How to restore Dolby Digital (AC-3) support in Windows 11 24H2

With the release of Windows 11 24H2 last year, and the super slow roll out of it to devices, one thing you may have missed, and also somewhat slipped under the radar, is that Microsoft have removed the AC-3 (Dolby Digital) codec, explaining in the support document that "many device manufacturers will pre-install an AC-3 codec". However, if you upgrade from an earlier edition on Windows 11 to 24H2, that codec will remain on the system.

For those that opted to clean install Windows 24H2, or bought a new computer with it preinstalled without the codec, luckily there is a third party fix to restore AC-3 support, as discovered in multiple topics on Reddit, my guide is inspired by this post. Apps like Plex might have an issue where AC-3 is required and no sound will be heard. This can be restored with the AnWave 2024 Split Feature Release, found on GitHub.

Installation instructions

1. Download the Microsoft.Dolby.Digital.Atmos.Pack from GitHub
2. Extract the downloaded zip file and open the .exe
3. A popup notice states that it is part of AnWave and if you would like to visit the site, you can dismiss this by clicking "No", since you just came from there
4. Here you can click on "Install" for the Microsoft Dolby Digital Plus Encoder and Decoder, these are the ones we want.
5. After installing both, restart your device
6. Enjoy AC-3 content working again!

Plex settings

It's important to note that in the case of Plex (and possibly others) the audio settings should also match your speaker setup. If your audio equipment is stereo, like for example, speakers built into your monitor or desktop stereo speakers then you should also make sure Plex knows this, otherwise some content will be quieter because Plex will attempt to direct play all audio channels through your stereo setup, some channels are quieter than others, which results in an overall lower volume in some cases; a more detailed explanation can be viewed here.

• Go to Settings, and in the left panel where you see Plex for Windows, click Player
• Toggle Show Advanced top right of the Player settings page
• In the Audio Device dropdown setting, change this from Auto to your actual Audio Device
• Depending on your audio device you can choose Basic, Optical, or HDMI
• Then set the Audio Channels that match your system.

Now Plex will "intelligently" downmix the audio to the correct format, as outlined in their own documentation, and EAC-3 5.1 content should also be a bit louder on Stereo setups.

Hopefully this helps people that have discovered some of their content no longer has audio, but also why some content is quieter than others. For example, Emby does not appear to have the same issues that Plex has with audio output, content that has no sound in Plex will work in Emby, because Emby includes many codecs native to the Windows app.

Source

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