitor_st</em></kbd></th>
  <td>where <em>monitor_st</em> is a bool/int. True/1 meaning the track is force to monitor input</td></tr>
  <tr><th><kbd class="osc">/strip/monitor_disk <em>ssid</em> <em>monitor_st</em></kbd></th>
  <td>where <em>monitor_st</em> 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.</td></tr>
  <tr><th><kbd class="osc">/strip/recenable <em>ssid</em> <em>rec_st</em></kbd></th>
  <td>where <em>rec_st</em> is a bool/int representing the actual rec state of the track</td></tr>
  <tr><th><kbd class="osc">/strip/record_safe <em>ssid</em> <em>rec_st</em></kbd></th>
  <td>where <em>rec_st</em> is a bool/int representing the actual record safe state of the track</td></tr>
  <tr><th><kbd class="osc">/strip/gain <em>ssid</em> <em>gain</em></kbd></th>
  <td>where <em>gain</em> is a float ranging from -193 to 6 representing the actual gain of the track in dB.</td></tr>
  <tr><th><kbd class="osc">/strip/fader <em>ssid</em>  <em>position</em></kbd></th>
  <td>where <em>position</em> is an float ranging from 0 to 1 representing the actual fader position of the track.</td></tr>
  <tr><th><kbd class="osc">/strip/trimdB <em>ssid</em>  <em>trim_db</em></kbd></th>
  <td>where <em>trim_db</em> is a float ranging from -20 to 20 representing the actual trim of the track in dB.</td></tr>
  <tr><th><kbd class="osc">/strip/pan_stereo_position <em>ssid</em> <em>position</em></kbd></th>
  <td>where <em>position</em> is a float ranging from 0 to 1 representing the actual pan position of the track</td></tr>
</table>
<h3>Selection Operations</h3>
<p>
  Selection feedback is the same as for strips, only the path changes
  from <em>/strip</em> to <em>/select</em> and there is no <em>ssid</em>.
  there are some extra feedback and commands that will be listed here.
</p>
<table class="dl">
  <tr><th><kbd class="osc">/select/n_inputs <em>number</em></kbd></th>
  <td>where <em>number</em> number of inputs for this strip</td></tr>
  <tr><th><kbd class="osc">/select/n_outputs <em>number</em></kbd></th>
  <td>where <em>number</em> number of outputs for this strip</td></tr>
  <tr><th><kbd class="osc">/select/comment <em>text</em></kbd></th>
  <td>where <em>text</em> is the strip comment</td></tr>
  <tr><th><kbd class="osc">/select/solo_iso <em>state</em></kbd></th>
  <td>where <em>state</em> is a bool/int representing the Actual solo isolate state of the track</td></tr>
  <tr><th><kbd class="osc">/select/solo_safe <em>state</em></kbd></th>
  <td>where <em>state</em> is a bool/int representing the actual solo safe/lock state of the track</td></tr>
  <tr><th><kbd class="osc">/select/polarity <em>invert</em></kbd></th>
  <td>where <em>invert</em> is a bool/int representing the actual polarity of the track</td></tr>
  <tr><th><kbd class="osc">/select/pan_stereo_width <em>width</em></kbd></th>
  <td>where <em>width</em> is a float ranging from 0 to 1 representing the actual pan width of the track</td></tr>
  <tr><th><kbd class="osc">/select/send_gain", <em>sendid</em> <em>send_gain</em></kbd></th>
  <td>where <em>sendid</em> = nth_send, <em>send_gain</em>is a float
  ranging from -193 to +6 representing the actual gain in dB for the send</td></tr>
  <tr><th><kbd class="osc">/select/send_fader", <em>sendid</em> <em>send_gain</em></kbd></th>
  <td>where <em>sendid</em> = nth_send, <em>send_gain</em>is a float
  ranging from 0 to 1 representing the actual position for the send as a fader</td></tr>
  <tr><th><kbd class="osc">/select/send_name <em>sendid</em> <em>send_name</em></kbd></th>
  <td>where <em>send_name</em> is a string representing the name of the buss
  this send goes to.</td></tr>
</table>
<h3>Menu actions</h3>
<p>
  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.
</p>