RTP Payload for Comfort Noise Robert Zopf Lucent Technologies

Speech Communication System with DTX

Voice Activity Detector (VAD) - classify speech frame as active or inactive Discontinuous Transmission (DTX) - update rate of background noise parameters Comfort Noise Generation (CNG) - analysis of background noise parameters (encoder) and synthesis of comfort noise (decoder)

ITU-T G.711 Appendix II Comfort noise payload definition approved at ITU-T February 2000 SG16 tested (MOS) using G.729B VAD/DTX and example algorithm (described in Appendix) using 10th order spectral model equivalent to G.711 without comfort noise flexible for use with any codec guidelines for use in Appendix

CN Payload Format Energy Level equivalent to previous drafts. Spectral Content - Reflection Coeffs (quantized indices Ni) Level is mandatory, spectrum optional 0th order model reduces to previous def.

Open Issues compatibility with existing Level Only implementations 1 CN frame per RTP packet (to determine model order) multiple channels must use the same model order