With the release of Windows 11 version 24H2, Microsoft has removed the Dolby Digital (AC-3) codec from the operating system. This change has led to audio playback issues in applications like Plex, which rely on this codec for surround sound. Users have reported experiencing silence during media playback that utilizes AC-3 audio tracks.

Background on AC-3 Codec

The AC-3 codec, also known as Dolby Digital, has been a standard for multichannel audio compression for over two decades. It enables efficient encoding of multiple audio channels, providing surround sound experiences in home theaters, DVDs, Blu-rays, and streaming services. Its widespread adoption has made it a cornerstone in audio playback across various platforms.

Microsoft's Decision to Remove AC-3 Support

Microsoft's decision to exclude the AC-3 codec from Windows 11 version 24H2 stems from their belief that device manufacturers will pre-install the necessary codec. In their support documentation, Microsoft states, "Many device manufacturers will pre-install an AC-3 codec." This approach assumes that hardware vendors will handle codec support, reducing the need for Microsoft to include it by default. (ghacks.net)

Implications for Plex Users

For users who perform a clean installation of Windows 11 24H2 or purchase new devices without the AC-3 codec pre-installed, applications like Plex that depend on this codec for audio playback encounter issues. Users have reported that media files with AC-3 audio tracks play without sound, rendering the content unwatchable. (forums.plex.tv)

Restoring AC-3 Support

To address this issue, users can manually restore AC-3 support by installing the necessary codec. One effective method involves using a third-party package that includes the Microsoft Dolby Digital Plus Encoder and Decoder. This package can be downloaded from GitHub and installed to re-enable AC-3 functionality. (neowin.net)

Optimizing Plex Audio Settings

After restoring the codec, it's advisable to adjust Plex's audio settings to ensure optimal playback:

  1. Open Plex and navigate to Settings.
  2. Select "Player" under "Plex for Windows."
  3. Click on "Show Advanced" at the top-right corner.
  4. In the "Audio Device" dropdown, select your actual audio device instead of "Auto."
  5. Choose the appropriate audio device type (e.g., Basic, Optical, or HDMI).
  6. Set the "Audio Channels" to match your speaker configuration.

These adjustments help Plex downmix multi-channel audio intelligently, ensuring a balanced and immersive audio experience. (neowin.net)

Alternative Solutions

If issues persist, consider using alternative media players that natively support AC-3 audio, such as VLC Media Player. VLC includes its own set of codecs, allowing it to handle AC-3 audio without relying on system-installed codecs. (pcworld.com)

Conclusion

The removal of the AC-3 codec from Windows 11 version 24H2 has introduced audio playback challenges for applications like Plex. By manually installing the necessary codec and configuring Plex's audio settings, users can restore functionality. Staying informed about such changes and proactively addressing them ensures a seamless media playback experience.

References