INTERNATIONAL ORGANISATION FOR STANDARDISATION
ORGANISATION INTERNATIONALE DE NORMALISATION
ISO/IEC JTC 1/SC 29/WG 11
CODING OF MOVING PICTURES AND AUDIO

ISO/IEC JTC 1/SC 29/WG 11 N7468
Poznań, PL – July 2005

1         Introduction

SSC is a generic audio coder employing a universal coding concept based on the most recent psycho-acoustic knowledge. The bit rate reduction techniques that are applied in this universal concept are suitable for coding both audio and speech at a competitive low bit rate. In the SSC coder four objects can be discerned. The first three constitute a monaural representation of the audio signal: Tonal, Noise and transient components. A fourth object is able to capture the stereo image.

2         Motivation

A parametric representation of an audio or speech signal inherently provides for high quality tempo and pitch scaling in the decoder for no additional cost. The parametric stereo module is coder agnostic. A powerful combination is that with HE-AAC, also standardized as the HE-AAC v2 profile.

3         Overview of technology

Until now, all high quality low bit rate audio coders are basically perceptual waveform coders, meaning that the coder attempts to reconstruct the input waveform at the decoder output as faithfully as possible, employing a perceptual quality criterion. Pure waveform coding seems to have reached the ceiling of its performance. Recent developments in high quality audio coding are the application of parametric coding techniques. A successful example is the Spectral Band Replication technology that can be combined with waveform coding. In fully parametric-based coding it is assumed that the input signal can be described as a sum of three signal components: a transient signal, a ‘deterministic’ signal and a noise-like signal. The transient signal is a sum of certain well-defined events; one might consider it a codebook of parameterised short-lasting signals. The ‘deterministic’ signal can be described as a sum of sinusoidal components.

[1]        E.G.P. Schuijers, A.W.J. Oomen, A.C. den Brinker and D.J. Breebaart, `Progress on parametric coding for high quality audio.' DAGA, Aachen, 18-20 March 2003. Pp. 860-861.

[2]        A.C. den Brinker, A.J. Gerrits and R.J. Sluijter, `Phase transmission in sinusoidal audio and speech coding.' 115th AES Convention, New York, 10-13 October 2003. Convention Paper 5983.

[3]        'Listening test report on MPEG-4 High Efficiency AAC v2', ISO/IEC JTC 1/SC 29/WG 11/N7137.April 2005, Busan, Korea (Public document)

4         Target applications

Language learning, games (pure parametric) and Mobile telephony, Music download (HE-AAC v2).