The recently standardized 3GPP codec for Enhanced Voice Services (EVS) offers new features and improvements for low-delay real-time communication systems. Based on a novel, switched low-delay speech/audio codec, the EVS codec contains various tools for better compression efficiency and higher quality for clean/noisy speech, mixed content and music, including support for wideband, super-wideband and full-band content. The EVS codec operates in a broad range of bitrates, is highly robust against packet loss and provides an AMR-WB interoperable mode for compatibility with existing systems. This paper gives an overview of the underlying architecture as well as the novel technologies in the EVS codec and presents listening test results showing the performance of the new codec in terms of compression and speech/audio quality
EVS, the newly standardized 3GPP Codec for Enhanced Voice Services (EVS) was developed for mobile services such as VoLTE, where error resilience is highly essential. The presented paper outlines all aspects of the advances brought during the EVS development on packet loss concealment, by presenting a high level description of all technical features present in the final standardized codec. Coupled with jitter buffer management, the EVS codec provides robustness against late or lost packets. The advantages of the new EVS codec over reference codecs are further discussed based on listening test results
The current paper is concerned with an effective method to quantize a spectrum envelope of a speech signal without having an inter-frame prediction. In this paper, we proposed a method referred to as dynamic bit allocation-split vector quantization (DBA-SVQ). The main feature of this structure is that it makes use of the ordering property of line spectral frequencies (LSF) and exploits multiple codebooks, normalization and the DBA technique. As a result, we can limit the dynamic range of LSF sub-vectors and allocate different numbers of bits in accordance with the range sizes to maximize the overall efficiency of quantization. The performance is compared with delta line spectral pairs (LSP) VQ, which is used in EVRC-B, demonstrating reduction in spectral distortion (SD).
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