Staple Design – Gwilym GJ …think, design, build, enjoy, think, evolve…..

Trixbox, FreePBX and System Recordings using Audacity

I am building an Asterisk box for Wastebusters using the excellent Trixbox CE mixup of Asterisk, FreePBX and LAMP. It is on a Toshiba laptop andas of yesterday I had everything working well except uploading system recordings and the outgoing SMTP for voice mail.

This morning I managed to solve the System Recording using a free opensource audio recorder toolbox Audacity. The steps to record a message for an IVR are below.

1. Get the latest version of Audacity, I think it needs to be later than 1.3 (currently in Beta).
2. First set the “Project Rate (hz)” at the bottom on the screen to 8000hz.
3. Record a message (standard Audacity help files cover this including editing/clipping the message) you should have something like the below. Note at this point it is in Stereo and the wrong bit rate and sample format to use in Asterisk.
4. First change the track to mono. Click on the “Audio Track” menu just to the left of the blue waveform and and go down to “Split Stereo to Mono”, this should create two tracks. You can delete one of them.
5. Clicking on the “Audio Track” menu again scroll down to “Set Sample Format” and change it to “16-bit PCM”.
6. Go to the main “File” menu in the top of the window and pull down to “Export”. Where it says “Save as Type” select “Wav (Microsoft)” it should say “signed 16 bit – PCM” after “Microsoft”. Click “Save”.
7. An “Edit Meta Data” box should come up. Just click OK.
8. A box called “Advanced Mixing Options” will come up and there should be one “Output Channel” if so click ok.
9. Upload to Asterisk using “System Recordings” or directly and test.

I tried all the Wav compressions available in Audacity GSM, Ulaw and Alaw but none of them worked in Asterisk. Strange.

Updated: 16th June 2010 – new bitrate setting.