As a simple and easy-to-use mp4 file format muxer for Mac, Lion, and Mountain Lion 10.8, ,Subler quickly remuxes mkv or mov files to mp4 or add new subtitles tracks to your mp4 file. The common use for Mac OS X users with Subler is to remux MKV or MOV file to MP4 with AC3 passthrough. Thanks to Subler, it saves tons of time and there is no more headach for video files conversion.
However, with the realease of Mountain Lion, many Mountain Lion users just find that Subler no longer work on Mountain Lion. Some users may find it even won’t start on Mountain Lion. Some users get “Audio Converter Error – The Audio Converter can not be initialized” when trying to convert the MKV file to MP4 with setting the Action “AC-3 to AAC”.
The issue is related to a52codec, the ac3 core audio component that is bundled with perian.
How to Fix
By doing some tricks, the Perian can still play AC3 audio codec on Mac Mountain Lion. But only in multi-channel (stereo), no 5.1 surround sound (6 channels) can be supported right now.
Step 1: Donwnload the a52codec.component
Step 2: Unzip A52Codec
Unzip it. It should replace the one in /Library/Audio/Plug-Ins/Components or ~/Library/Audio/Plug-Ins/Components (the Library folder in your Home folder).
Step 3: Select “multi-channel output” in perian preferences.
Then every thing will work fine. Perian can now play MKV AC3, AVI AC3, MP4 AC3 on Mountain Lion, but remember the audio is only in stereo.
If you wish play MKV AC3 in 5.1 surround sound on Mountain Lion, you will need to convert MKV to MP4 AC3 5.1 or MP4 AAC 5.1 by some professional tool.