Low bit rate high-quality MDCT audio coding of the 3GPP EVS standard
Srikanth Nagisetty, Zongxian Liu, Takuya Kawashima, Hiroyuki Ehara, Xuan Zhou, Bin Wang, Zexin Liu, Lei Miao, Jon Gibbs, Lasse Laaksonen, Venkatraman Atti, Vivek G. Rajendran, Venkatesh Krishnan, Hosang Sung, Kihyun Choo · 2015
This paper presents a low bit-rate MDCT coder, which is adopted as a part of the recently standardized codec for Enhanced Voice Services. To maximize codec performance for NB to SWB input signals for low bit-rates (7.2 to 16.4 kbps), new adaptive bit-allocation and spectrum quantization schemes, which emphasize perceptually important spectrum while efficiently coding full spectrum, was introduced into the low bit-rate MDCT coder. Further, small symbol switched Huffman coding is exploited for reducing the bits consumption for quantizing band energies of the spectrum. Finally, the performance of the coder is illustrated with some listening test results.