CHANGES version 25sep2005

version 0.4.1:
  fixed aec_test.cpp
  Tuning of parameter Thold and xfast threshold (from -55dB to -70dB)
  Speaker output only right Line-out channel

version 0.4:
  new Soft decision Adrian DTD
  speex_bits_write() gives different return value with Speex 1.0 and
  Speex 1.1 lib. Emit error message "Update Speex lib to 1.1"
  mix 2040Hz for VHF transmitter activation (not Intercom relevant)
  Common Answer button
  Diversion button
  visualize w vector (TCP connection intercomd to wdisplay.tcl)
  Leaky NLMS algorithm


version 0.3.6:
  Soft decision Adrian DTD instead of Geigel DTD
  Soft decision Acoustic Echo Suppression
  program option -b for no Acoustic Echo Suppression
  Wideband Speex now 27.8kBit/s net (was 20.6kBit/s)


version 0.3.5:
  Reduce number of compile warnings (change signed to unsigned, ...).
  Disable capture switch does no longer freeze intercomd.
  add Wideband Speex Codec (20.6kBit/s)
  option -k works in wideband mode.
  create 2 binaries for narrowband, wideband operation
  

version 0.3.4:
  H-infinity LMS-pw instead of NLMS-pw algorithm. 
  See Haykin, Adaptive Filter Theory, 4. Edition, Chap. 5.10.
  Cutoff Frequency now 2kHz for pre-whitening filters.
  Correct FIR and IIR highpass filters for narrowband/wideband.
  NoiseFloor is now -55dB for all codecs.
  In wideband mode, option -k is broken. Compressing codecs work
  bad in wideband mode. See file Makefile for wideband enabling.
  Work in progress MMX and SSE implementation of dot product dotp().


version 0.3.3:
  experimental Wide Band support. 
  Open PCM out changed back to 0.3.1 behaviour. 


version 0.3.2:
  experimental Wide Band support. All codecs use 16kHz sample rate,
  options -f and -k are broken. Payload types are wrong.
  Open PCM out only on demand fixed in audio_write().


version 0.3.1:
  open UDP ports at program start in intercom.tcl (slow CPUs bug fix)


version 0.3:
  Packet Loss Concealment for G.729, GSM-EFR
  Packet Loss default behaviour is silence, optional PLC
  check receive RTP packets payload type
  SSRC does no longer change for the station (unique identifier)
  fill RTP CSRC field at telephone conference
  Avoid audio loops (multiple UDP RTP connections) by checking CSRC
  Up/Down counter for active station notification in HMI
  alternative fixed point acoustic echo cancellation - see aecfix.cpp
  application ping from intercom.tcl to intercomd via TCP connection


version 0.2.2:
  Codec specific ambient noise default because of AEC divergence
  Allow change of stability parameter delta for NLMS-pw any time
  Kill intercomd at intercom destroy (Close Button)
  Better handling of Operation System jitter
  Packet Loss Concealment for iLBC


version 0.2.1:
  create 2 binaries with GSM-EFR and G.729 because of name conflicts
  add G.726 32kbps codec (ITU-T G.191)


version 0.2:
  use Tcl/Tk tcludp lib for active station and failed station signalling
  use UDP port 5004 for RTP, UDP port 55004 for signalling
  add G.711 A-law, G.711 u-law, GSM codec (ITU-T G.191)
  add G.729 (ITU-T G.729), GSM-EFR (3GPP 46.053) codec
  write-only and read-only audio fd. Open PCM out only on demand


version 0.1:
  first release. Features:
  iLBC codec (RFC3951, RFC3952)
  subset of RTP stack (RFC3550, RFC3551)
  Acoustic echo cancellation
  telephone conference
  intercom.tcl to intercomd process communication via TCP connection