Enhanced Voice Services
|Type of format||Audio|
|Standard||3GPP TS 26.441|
Enhanced Voice Services (EVS) is a superwideband speech audio coding standard. It offers up to 20 kHz audio bandwidth and has high robustness to delay jitter and packet losses due to its channel aware coding and improved packet loss concealment. It has been developed in 3GPP and is described in 3GPP TS 26.441. The application areas of EVS consist of improved telephony and teleconferencing, audiovisual conferencing services, and streaming audio.
Work on EVS was started in 2007. The standardization process lasted from 2010 to 2014, being completed in December 2014 with 3GPP Release 12. The codec was developed collaboratively among chipset, handset and infrastructure manufacturers as well as operators and technology providers. These included Ericsson, Fraunhofer IIS, Huawei, Nokia, NTT, NTT DOCOMO, Orange, Panasonic, Qualcomm, Samsung, VoiceAge, and the ZTE Corporation.
EVS employs similar concepts to its predecessors, such as AMR-WB, to which it retains backward-compatibility. It switches between speech and audio compression modes depending on the content, using ACELP and MDCT.
The following features are present in EVS:
- source-controlled variable bit-rate (SC-VBR)
- voice/sound activity detector (VAD)
- comfort noise generation (CNG)
- error concealment (EC) for packet loss in networks
- channel-aware mode to improve frame/packet error resilience
- jitter buffer management (JBM)
Input sampling rates for EVS can be 8, 16, 32, and 48 kHz. It supports the following bitrates (in kbps) for different bandwidths:
- Narrowband (NB): 5.9, 7.2, 8, 9.6, 13.2, 16.4, 24.4
- Wideband (WB): 5.9, 7.2, 8, 9.6, 13.2, 13.2 channel-aware, 16.4, 24.4, 32, 48, 64, 96, 128 (6.6 ~ 23.85 for AMR-WB IO)
- Super-wideband (SWB): 9.6, 13.2, 13.2 channel-aware, 16.4, 24.4, 32, 48, 64, 96, 128
- Fullband (FB): 16.4, 24.4, 32, 48, 64, 96, 128
Bitrates can be switched every 20 ms.
- Atti, V.; Sinder, D. J.; Subasingha, S.; Rajendran, V.; Dewasurendra, D.; Chebiyyam, V.; Varga, I.; Krishnan, V.; Schubert, B. (2015-04-01). "Improved error resilience for volte and VoIP with 3GPP EVS channel aware coding". 2015 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP): 5713–5717. doi:10.1109/ICASSP.2015.7179066.
- Lecomte, J.; Vaillancourt, T.; Bruhn, S.; Sung, H.; Peng, K.; Kikuiri, K.; Wang, B.; Subasingha, S.; Faure, J. (2015-04-01). "Packet-loss concealment technology advances in EVS". 2015 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP): 5708–5712. doi:10.1109/ICASSP.2015.7179065.
- The 3GPP Enhanced Voice Services (EVS) codec. Nokia white paper.
- Enhanced Voice Services (EVS) Codec. Fraunhofer Technical Paper, 2015
- MPEG LA Facilitating Development of Enhanced Voice Services Patent Pool License. MPEG LA News Release, 20.01.2016.
- Järvinen, Kari. "Enhanced Voice Services Codec for LTE". 3GPP.