How to Stream Audio Only from OBS to Icecast

This guide provides a step-by-step walkthrough on how to configure OBS Studio to broadcast an audio-only stream to an Icecast or Shoutcast server. While OBS Studio is primarily designed for video streaming, you can use its built-in FFmpeg output capabilities to transmit high-quality, low-bandwidth audio feeds for internet radio, podcasts, or live music without needing external encoding software.

Step 1: Optimize OBS for Audio-Only (Reduce CPU Usage)

Because OBS Studio is a video encoder at its core, you should minimize video processing to save system resources.

1. Open OBS Studio and go to Settings -> Video.
2. Set the Base (Canvas) Resolution and Output (Scaled) Resolution to the lowest possible values (e.g., 640x360).
3. Set the Common FPS Values to 10 or 15. This significantly reduces CPU and GPU usage.
4. Go to the Audio tab and configure your Global Audio Devices (e.g., Desktop Audio, Mic/Auxiliary Audio) to capture the sound you want to stream.

Step 2: Configure the FFmpeg Output Settings

To bypass the standard video RTMP stream and target an Icecast or Shoutcast server, you must use the Custom FFmpeg output mode.

1. Go to Settings -> Output.
2. Change the Output Mode dropdown at the top from Simple to Advanced.
3. Click on the Recording tab (we will use this tab to stream instead of the “Stream” tab).
4. Change the Type to Custom Output (FFmpeg).
5. Set FFmpeg Output Type to Output to URL.

Step 3: Enter Your Server Credentials

In the File path or URL field, you need to enter the connection string for your destination server.

• For Icecast: Use the following format: icecast://source:password@yourserver.com:8000/mountpoint (Replace password with your Icecast source password, yourserver.com with your server’s IP or domain, 8000 with your port, and /mountpoint with your designated mount point, e.g., /live or /stream.mp3).

• For Shoutcast: Use the following format: shoutcast://source:password@yourserver.com:8000

Step 4: Configure Audio and Video Encoding Settings

To ensure the stream sends only audio, you must disable video encoding and select the appropriate audio codec.

1. Set Container Format to ogg (for Ogg Vorbis/Opus) or mp3 (for MP3 streams).
2. Set Video Bitrate to 0.
3. Set Video Encoder to none (disable video).
4. Set Audio Bitrate to your preferred quality (e.g., 128 Kbps or 320 Kbps).
5. Set Audio Encoder to:
   • libmp3lame for an MP3 stream.
   • libvorbis or opus for an Ogg stream.
   • aac for an AAC stream.

Click Apply and then OK to save your settings.

Step 5: Start the Broadcast

1. Ensure your audio sources in the Audio Mixer dock are active and levels are green/yellow.
2. Instead of clicking “Start Streaming” in the main OBS control panel, click Start Recording.
3. Because you configured the Recording tab to output to a URL, OBS will now connect directly to your Icecast or Shoutcast server and begin broadcasting your audio feed.
4. To stop the broadcast, click Stop Recording.