# Set up the source stream using OBS

Open Broadcaster Software (OBS) Studio can send a camera, capture device, or test source to an MK.IO live event over RTMP. Configure the source, encoder, and MK.IO input URL before you start streaming.

## Install OBS Studio

1. Download and install OBS for your operating system on the [Open Broadcaster Software website](https://obsproject.com/).
2. Start the application. OBS starts with a default scene but with no inputs selected.

## Add a video source

1. From the **Sources** panel, select the add icon.
2. Select **Video Capture Device**.
3. Select **Add Existing**, then select **OK**.
4. From the **Device** list, select the video input for the broadcast.
5. Leave the remaining settings unchanged and select **OK**.

The input appears in the **Sources** panel and the video appears in the preview.

### Add a browser test source

If you do not have a capture device ready, you can use a browser source for a first test:

1. Select the add icon under **Sources**.
2. Select **Browser**.
3. Name the source `Clock` and enter `https://vclock.com` as its URL.

If the source shows a cookie-consent prompt, right-click the browser source, select **Interact**, and accept the prompt.

## Add an audio source

1. From the **Sources** panel, select the add icon.
2. Select **Audio Input Capture**.
3. Select **Add Existing**, then select **OK**.
4. From the **Device** list, select the audio capture device for the broadcast.
5. Leave the remaining settings unchanged and select **OK**.

The audio capture device appears in the audio mixer.

## Set up streaming and advanced encoding settings

Before continuing, [start the live event](/mkio/how-to/live-streaming/set-up-a-live-streaming-event#start-streaming) and copy its **Input URL**.

1. Select **Settings** in the **Controls** panel.
2. Select **Stream** in the left menu.
3. From **Service**, select **Show all**, then select **Custom**.
4. In **Server**, paste the RTMP input URL without the final `/stream` suffix.
5. In **Stream Key**, enter a valid stream name, such as `stream`.
6. Select **Output** in the left menu.
7. Set **Output Mode** to **Advanced**.
8. On the **Streaming** tab, select the encoder settings for the computer's processor and capabilities:
   - Set **Audio Encoder** to FFmpeg AAC or CoreAudio AAC.
   - Set **Video Encoder** to x264.
   - Use constant bitrate (CBR) rate control.
   - Match **Keyframe interval** to the **Input key frame interval** configured in [MK.IO](/mkio/how-to/live-streaming/set-up-a-live-streaming-event#configure-a-live-event).

## Set audio settings

1. Select **Output** > **Audio**.
2. Set **Audio Bitrate** for the source.
3. Set **Sample Rate** to 48 kHz.

## Set video settings

1. Select **Output** > **Video**.
2. Set **Output (Scaled) Resolution** to **1920x1080**.
3. Set **Common FPS Values** for the source.
4. Select **OK**.

## Start streaming

The combined video and audio bitrate must not exceed the live event's bandwidth limit.

1. In the **Controls** panel, select **Start Streaming**.
2. Return to the live event in MK.IO, then select **Apply**.
3. Confirm that the source appears in the preview.
4. Copy the playback URLs for use in a compatible player or application.

## Check the OBS status

Use the OBS status bar to check the source while it is running:

- **Bitrate** shows how much data OBS sends each second. It should remain stable.
- **Dropped frames** should remain at 0 percent. A rising value indicates a network or processor problem.
- **FPS** shows the frame rate sent by OBS.
- **CPU usage** should remain below 60 percent. Usage near 90 percent can affect the output quality.

![OBS status bar showing stream bitrate, dropped frames, frame rate, and CPU usage](/images/obs-example.png)