Jari Mäkinen

AMR-WB+: a new audio coding standard for 3rd generation mobile audio services

Highly efficient low-rate audio coding methods are required for new compelling and commercially interesting applications of streaming, messaging and broadcasting services using audio media in 3rd generation mobile communication systems. After an audio codec selection phase, 3GPP has standardized the extended AMR-WB (AMR-WB+) codec that provides a unique performance at very low bit rates from below 10 kbps up to 24 kbps. This paper discusses the requirements imposed by mobile audio services and gives a technology overview of AMR-WB+ as a codec matching these requirements while providing outstanding audio quality.

The effect of source based rate adaptation extension in AMR-WB speech codec

This paper presents a source based rate adaptation concept for AMR wideband speech codec. The source based rate adaptation algorithm selects the multi rate codec mode based on the input speech characteristics and coding parameters to minimise the average bit rate. The presented concept introduces up to 50% reduction in average bit rate without any degradation in speech quality. The benefit of source based adaptation is in increasing the system capacity in conversational services as well as storage size in messaging type of applications.

Low Complex Audio Encoding for Mobile, Multimedia

Computational resources in a mobile terminal and in wireless transmission channels set strict requirements for audio coding in mobile multimedia applications. This paper introduces, a low complex audio encoding method enabling high-quality audio for mobile multimedia. The presented method is the low complexity version of the extended AMR-WB audio encoder in the 3GPP standards. The encoder was designed based on requirements of the 3GPP multimedia messaging service (MMS)