Using audacity

index page

This is one of a series of pages detailing attempts to play Ambisonic sound on cheap everyday equipment. This is not the ideal way to do it, but it does allow for experimentation. The faltering steps reported here are offered as one person's experience not as suggestions of how anything should be done!!

1. Making Audacity multichannel

  1. Goto Edit then Preferences (or Control-P). This can be slow to come up …
  2. Goto File Formats
  3. Goto the third 'paragraph' entitled When exporting tracks
  4. click on Use Advanced Mixing Options
  5. Then OK

Currently there seems no way to make Audacity recognise channels as grouped (except for stereo!).

2. Converting WXY to WXYZ

Pantophonic recordings (a full 360 degree horizontal soundstage) may be recorded with or without a 'height track' (Z).

Periphonic recordings (fully 3-dimensional) have (at least four tracks: WXYZ).

Both to discover what you have and to convert WXY to WXYZ you can open them in Audacity.

  1. Open the file (File and Open).
  2. Then File, Export As … WAV.
  3. Choose 4 channels, and an extra blank track is added
  4. The new file may not have the official/standard ambisonic headers. There are utilities to fix this, but as the created 4-track plays fine on mplayer and thus far I have not published any files, I am happy -for the moment- with a possibly non-compliant file. But see next section.

(There is now a Ambman utility ambman --wxy2amb that will do this conversion without a need to open the file.)

3. Saving as Wave Format Extensible

You can save your files as Wave Format Extensible (which is almost a .amb file) by doing the following:

  1. Goto Edit then Preferences (or Control-P). This can be slow to come up …
  2. Goto File Formats
  3. Goto the fourth 'paragraph' entitled Uncompressed Export Format
  4. choose Other, a further dialogue box will appear
  5. choose WAVEX
  6. choose whatever you want, probably 24 bit PCM, or 32 bit float?
  7. Then OK to close the small dialogue box
  8. Then OK to close the preferences box/window

Some horrible presumptions will be recorded in the file header (e.g. if it is a first order file, it will map the tracks to 'quadrophonic' speaker positions … !!). Such metadata does not affect how you use the file, it is though rather anti-social for file-exchange and archiving. I have written a utility (wav2amb) which corrects the headers as well as one ambinfo) that displays them.

September 2007 (last updated October 2007).

Copyright © 2007 Michael Chapman.