Adaptive Multi-Rate Wideband - AMR Modes

AMR Modes

AMR-WB operates, like AMR, with nine different bit rates. The lowest bit rate providing excellent speech quality in a clean environment is 12.65 kbit/s. Higher bit rates are useful in background noise conditions and for music. Also lower bit rates of 6.60 and 8.85 kbit/s provide reasonable quality especially if compared to narrow band codecs.

All modes are sampled at 16 kHz (using 14-bit resolution) and processed at 12.8 kHz.

The bit rates are the following:

• Mandatory multi-rate configuration
  • 6.60 kbit/s (used for circuit switched GSM and UMTS connections; should only be used temporarily during bad radio connections and is not considered wideband speech)
  • 8.85 kbit/s (used for circuit switched GSM and UMTS connections; should only be used temporarily during bad radio connections and is not considered wideband speech; provides quality equal to G.722 at 48 kbit/s for clean speech)
  • 12.65 kbit/s (main anchor bitrate; used for circuit switched GSM and UMTS connections; offers superior audio quality to AMR at and above this bit rate; provides quality equal to or better than G722 at 56 kbit/s for clean speech)
• Higher bitrates for speech in adverse background noise environments, combined speech and music, and multi-party conferencing.
  • 14.25 kbit/s
  • 15.85 kbit/s
  • 18.25 kbit/s
  • 19.85 kbit/s
  • 23.05 kbit/s (not targeted for full-rate GSM channels)
  • 23.85 kbit/s (provides quality equal to G.722 at 64 kbit/s for clean speech; not targeted for full-rate GSM channels)