New Feature Request - Export of 36 Channel File

Audacity 3 Help Forum
1

[Updated with corrections]

I have a 36-channel w64 file created with another DAW program.

If I read the 36-channel file into Audacity and select a portion of it (for example the first 8 seconds), I can’t export more than 32 channels.

Here’s what I’m doing after I read in the 32-channel file:

I select the region I want on all 36 channels.

I do File → Export Audio → Export to computer → Custom Mapping with Current Selection

(It’s a 96000 Hz Sample Rate / Signed 24-bit PCM Encoding file.)

When I do “Configure” for the Custom Mapping, it only shows 32 output channels. I can’t get 36.

Can anyone advise, please? Or would the development team please consider expanding the Export Audio to more than 32 channels?

Len M.

2

What is a “w64”-file?

3

We’re recording audio that uses much larger files than WAV can handle in a single file.

A WAV file is limited in size to 4 GB.

W64 allows much, much larger file sizes. Most DAWs (including Audacity) support it.

4

From the manual:

When you click on the Configure button in the Export Audio dialog, this dialog appears which presents you with the number of tracks you have in your project and allows you to map these as desired to each of up to

5

Steve wrote: …

-–

I was mistaken: Export Audio only allows us to export to a 32-channel .w64 file under all conditions.

Perhaps Export Audio’s number of channels could be expanded to at least 36 channels for all situations?

6

I think w64 format can support an arbitrary number of channels, so why not 37 channels, or 45, or 128, or 30000000?

7

Indeed.

We have an application that needs 36. But Audacity currently limits it to 32.

8

I’d suggest you use your “other DAW program” instead of Audacity.

36 channel 96000 / 24-bit sounds rather specialist. What’s it for?

1 Like
9

It’s for an Ortho-bilateral ambisonic microphone array. It records for headtracked 360-degree binaural playback with personal HRTF.

https://u.pcloud.link/publink/show?code=XZD6eJJZAmNodmVnXnkN5vXaPuB49bB3nr67

The raw A-format recording has 32 channels. Once it’s encoded into standard second-order B-format it has 36 channels.

10

Ooh that’s interesting.

One possible workaround is to export from Audacity 2 x 18 channel files, then use FFmpeg from the command line to join them into a 36 channel file. I don’t know the exact command off the top of my head, but it’ll be something like:

ffmpeg -i "file_01.w64" -i "file_02.w64" -filter_complex "[0:a][1:a]join=inputs=2:channel_layout=0x0[a]" -map "[a]" -c:a pcm_s24le -ar 96000 "output_36ch.w64"
11

Thanks for the idea.

We’re able to handle 36 channel audio files for simple operations in Plogue Bidule.

Bidule is a simple blocks and wires app intended for MIDI performance, but it works great for ambisonic plugin operations. 32 and 36 channels is no problem for the A- to B-format encoding process, and decoding for the Ortho-bilateral array recordings.

Still, it would be nice to be able to do it all in Audacity.