ADVANCES IN SOURCE-CONTROLLED VARIABLE BIT RATE WIDEBAND SPEECH CODING (original) (raw)

On the architecture of the cdma2000® variable-rate multimode wideband (VMR-WB) speech coding standard

International Conference on Acoustics, Speech, and Signal Processing, 2004

Description and design of the source-controlled variable-rate multimode wideband (VMR-WB) codec recently selected by the 3 rd Generation Partnership Project 2 (3GPP2) for the cdma2000® system in Rate-Set II are presented. This paper gives an overview of the codec and the methodologies that enabled high quality wideband coding at average data rates ranging from TIA/EIA/IS-733 ADR to that of TIA/EIA/IS-127. The codec has three modes of operation at different average data rates and a fourth mode that is interoperable with 3GPP/AMR-WB (ITU-T/G.722.2). Despite the interoperability constraint, the codec was capable of meeting the aggressive performance requirements through the use of novel techniques such as noise suppression, efficient signal classification, new coding types optimized for stable voiced and unvoiced frames, novel post-processing technique for periodicity enhancement in the lower frequency band, and improved frame erasure concealment mechanisms.

On the architecture of the cdma2000/spl reg/ variable-rate multimode wideband (VMR-WB) speech coding standard

2004 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2004

Description and design of the source-controlled variable-rate multimode wideband (VMR-WB) codec recently selected by the 3 rd Generation Partnership Project 2 (3GPP2) for the cdma2000® system in Rate-Set II are presented. This paper gives an overview of the codec and the methodologies that enabled high quality wideband coding at average data rates ranging from TIA/EIA/IS-733 ADR to that of TIA/EIA/IS-127. The codec has three modes of operation at different average data rates and a fourth mode that is interoperable with 3GPP/AMR-WB (ITU-T/G.722.2). Despite the interoperability constraint, the codec was capable of meeting the aggressive performance requirements through the use of novel techniques such as noise suppression, efficient signal classification, new coding types optimized for stable voiced and unvoiced frames, novel post-processing technique for periodicity enhancement in the lower frequency band, and improved frame erasure concealment mechanisms.

On the architecture, operation, and applications of VMR-WB: the new cdma2000 wideband speech coding standard

IEEE Communications Magazine, 2006

This article is an overview of the architecture and operation of the VMR-WB5 a source- and network-controlled variable-rate multimode codec designed for robust processing of wideband speech. To enable a smooth transition from legacy narrowband voice services, VMR-WB is also capable of processing conventional telephone-bandwidth speech. The VMR-WB codec is interoperable with AMR-WB at certain bit rates, thus eliminating quality degradation and additional delay due to transcoding

The adaptive multirate wideband speech codec (AMR-WB

IEEE Transactions on Speech and Audio Processing, 2002

This paper describes the Adaptive Multirate Wideband (AMR-WB) speech codec recently selected by the Third Generation Partnership Project (3GPP) for GSM and the third generation mobile communication WCDMA system for providing wideband speech services. The AMR-WB speech codec algorithm was selected in December 2000 and the corresponding specifications were approved in March 2001. The AMR-WB codec was also selected by the International Telecommunication Union-Telecommunication Sector (ITU-T) in July 2001 in the standardization activity for wideband speech coding around 16 kb/s and was approved in January 2002 as Recommendation G.722.2

A candidate proposal for a 3GPP adaptive multi-rate wideband speech codec

2001 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.01CH37221), 2001

This paper describes an adaptive multi-rate wideband (AMR-WB) speech codcc proposcd for the GSM system and also for the evolving Third Generation (3G) mobile speech services. The speech codec is based on SB-CELP (Splitband-Code-Excited Linear Prediction) with five modes operating bit rates from 24kbit/s down to S.lkbit/s. The respective channel coding schemes are based on RSC (Recursive Systematic Code) and UEP (Unequal Error Protection). Both, source and channel codec are designed as homogenous as possible to guarantee robust transmission on current and future mobile radio channels.

An embedded adaptive multi-rate wideband speech coder

2001

This paper presents a multi-rate wideband speech coder with bit rates from 8 to 32 kb/s. The coder uses a splitband approach, where the input signal, sampled at 16 kHz, is split into two equal frequency bands from 0-4 kHz and 4-8 kHz, each of which is decimated to an 8 kHz sampling rate. The lower band is coded using the adaptive multi-rate (AMR) family of high-quality narrowband speech coders, while the higher band is represented by a simple but effective parametric model. A complete solution including this wideband speech coder, channel coding for various GSM channels, and dynamic rate adaptation, easily passed all Selection Rules and ranked second overall in the 3GPP AMR Wideband Selection Testing. Besides the high performance, additional advantages of the embedded split-band approach include ease of implementation, reduced complexity, and simplified interoperation with narrowband speech coders

Noise Reduction Method for Wideband Speech Coding

We present a new low complexity noise reduction (NR) method based on spectral subtraction and overlap-add analysis/synthesis. A voicing dependent cut-off frequency is introduced, dividing the speech spectrum into two parts. In lower end, the NR gain function varies with frequency bins to minimize distortion at pitch harmonic frequencies while maximizing the suppression between them. In higher end, the gain function is estimated per critical band reducing energy variations. The gain function is further smoothed over time with a smoothing factor adaptive with the actual NR gain to pre- vent distortion on voiced speech onsets. The NR is as a part of VMR-WB speech codec recently selected as a new 3GPP2 stan- dard for wideband speech applications in cdma2000 3G wireless system.

Efficient methods for high quality low bit rate wideband speech coding

2002

This paper describes efficient encoding and decoding methods for achieving high quality wideband speech at low rates. CELPbased technologies have been successful in achieving high quality speech at low hit rates, however, new efficient techniques are needed to maintain high speech quality when the model is applied to wideband signals. This article discusses some techniques that improve the performance of the CELP model including efficient perceptual weighting and pitch codebook, and decoding techniques such as gain smoothing, periodicity enhancement, and high frequency generation. These techniques have been incorporated in the AMR-WB (adaptive multi-rate widehand) codec selected by 3GPP and ITU-T, where high quality widehand speech can he maintained at hit rates around 13 kbitis.

The adaptive multi-rate wideband codec: history and performance

2002

This paper gives the history and performance of the Adaptive Multi-Rate Wideband (AMR-WB) speech codec recently selected by the Third Generation Partnership Project (3GPP) for GSM and the third generation mobile communication WCDMA system for providing wideband speech services. The AMR-WB speech codec algorithm was selected in December 2000, and the corresponding specifications were approved in March 2001. In July 2001, the AMR-WB codec was also selected by ITU-T in .the standardization activity for wideband speech coding around 16 khids. The adoption of AMR-WB by ITU-T is of significant importance since for the first time the same codec is adopted for wireless as well as wireline services. AMR-WB uses an extended audio bandwidth from 3.4 kHz to 7 kHz and gives superior speech quality and voice naturalness compared to 1 and 3d generation mobile communication systems.