Making stereo out of a single recorded channel

One problem we have run into is recording a single left or right audio channel into the

Single channel of audio needing to be both channels
Single channel of audio needing to be both channels

Zoom H4n recorder using a single microphone.  This is how to convert stereo audio recordings (in this case the Zoom H4n, Zoom 1, Zoom 2) to single mono sounds that play through both speakers / headphones / audio channels.

When we get back to the edit bay with Final Cut Pro X (FCPX), we only have a single side working.  We really want to fill that null, blank or empty audio channel with something.  Usually an exact duplicate of the channel with some useful audio.

More than once, we have run into this problem.  But it’s infrequent except when the camera or recording device does not do channel redirecting like the Sony PD-150.  That ability was very handy and saved time in editing.

To make this audio file into a stereo selection, bring up the inspector window (Command-4) and select Audio.

With your audio clip to be modified selected, find the area with the Channel Configuration.

Click Dual Mono.

Doing this will spread the single audio track across both left and right channels.  Since

Dual Mono from single channel stereo FCPX
Dual Mono from single channel stereo FCPX

one of the channels is empty anyway, just deselect that channel.

Now the clip will play in both the left and right channels.

There are other methods, like making a copy of the audio track and then creating a compound file.  However, this adds additional complexity to the project and it only takes a one frame error to create all sorts of problems with the audio.  Although we used to do the multiple clip technique in Final Cut Pro 6 (and 7), this method is far more effective and less error prone.  Really, there is not too much to go wrong with this approach.