How to Stream Dolby Digital Audio in OBS Studio

This guide provides a straightforward walkthrough on how to configure OBS Studio to stream multi-channel Dolby Digital (AC-3) audio to compatible broadcast servers. You will learn how to set up your operating system’s audio configuration, adjust OBS channel settings, route your surround sound inputs, and configure the streaming encoder to deliver immersive multi-channel sound to your viewers.

Step 1: Configure Your Operating System Audio

Before configuring OBS Studio, your operating system must recognize your audio interface or playback device as a multi-channel system.

  1. Windows: Right-click the speaker icon in your system tray and select Sounds (or open Control Panel > Sound).
  2. Select your playback device, click Configure, and choose 5.1 Surround or 7.1 Surround.
  3. Complete the speaker configuration wizard to ensure all channels are active.
  4. macOS: Open Audio MIDI Setup, select your multi-channel output device, click Configure Speakers, and set it to 5.1 or 7.1 Rear Surround.

Step 2: Set OBS Studio Channels to Multi-Channel

Next, you need to change OBS Studio’s default stereo output to a surround sound configuration.

  1. Open OBS Studio.
  2. Go to Settings > Audio.
  3. Under the General section, locate the Channels dropdown.
  4. Change Stereo to 5.1 (or 7.1 depending on your audio setup).
  5. Click Apply and then restart OBS Studio if prompted to apply the channel changes.

Step 3: Map Your Audio Sources

With multi-channel audio enabled, you must route your audio inputs to the correct surround sound channels.

  1. In the Audio Mixer dock, click the gear icon (or three dots) next to any audio source and select Advanced Audio Properties.
  2. Locate the audio source you want to configure.
  3. Use the Balance slider to pan the audio, or use specialized surround-sound plugins if you need to map specific inputs (like microphones) to individual channels (e.g., the Center channel).
  4. In the Tracks matrix on the right, ensure your main stream track (usually Track 1) is selected for all sources you want to include in the multi-channel mix.

Step 4: Configure the Encoder for Dolby Digital (AC-3)

Standard RTMP streaming often restricts audio to stereo AAC. To stream Dolby Digital (AC-3), you must use either Enhanced RTMP (supported by YouTube) or SRT/RIST protocols, or utilize OBS’s Custom Output (FFmpeg).

Option A: Using Custom Output (FFmpeg) for SRT/RTMP

  1. Go to Settings > Output.
  2. Change the Output Mode dropdown to Advanced.
  3. Go to the Recording or Streaming tab (depending on your setup) and change the Type to Custom Output (FFmpeg).
  4. Set the Container Format to mpegts or flv (depending on server requirements).
  5. Set the Audio Encoder to ac3 (Dolby Digital) or eac3 (Dolby Digital Plus).
  6. Set the Audio Bitrate to at least 448 Kbps (for 5.1 audio) or 640 Kbps for optimal quality.

Option B: Using Enhanced RTMP / SRT

If your destination server supports Enhanced RTMP or SRT natively: 1. Go to Settings > Stream. 2. Set your Service to Custom and enter your server’s SRT or RTMP URL. 3. Go to Settings > Output > Streaming. 4. Set the Audio Encoder to an encoder that supports multi-channel output. While native OBS AAC can encode 5.1 audio, check with your broadcast server to ensure they accept multi-channel AAC or require transcoded AC-3.