.wav files: Linear PCM, 8000 Hz, 16-bit, mono
.al files: raw A-Law files, which don’t contain a header
Preferred format is alaw.
Converting the file in Audacity to 16 bit aLaw:
- Open the recording.
- Use the dropdownmenu on the top left of the wave form and select "Split to Mono".
- Now you can delete one of the wave forms, you only need one.
- Use the Drop down menu again and select the "Format" and select "16 bit PCM".
- Click the "Tracks" and select "Resample" and select 8000.
- Set Project Rate (Hz) to 8000
- Now Select File and "Export Audio".
- Select "Other Uncompressed files" as the type.
- Click the "Options..." button and select Header as "RAW (header-less)" and Encoding as "A-Law". Click ok.
- Change the file extension to ".al" and save.
Converting the file to 16 bit mono wave in Audacity:
- Open the recording.
- Use the dropdownmenu on the top left of the wave form and select "Split to Mono".
- Now you can delete one of the wave forms, you only need one.
- Use the Drop down menu again and select the "Set Sample Rate" and select "16 bit PCM".
- Click the "Tracks" and select "Resample" and select 8000.
- Now Select File and "Export Audio".