Sony AVCHD .MTS AC-3 audio doesn't work on Premiere Pro?

Hi AntDX316,

I hope the suggestions provided by the experts were helpful. You mentioned that the transcoded ProRes 422 or MP4 doesn't work. Could you please let us know the app you used for transcoding?

Thanks,

Sumeet

The issue is not Adobe. It's Windows. You see, Adobe since version 2018 has restricted AC-3 codec support only to native OS support, which meant that Adobe can no longer include an AC-3 decoder or encoder in its video programs. Windows 11 previously supported the AC-3 codec for playbach until that support was removed beginning with the 24H2 feature update (only for clean installations of such newer feature update versions). Thus, if your Windows 11 PC was a fresh installation of 24H2 or 25H2, you get absolutely no AC-3 support at system level. Hence the need for the workaround mentioned above.

And VLC detects the AC-3 audio because it incorporates a "free-to-use" component of the AC-3 decoder, which is then partially reverse-engineered by the ffmpeg people to mimic the behavior of the actual Dolby Digital decoder and then restricted only for use in VLC and cannot be utilized by any other program. (Both Handbrake and Shutter Encoder also do this, as well because they, like VLC, use ffmpeg for both decoding and encoding media.) As a result, VLC (and Handbrake and Shutter Encoder as well) cannot use the trademarked Dolby Digital logo.

Windows 11 doesn't support AC3 audio ... so you have to add the audio codec to your computer, and there are several ways to get a free download. There's also several posts on this forum about getting that installed.

Search for AC3 audio codec ... that will bring up several.

This is listed in one post ...

https://www.free-codecs.com/download/ac3_filter.htm

See here:

https://community.adobe.com/t5/premiere-pro-discussions/premiere-pro-2025-version-25-0-0-doesn-t-accept-mts-files-with-sound/td-p/15016954

and here:

https://www.majorgeeks.com/files/details/dolby_ac_3ac_4_installer.html