Enhanced Variable Rate CODEC (EVRC) is a

speech codec Speech coding is an application of data compression of digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic d ...

used in

CDMA Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication ...

networks. It was developed in 1995 to replace the

QCELP Qualcomm code-excited linear prediction (QCELP), also known as Qualcomm PureVoice, is a speech codec developed in 1994 by Qualcomm to increase the speech quality of the IS-96A codec earlier used in CDMA networks. It was later replaced with EVRC s ...

vocoder which used more bandwidth on the carrier's network, thus EVRC's primary goal was to offer the mobile carriers more capacity on their networks while not increasing the amount of bandwidth or wireless spectrum needed.EVRC: Best of Both Worlds
/ref> EVRC uses RCELP technology. EVRC compresses each 20 milliseconds of 8000 Hz, 16-bit sampled speech input into output frames of one of three different sizes: full rate – 171 bits (8.55 kbit/s), half rate – 80 bits (4.0 kbit/s), eighth rate – 16 bits (0.8 kbit/s). A quarter rate was not included in the original EVRC specification and eventually became part of EVRC-B. EVRC was replaced by SMV. Recently, however, SMV itself has been replaced by the new

CDMA2000 CDMA2000 (also known as C2K or IMT Multi‑Carrier (IMT‑MC)) is a family of 3G mobile technology standards for sending voice, data, and signaling data between mobile phones and cell sites. It is developed by 3GPP2 as a backwards-compatible ...

4GV codecs.

4GV Qualcomm's (4G) is a suite of voice speech codecs used by CDMA Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitte ...

is the next generation

3GPP2 The 3rd Generation Partnership Project 2 (3GPP2) is a collaboration between telecommunications associations to make a globally applicable third generation ( 3G) mobile phone system specification within the scope of the ITU's IMT-2000 project. In ...

standards-based EVRC-B codec. 4GV is designed to allow service providers to dynamically prioritize voice capacity on their network as required. EVRC can be also used in 3GPP2 container file format - 3G2.

External links

3GPP2 specification

* - Enhancements to RTP Payload Formats for EVRC Family Codecs

References

Speech codecs 3rd Generation Partnership Project 2 standards {{compu-stub