Reverse Stereo Left/Right Channels with AC3Filter
I had a unique situation with my headphones a couple of days ago. I needed the left and right channels to be reversed for playing music because the cables weren't long enough to turn them around. Anyway, I searched Google for quite some time but couldn't find anything useful. It's practically impossible to reverse your left and right stereo audio channels on Windows unless your audio drivers have the functionality to do so. For me, I run Realtek HD Audio drivers with my onboard sound, so that was pretty much out of the question. Multiple suggestions linked to 'switching the speaker positions around' (it's quite obvious that would be the first option you would try if the cables were long enough...), and other than those suggestions you simply just couldn't install some piece of software to reverse these channels! I mean, some games, applications, or audio managers have a built-in functionality that enables swapping the stereo channels (such as foobar2000, VLC Media Player, etc.), but for general audio playback this couldn't be accomplished.
It was pretty frustrating.
And then I found a freeware open-sourced program called AC3Filter.
It's branch-off is the MatrixMixer (or Matrix Mixer), but that thing's from 2003 and heavily outdated. So use this.
You'll want to download and install this freeware, open-source audio decoder originally designed to handle AC3/DTS audio playback. But for our purposes we'll only use the mixer included in the bundle.
Somehow and after the installation, open the configuration window and get to the Mixer tab.
At the bottom left there should be a dropdown list under the Matrix preset. Use the "Swap left and right channels" preset and you should be good to go!
AC3Filter supports the latest versions of Window Media Player (Tested with WMP11 on Windows XP Professional SP3) and also others.
I'm not sure if you can get this working with all the audio that comes out of your PC, but using this filter on MPEG (mp3) audio or PCM/SPDIF (whatever the heck these mean) should work.