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EVRC and SMV 3GPP2 defined, required in CDMA networks Narrowband codecs (8kHz audio sampling rate) Frame-based with 20 ms frames Encodes at 3 (EVRC) or 4 (SMV) different rates, varying from 8.55 to 0.8 kbps depending on audio input. Thus highly variable packet sizes. The average bit-rate is dependent on codec modes, Each mode selects the used encoding rates differently to provide different average rates. Lacks DTX and needs to transmit all frames. One mode in the payload format requires a single frame per packet. |