Convert a Surround sample down to Stereo

I have a collection of sound effects (folley, ambience, explosions, etc) that are in 5.1 surround. I’d like to convert them down to stereo files so I can use them in Ableton Live. For most i’m fine with taking all the channels and converting them to stereo, so batch processing would be nice. I tried using a chain with the Export WAV option, but it only outputs the file to mono, not stereo, and i can’t find an option for changing that. Any ideas, or am i overlooking something? I’m on OSX Lion using the Audacity beta version.

Some of the tools “stick” in the last mode you used. Try exporting a plain stereo show and then go back and try Chains again.


nope, didn’t work. as you say, using ExportWAV on a stereo sample works…it does export as another stereo. but then following it up with trying to export a surround sample gives me only a mono track.

if i use Export from the File menu, then exporting as an .aiff or .wav always gives a stereo file from the original surround file. but using the chain ExportWAV gives a mono. i don’t understand that…

i have hundreds to do so i’m obviously looking for a batch process.

I don’t think you can do that as a batch process in Audacity because when you import a multi-channel sound file it will create multiple mono tracks, so until you manually set each track to where you want it in the stereo field (for example with the track Pan sliders) you have a multi-track mono show.
I don’t use Macs so I don’t know what alternative applications you can try.

yeah, it definitely is working that way. but it doesn’t make sense to me…

i thought the batch chain commands use the functions found within Audacity that are used during non-batch processing (the function found with the File, Edit, etc menus).

so why does Export from the file menu nicely give a stereo file, yet ExportWAV in the chains gives a mono? Aren’t they both using the Export function?

unfortunately the ExportWAV doesn’t have any parameter adjustments, so i can’t just choose “stereo”. who creates these chain scripts? can they adjust the ExportWAV one, or is there scripting option i can use to export my files as stereo?


The commands that are available in Chains are hard coded into Audacity. The “scripts” that string together a number of commands are user editable (see )

Importing a single multi-channel file and then exporting it, I was surprised that you were getting a stereo file, but I’ve just checked with a 4 channel AIFF file and found that the first two channels are set as left and right, so this will export as a stereo track.

I don’t know why you are not getting a stereo file when you use a Chain. I suspect that it may be a bug. I’ll see what I can find out and get back to you (may be a couple of days).

Thanks. Yeah, hopefully it is a bug.

I went to that link you gave and at the bottom of the screen read this: Parameters for export formats cannot be set in "Edit Chains: To configure export parameters for the chain, click File > Export… to access the File Export Dialog, click “Options” to set and save the parameters, then cancel the export.

So i tried it. When using Wav or Aiff as the export format there are no options. So i chose the WAV(Microsoft) option under “Other Uncompressed Files”. It’s Options are only for 16-bit, 24-bit, etc. Nothing about stereo or mono. I still tried several choices (which all gave stereo files when used directly), but when i then tried the ExportWav chain it still only gave a mono file. I even tried deleting and recreating a chain with the ExportWav, but still mono. I definitely think it’s a bug at this point. Makes no sense.

Hopefully this can be fixed. I love Audacity and the ability to set up chains is nice. I just need stereo tracks in the end.

Seems to me that Chains does not see the first two “left” and “right” tracks as left and right, but just as mono. Chains would export the multichannel file as stereo giving you the same result as manual export, if there was a way after import to make the first two tracks into a stereo pair. You would do this manually by clicking in the Name of the first track, then “Make Stereo Track”, or you could use the keyboard sequence SHIFT +M, M, M, M, ENTER.

Unfortunately, “Use Custom Mix” in the Import / Export preferences which allows channel allocation when exporting manually doesn’t work with Chains.

I can’t think of any any workaround to this, unless Steve can come up with a Nyquist plug-in to run in the chain (before the Export command) that mixes the first two tracks. If so you would then have to use an experimental version of Audacity that supports Nyquist plug-ins in Chains rather than only the built-in effects.

Incidentally, multi-channel OGG, AC3 and WMA files import entirely as mono tracks, so will export as mono unless panned. I presume only libsndfile (the importer for uncompressed PCM) does left/right allocation on the first two tracks.


the surround files i’m bringing in do have the first two tracks labeled “left” and “right” and are recognized as “left channel” and “right channel” in the track name drop-down menu. all the rest are listed as mono.

if the chain function uses or basically points to the same Export command that is found in the File menu, then there’s definitely a bug in the chain command. otherwise it would function the same as the Export command under File. so it must be different and not function the same…which is unfortunate for me.

if there’s a way to directly use the Export function from within the chains then i’m set.

i’ve been trying some other apps out there and so far no luck. is this really such an uncommon task?? I still feel that it’s possible in Audacity…if one of the coders has the time to look into why the chain export functions differently…and perhaps “fixing” it.

Unfortunately, it would be hard to recommend fixing this right now. We are only doing fixes for data loss and instability issues at the moment so we can get a new 2.0 “stable” release out. Fixing the issue you’ve identified where Chains doesn’t understand left and right tracks could be quite disruptive and time consuming, because some of the “Chains” code is built on top of code from another open source program called CleanSpeech .

As far as I can see, the export code in Chains uses an MP3 export routine and then renames the file to its correct extension when passed to another exporter. I’m pretty sure this is the reason for the problem.

How about iTunes - does that downmix to stereo if you convert a file to WAV?

1 iTunes > Preferences
2 Click on the leftmost “General” tab
3 Click the Import Settings button half way down on the right
4 In the “Import Using” dropdown, choose “WAV Encoder”
5 Click OK and OK
6 Select the files to be converted, then right-click or control-click over them and choose “Create WAV version”