Map MIDI Fader to OBS Webcam Brightness

Controlling your webcam’s lighting on the fly makes live streaming and video recording much more professional. This guide explains how to map an external MIDI fader or knob to smoothly adjust your webcam’s brightness in OBS Studio. By installing a dedicated OBS plugin and applying a color correction filter, you can gain tactile, real-time control over your video exposure without interrupting your broadcast.

Step 1: Install the obs-midi-mg Plugin

To connect MIDI signals to OBS Studio, you need a plugin that bridges the two. The most reliable and modern plugin for this is obs-midi-mg.

  1. Download the latest version of the obs-midi-mg plugin from the official OBS Resources forum or GitHub page.
  2. Run the installer or manually copy the files into your OBS Studio installation directory.
  3. Restart OBS Studio to load the plugin.

Step 2: Add a Color Correction Filter to Your Webcam

OBS cannot directly adjust a camera’s hardware brightness via midi, but it can adjust the brightness of the video feed using an internal filter.

  1. Open OBS Studio and locate your webcam in the Sources dock.
  2. Right-click the webcam source and select Filters.
  3. Click the + (plus) icon under the “Effect Filters” section and select Color Correction. Name it “Webcam Adjustments.”
  4. Locate the Brightness slider in the filter properties. Leave this open so you can watch it move during the mapping process.

Step 3: Map the MIDI Fader to the Brightness Filter

Now, configure the plugin to link your physical controller to the digital slider.

  1. In OBS, go to the top menu and select Tools > OBS MIDI MG Setup.
  2. Under the Devices tab, find your external MIDI controller, check the box to enable it, and set it as an input device.
  3. Go to the Bindings tab.
  4. Physical mapping: Move the physical fader or knob on your MIDI controller. The plugin will automatically detect the MIDI Control Change (CC) number. Click Add Binding for that detected input.
  5. In the binding action settings, configure the following:
    • Action Type: Source / Filter Value
    • Source: Select your webcam source.
    • Filter: Select “Webcam Adjustments” (the Color Correction filter you created).
    • Parameter: Select Brightness.

Step 4: Fine-Tune the Fader Sensitivity

By default, MIDI faders send values from 0 to 127. The OBS brightness filter operates on a scale of -1.0 to 1.0 (with 0.0 being neutral).

  1. In the binding configuration window, adjust the Min and Max target values.
  2. Set the target Min value to -0.5 and the Max value to 0.5 (or your preferred range). This prevents the fader from turning your screen entirely black or blindingly white at the extreme ends of the physical sweep.
  3. Move your physical fader to test the adjustment. The brightness slider in your webcam’s filter window should now move smoothly in sync with your hand.