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Convert all your Asterisk .wav recordings to .mp3

Posted: October 24th, 2008 | Author: | Filed under: Asterisk VoIP, Linux, Tech | Tags: , , , , , , , , , , , , , | 28 Comments »

Update 20100222:
From a helpful contributor. Since the encoding has changed and I haven’t had to do file conversion in years and years.
Check out Ernesto’s script here.

I have had many jobs (consulting and Salary) that have involved using Asterisk in a “Call-Center” environment. Whenever an agent would make a sale, the call would need to be recorded for verification purposes.  Now I could talk about Asterisk and call-recording for pages upon pages, but I will be focusing on large .wav to .mp3 conversion jobs on the Linux/Asterisk server itself.  First off, Asterisk can record calls using several different methods.  The first method being that you setup a feature called Automon in /etc/asterisk/features.conf and use *1 (or whatever you specify) to record a call in progress.  The second method is recording every call that comes in through a specific DID or enters a specific queue.  Another method is to setup a ‘call genie’ that you conference your phone to and it records the entire call-bridge.  There are pros and cons to every type of recording method and format.  You can use GSM, wav, g729, etc. to record calls.  Not matter what method you use, the simple script I wrote will convert your .wav files to .mp3 and also retain the timestamp of when the file was initially created (recorded). The options I use for mlame are what makes this script retain its awesome-ness over time.  The options allow the final-result mp3 to be compressed and compatable with Asterisk.  This means that you can playback your .mp3 files that you converted over Asterisk if you are using a ‘call-genie’ setup. I have also written scripts to convert your .g729/.gsm/etc => .mp3 so if you need one of those scripts leave a comment and I will email it to you (20090908 UPDATE: Check end of post for .g729 to MP3 file conversion script)

Installation Instructions:
1. Download the script to your server.   wget  or download it here.

2. Put the script anywhere you wish, I tend to leave it in my home directory

3. chmod +x

4. You need to install lame.  Get the file from the lame site.

5. Extract the tarball.  For Example…    tar -zxvf lame-398-2.tar.gz

6. cd lame-398-2

7.   ./configure

8. make

9. make install

10. Now copy the mlame file from lame-398-2/misc/mlame to your .wav directory /var/spool/asterisk/monitor (or wherever your .wavs are)

11. chmod +x mlame

12. Edit the  recorddir variable to match your .wav directory path (no trailing ‘/’). The default directory is set to /var/spool/asterisk/monitor

13. Run the script by navigating to the directory and   ./

You should see it take a few seconds for each file and go on.  I usually test it out by letting it convert a few files then Cntrl + C and ls -l the directory to check the filesizes and timestamps.  There is a commented out section at the bottom of that moves the .wav files to a separate directory (easier to check if it worked) and in my case, I keep the old files for a month or so for job security reasons.  If you lose a bunch of verification recordings, you are going to have major problems.

Cron it, at it, and happy converting.


Code for .g729 to MP3 script.  Very dirty, but works, please test on a small group of test files first.
Leave a comment if you need further assistance.

#Author: Gregg Hansen  20080414
#Used to convert from .g729 -in and -out files to .mp3
#Run on Recordings server

for i in `ls /ramdiskunload/*.g729`;
#convert all .g729 to wav first, then soxmix
DST=`echo $i | sed 's/.g729/.wav/g'`
asterisk -rx "file convert $i $DST"
rm -f $i
mv $DST /recordings

#all files should now be in the /recordings directory
#use soxmix and mlame to convert them to one file => mp3

for j in `ls /recordings/*-in.wav`;
INFILE=`echo $j | sed 's/-in/-out/g'`
MIXED=`echo $j | sed 's/-in//g'`
soxmix $j $INFILE $MIXED
rm -f $j
rm -f $INFILE
/root/test/mlame -f -o "-b 16 -m m -q 9 --resample 8" $MIXED

As always, leave a comment if you need help or clarification.