User Guide: 64 Sources with open-stage-control and ICST AmbiEncoder_64

Level: Intermediate | Audience: Composer, technician, student, live-electronics user.

This user guide describes the current XYZ session for open-stage-control in combination with the ICST AmbiEncoder_64.

Download:

• 64-source-points-tablet-xyz.session.json

The session controls the sources in Cartesian XYZ and is built for working directly with the plugin radar:

• top = front
• right = right
• +X points right
• +Y points forward

The left fader controls Z (height, -1..1) instead of Distance. Pad and plugin radar therefore correspond directly in this session.

The session sends ICST-compatible OSC to the AmbiEncoder_64:

• /icst/ambi/sourceindex/xyz [Index] [X] [Y] [Z]
• /icst/ambi/sourceindex/gain [Index] [Gain]

The source index is 1-based. The gain fader displays dB; a linear factor is sent (see 7. Troubleshooting).

1. Prepare REAPER and the AmbiEncoder_64

1. Open your REAPER project or create a new one.
2. Create a track for the encoder and insert ICST AmbiEncoder_64 as an FX.
3. Make sure the track has enough channels (Track Routing > Track channels); otherwise the 64-source encoder will not work fully.
4. Open the plugin window of the AmbiEncoder_64.
5. Open the OSC section in the plugin and enable OSC In (Receive).
6. Note the receive port set there. The usual default in the ICST tutorials is 50001, but what counts is the port actually set in the plugin.
7. Keep the plugin window open for the first test so you can see whether the sources move.

2. Start open-stage-control

1. Start open-stage-control. The launcher opens first.

2. In the launcher, enter the OSC target under send:

   • REAPER on the same computer: 127.0.0.1:50001
   • REAPER on another computer: IP-of-the-REAPER-computer:50001
   • If necessary: use the port from part 1

3. Under Port, enter the HTTP port for the user interface, for example 8080.

4. Click Start. The empty interface opens in the browser or app window.

5. Load the session via Menu > Session > Open and choose 64-source-points-tablet-xyz.session.json. Alternatively, drag and drop the file into the window.

3. Connect the tablet

1. Connect the tablet to the same network as the computer running open-stage-control.

2. Find out the IP address of that computer.

   • macOS: System Settings > Network
   • or in Terminal: ipconfig getifaddr en0

3. On the tablet, open a browser and go to http://IP-of-the-computer:8080. If you set a different HTTP port, use that one.

4. The interface appears in the browser. For full screen on the iPad: add the page via Share > Add to Home Screen and start it from there.

5. Important: the tablet only talks to open-stage-control. The OSC to REAPER is sent by the computer running open-stage-control.

4. First function test

1. In the interface, go to the Select + Focus tab.

2. Press the blue button Alle 64 senden (Sync) (send all 64) at the bottom right.

   This button sends all positions and gains to the plugin once. Afterwards, interface and plugin show the same state. This is the first step after every start of open-stage-control.

3. Tap S1 in the grid on the left. The button turns orange, and Source 1 appears on the right.

4. Move the point in the large XY pad.

5. Look at the plugin window of the AmbiEncoder_64: source 1 must move along.

6. Then move the Z and Gain dB faders and check the response in the plugin.

7. If that works, try a bank tab such as S1-8 and move several points there at the same time.

Note on the display: in this session the pad is a top view in XYZ. It therefore corresponds directly to the plugin radar.

If nothing moves in step 4, see 7. Troubleshooting.

5. Operation overview

Tab Select + Focus

1. Select a source: tap the desired button in the 8x8 grid on the left. The active source is marked orange.
2. Set the position: move the point in the large pad on the right. The session works in Cartesian X/Y.
3. Set Z (-1..1) and Gain (dB) (-60..+12) with the two horizontal faders. Both faders have a number field for precise input.
4. Rename: tap the text field at the top right, type the name and confirm. The name appears on the grid button immediately. Without a custom name the button shows S1 to S64.

Bank tabs S1-8 to S57-64

1. Open the tab of the desired group.
2. In the large multi-XY pad you can move single or several points at the same time (multitouch).
3. Each point sends its XYZ message immediately.
4. The sources are evenly arranged in the pad, so you can see at once which point belongs to which source.

6. Saving

1. Positions and names change during the session. To keep the state, choose Menu > Session > Save or Save As in open-stage-control, ideally under a new name.
2. The settings of the AmbiEncoder_64, including the last received positions, are saved as usual with the REAPER project (Cmd+S).

7. Troubleshooting

Nothing arrives in the plugin

1. Is OSC In really enabled in the AmbiEncoder_64?
2. Do host and port in the send settings of open-stage-control exactly match the plugin?
3. Is a firewall blocking incoming UDP packets on the REAPER computer?
4. Is a second instance of open-stage-control without a send target running by mistake?

The tablet cannot find the interface

1. Are tablet and computer on the same network?
2. Do IP address and HTTP port in the browser address match?
3. Use http://, not https://.
4. Allow incoming connections for open-stage-control in the firewall.

The wrong source moves

1. The source index is 1-based: S1 in the interface corresponds to source 1 in the plugin.
2. Check that the desired source is actually marked orange in the grid.

Movements stutter over the network

1. Check the Wi-Fi quality.
2. Connect the computer by cable if needed.
3. Take other devices with heavy traffic off the Wi-Fi.

Plugin and interface show different positions

1. open-stage-control sends nothing by itself at startup. Press Alle 64 senden (Sync) once after every start.

Plugin reports Unknown OSC message received

1. An outdated copy of the session is running, for example from ~/Downloads.
2. Use only the current session file from this page.
3. Restart open-stage-control after changing the file. Running sessions do not reload changes automatically.

Plugin reports Malformed OSC message

1. The source index must arrive as an integer, not as a float.
2. The session types it correctly in its scripts as {type: 'i'}.

Gain fader moves, but the plugin jumps to -88 dB

1. This plugin build expects gain as a linear factor, not in dB.
2. The session therefore converts when sending: the fader shows dB (-60..+12), and 10^(dB/20) is sent.
3. 0 dB corresponds to a factor of 1.0.
4. Confirmed on 18.08.2026.

Notes for future session changes in open-stage-control v1.29

1. Script code belongs in the widget property onValue, not in script.
2. The shared-state object is called globals, not global.
3. send() without a target argument sends to the launcher default. send(false, ...) is invalid.
4. Every widget, including panels and tabs, needs "bypass": true; otherwise it sends its raw value.
5. The console at the bottom of the open-stage-control window shows script errors. Check there first.

8. This session

64-source-points-tablet-xyz.session.json works in stage coordinates (XYZ). The pad is a top view like the plugin radar, and the two correspond directly. This page describes only this current XYZ version.

Sources

• ICST AmbiEncoder – OSC syntax
• OSC
• Motion Map Setup