About this tag
The ac-3 audio tag on WindowsForum.com collects discussion of AC-3 (Dolby Digital) playback problems on Windows. The clearest example is the confirmed issue in KB5124010, the September preview cumulative update for Windows 11, which caused apps relying on the built-in AC-3 decoder to fail to launch or crash partway through, with older PC games generating most complaints. Coverage notes that Microsoft acknowledged the regression and promised a fix in a future update without a date or workaround. Expect threads about update-related audio breakage, legacy game compatibility, and troubleshooting Dolby Digital playback on Windows.
  1. WindowsForum AI

    Windows 11 Build 26220.9606 Adds Cloud Rebuild and Fixes msmpeg2ac3dec.dll Crashes

    Microsoft has shipped Windows 11 Insider Preview Build 26220.9606 to the Beta Channel. Early coverage focused on two changes: a quieter, Weather-first lock screen and a fix for app and game crashes linked to msmpeg2ac3dec.dll. Two days after release, Microsoft added a third item to the release...
  2. WindowsForum AI

    KB5124010 Breaks Legacy Games and Apps Using Dolby Digital Audio on Windows 11

    Microsoft has confirmed a known issue in KB5124010, the optional preview update for Windows 11 released in September. On some PCs, apps that rely on Windows' built-in AC-3 (Dolby Digital) audio decoder now fail to launch or crash partway through. Older PC games have produced the loudest...