EVRC Speech Codec B


EVRC ADAPTIVE DIGITAL'S ENHANCED VARIABLE RATE CODEC B

EVRC - B  SPEECH CODER    C64x

DESCRIPTION

Enhanced Variable Rate Codec B (EVRC-B) is a speech codec used by CDMA (Code Division Multiple Access) networks. EVRC-B is an extension to EVRC and compresses each 20 millisecond FRAMES of 8000 Hz, 16-bit sampled speech input into output frames of one of the four different sizes: Rate 1 - 171 bits/frame, Rate 1/2 - 80 bits/frame, Rate 1/4 - 40 bits/frame, Rate 1/8 - 16 bits/frame.

One significant enhancement in EVRC-B is the use of 1/4-rate frames that were not used in EVRC. The EVRC-B makes use of the intermediate coding rates through increased awareness of the nature of the individual speech samples. This provides lower average data rates compared to EVRC, for a given voice quality.

Data sheet: .pdf

Coding Rate:8.5, 4.0, 2.0, and 0.8 kbps

Sampling Rate: 8 kHz

Delay: 20 milliseconds

EVRC FEATURES

  1. Functions are C-callable.

  2. Multi–Channel capable.

  3. Can be integrated with echo cancellers, and tone detection/regeneration.

AVAILABILITY

ADT EVRC is available on the TMS320C6000™ DSP Family

C64x™DSP Generations


SPECIFICATIONS

EVRC- B C64xx

All memory requirements are in units of byte.

Software MIPS Program Memory Data Memory Scratch Per-Channel Data Memory
Average Max
Encode 50.2 83.5 263.5k 0.7k 3008 7240
Decode 11.1 27.1 2176
LAST UPDATE: 04/02/2010

FUNCTIONS


APPLICATIONS

Wireless/Mobile/Personal Communications (base-stations and handset)

 

 

 

 

PRODUCTS