Author: Andre Adrian
work: Andre DoT Adrian AT dfs DoT de
home: adrianandre AT compuserve DoT de
This directory is about Acoustic Echo Cancellation for Voice over IP. If you have two-way communication with speakerphone (hands-free telephone) you need Acoustic Echo Cancellation (AEC). The following files explain AEC and can patch the sources of the Kphone GNU/Linux program to a Kphone program with AEC.
Note: The AEC in Kphone and Simph323 are outdated. The latest AEC version is included in intercom. See http://andreadrian.de/intercom/
There is also a Frequently Asked Questions file.
echounterdruck.pdf German article about AEC draft-aec-03.txt Paper that explains AEC (with source-code) kphone_2004-10-11-06-55.tgz Patch Source files for Kphone 4.0.3 (GPL) simph323_aec_1.0.install Simph323 AEC installation simph323_aec_1.0.tgz Patch Source files for Simph323
Install the Source files
First get Kphone 4.0.3 sources from http://www.wirlab.net/kphone/
Put the kphone-4.0.3.tar.gz and kphone_2004-10-11-06-55.tgz in one directory. cd in this directory and
# prepare compile kphone
tar xzf kphone-4.0.3.tar.gz
# load AEC patch
tar xzf kphone_2004-10-11-06-55.tgz
# check stereo mode settings (mic-in or line-in)
# read the file and follow the instructions
# compile kphone AEC version
# Start kphone with
# Kphone Configuration (the IP-addresses are examples - use your own!)
# Menu "Identity..."
# Full Name = Andre s2
# User Part of SIP URL = EDDF_LAP2
# Host Part of SIP URL = 192.168.1.2
# Auto Register = No
# Menu "Audio Preferences..."
# OSS Device Mode = ReadOnly/WriteOnly
# Preferred Codec = iLBC
# Ringing tone (system bell) = Use ringing tone
# Menu "Phone Book"
# Person = Andre s2
# Identity = EDDF_LAP1@192.168.1.1
# Add Identity to Contacts List = Yes
Have fun and don't hesitate to write me an e-mail if you have problems.
Remember, AEC is a real-time algorithm normally run on a DSP. This
is not Visual Basic for Apprentice we are doing here. It is more like
rocket science (okay, it is more like computer science). You mess with
Mrs. Murphy here. Please believe me, this source code is working.
The iLBC Codec is from Global IP Sound, see
Kphone was originally developed by Billy Biggs.
Today it is maintained by Wirlab.
Read the file
http://andreadrian.de/intercom/draft-conference-01.txt for more information about VoIP telephone conference (with C++ source code).