The Enhanced Voice Services (EVS) coder consists of a multi-rate (5.9 to 128 kbps) audio coder optimized for operation with voice and music/mixed content signals, a source controlled rate scheme including a voice/sound activity detector and a comfort noise generation system, and an error concealment mechanism to combat the effects of transmission errors and lost packets. Jitter buffer management is also provided with EVS. The EVS coder also provides enhanced interoperation with AMR-WB over all nine source bitrates from 6.6 to 23.85 kbps. The EVS speech coder is capable of switching its bitrate every speech frame upon command.

EVS Codec Overview

The memory and CPU details are generic Standard specifications.

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EVS Codec Technical Specifications

  • Bandwidth: 50 – 24000 Hz
  • Standardized: 3GPP 2014
  • Technology: ACELP & Transform Coding
  • Bit rate: 5.9 to 128 kbps and interoperable with AMR-WB (6.6 to 23.85 kbps)
  • Delay (msec): 25 - 32
  • Frame size (msec): 20
  • Lookahead (msec): 5 - 12
  • Quality: Narrowband, Wideband, SuperWideband and Fullband
  • Complexity (MIPS): 86
  • ROM (bytes): 285K
  • RAM (bytes): 175K