Warning: passthru() has been disabled for security reasons in _audioconverter_scheduler_ffmpeg_helper

I am using the audioconverter module with the audiorecorderfield module in Drupal 7 with ffmpeg on my own vps running Aegir and Nginx. The audioconverter module has stopped converting wav files to mp3. Here's the error;

Warning: passthru() has been disabled for security reasons in _audioconverter_scheduler_ffmpeg_helper() (line 358 of /mysite/drupal-7.16/sites/all/modules/audioconverter/audioconverter.module).

And in my logs;

MESSAGE: executing: /usr/bin/ffmpeg -i /mysite/drupal-7.16/sites/default/files/1354856044.wav /mysite/drupal-7.16/sites/default/files/1354856044.wav.mp3

MESSAGE: Audio conversion failed. FFMPEG reported the following output: 

SEVERITY: error

MESSAGE: converted file is an empty file.

I can see the wav file is created by the audiorecorderfield module but the audioconverter module is failing on the conversion.

Here is my ffmpeg info;

ffmpeg version 0.7.13, Copyright (c) 2000-2011 the FFmpeg developers
built on Jun 13 2012 14:01:54 with gcc 4.4.5
configuration: --enable-libdc1394 --prefix=/usr --extra-cflags='-Wall -g ' --cc='ccache cc' --enable-shared --enable-libmp3lame --enable-gpl --enable-libvorbis --enable-pthreads --enable-libfaac --enable-libxvid --enable-postproc --enable-x11grab --enable-libgsm --enable-libtheora --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-libspeex --enable-nonfree --disable-stripping --enable-avfilter --enable-libdirac --disable-decoder=libdirac --enable-libfreetype --enable-libschroedinger --disable-encoder=libschroedinger --enable-version3 --enable-libopenjpeg --enable-libvpx --enable-librtmp --extra-libs=-lgcrypt --disable-altivec --disable-armv5te --disable-armv6 --disable-vis
libavutil    50. 43. 0 / 50. 43. 0
libavcodec   52.123. 0 / 52.123. 0
libavformat  52.111. 0 / 52.111. 0
libavdevice  52.  5. 0 / 52.  5. 0
libavfilter   1. 80. 0 /  1. 80. 0
libswscale    0. 14. 1 /  0. 14. 1
libpostproc  51.  2. 0 / 51.  2. 0
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

Safe mod is OFF in php.ini so I don't know why audioconverter is not working.

Solution

Solved by disabling passthru by removing "passthru" from disable_functions in php.ini

Yay!