Add heart rate to your stream with OBS and Cardia

In this tutorial we are going to look how to add heart rate to your stream with OBS and Cardia. Cardia is first open source Heart Rate Monitor designed for gaming and broadcasting: it will display your current heart rate and generates a simulated ECG tracing. With the upcoming OBS version you can stream to Twitch and Mixer. In this tutorial im going to use Polar H7 Bluetooth Heart Rate sensor.

Things you need

  • Heart Rate sensor which is Bluetooth Smart HRP compliant or Zephyr HxM or Contec CMS50.
  • Computer with Bluetooth dongle
  • Cardia and OBS installed

Pairing your bluetooth heart rate sensor with computer

1.Open Start menu, write bluetooth and select Bluetooth and other devices settings.

2. Add Bluetooth or other device.

3. Select Bluetooth.

4. Select your heart rate sensor. If you cant see your bluetooth heart rate sensor, make sure that it isn’t connected to your phone or in other devices.

Installing Cardia and adding it to OBS

1.Download latest version of Cardia from this link – https://github.com/uwburn/cardia/releases . You don’t have to install it, only extract and start.

2. Go to Device and select Bluetooth Smart HRP if you have bluetooth heart rate sensor. After that you can open Configuration.

3. Program should automatically find your heart rate sensor. After you are sure that your device is found and connected to application. You can close the configuration window and hit Start button from right bottom.

4. You can make Cardia borderless by right clicking the application and clicking Shrink.

Shrink Cardia application

5. Open OBS and add new Windows Capture to your scene.

Add Windows Capture to OBS Scene


6. Select Cardia.exe from Window list. You cannot use “Windows title must match” property on Window Match Priority selection, because the title of Cardia is changing all the time, so you have to use the “Find window of same executable” option, after that you can click Ok.

OBS Windows Capture properties

7. And you are ready to go. You can place your heart rate as you want in your scene and resize it like you want. If you want to remove the black background, continue to next step.

Changing heart rate monitor background to transparent

If you want, you can remove the black background of Cardia heart rate monitor and make it to transparent.

1.Add filters to your heart rate source.

Add filters to scene in OBS

2. Select Chroma Key filter.

Adding Chroma Key filter in OBS

3. Change Key Color Type to Custom, Key Color to #000000, and play with Similarity and Smoothness sliders to get the look you want.

Chroma Key filter settings in OBS

4. If you have any questions, please write a comment.

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