[OSX 10.9.2]

My Mac doesn't think Audacity can open mp4 files, so when I want to do so using "Open with", I have to switch from "Recommended Applications" to "All Applications" so as to select Audacity.

This is only for when I want to extract the audio; I do not want to make Audacity the default app. I am fine with Quicktime being the default.

The question is, can I identify Audacity as being capable of opening an mp4 so I don't always have to switch to "All applications"?

1 Answer 1


You need to edit Audacity's Info.plist file and add mp4 to the list of files it handles.

Using a text editor, open /Applications/Audacity.app/Contents/Info.plist (this is assuming Audacity is installed as Audacity.app, it might be slightly different).

Then, find the section for CFBundleDocumentTypes which should list the supported types like:

<key>CFBundleTypeExtensions</key> <array> <string>...</string> <string>...</string> <string>...</string> </array>

Then just add a new line for mp4: <string>mp4</string> and save the file.

To get the LaunchService to pick up your change, you have to run (in Terminal):

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user

After that, Audacity should show as a Recommended Application for mp4 files.

  • I don't know about Audacity, but for some apps, using this method will have to be redone at every app update because the update is likely to install a new Info.plist file.
    – August
    Dec 15, 2023 at 23:06
  • If the application is "signed" — most are, these days — you will not be able to run them after modifying Contents/Info.plist. The best approach, shown in answers to similar questions on this site, is to use Automator to create a Quick Action to run Audacity from the Finder's contextual menu. Jan 1 at 3:24

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