Asterisk app_amd for FreeSWITCH

This is an implementation of Asterisk's answering machine detection (voice
activity detection) for FreeSWITCH.

Currently, in limited testing, we are able to get satisfactory results in
determining what is a human and what is a machine, but there is much more to
do:

• Emit events when a decision is made (Not sure, Machine, or Human).
• Make sure that we are unlocking and cleaning up where necessary.

Building

To build this module, all you need to do is type make, but because it relies
on pkg-config and FreeSWITCH, you need to point pkg-config to where
FreeSWITCH is installed before building:

host$ export PKG_CONFIG_PATH=/usr/local/freeswitch/lib/pkgconfig/
host$ make

Sample Configuration

Just put a file like this in your freeswitch installation, in conf/autoload_configs/amd.conf.xml

<configuration name="amd.conf" description="mod_amd Configuration">
  <settings>
    <param name="silence_threshold" value="256"/>
    <param name="maximum_word_length" value="5000"/>
    <param name="maximum_number_of_words" value="3"/>
    <param name="between_words_silence" value="50"/>
    <param name="min_word_length" value="100"/>
    <param name="total_analysis_time" value="5000"/>
    <param name="after_greeting_silence" value="800"/>
    <param name="greeting" value="1500"/>
    <param name="initial_silence" value="2500"/>
  </settings>
</configuration>