ADAPTIVE RESIDUAL AUDIO CODING

AN AUDIO SIGNAL HAVING AT LEAST TWO CHANNELS CAN BE EFFICIENTLY DOWN-MIXED INTO A DOWNMIX SIGNAL AND A RESIDUAL SIGNAL, WHEN THE DOWN-MIXING RULE USED DEPENDS ON A SPATIAL PARAMETER THAT IS DERIVED FROM THE AUDIO SIGNAL AND THAT IS POST-PROCESSED BY A LIMITER TO APPLY A CERTAIN LIMIT TO THE DERIVED SPATIAL PARAMETER WITH THE AIM OF AVOIDING INSTABILITIES DURING THE UP-MIXING OR DOWN-MIXING PROCESS. BY HAVING A DOWN-MIXING RULE THAT DYNAMICALLY DEPENDS ON PARAMETERS DESCRIBING AN INTERRELATION BETWEEN THE AUDIO CHANNELS, ONE CAN ASSURE THAT THE ENERGY WITHIN THE DOWN- MIXED RESIDUAL SIGNAL IS AS MINIMAL AS POSSIBLE, WHICH IS ADVANTAGEOUS IN THE VIEW OF CODING EFFICIENCY. BY POST PROCESSING THE SPATIAL PARAMETER WITH A LIMITER PRIOR TO USING IT IN THE D0WN-MIXING, ONE CAN AVOID INSTABILITIES IN THE DOWN- OR UP- MIXING, WHICH OTHERWISE COULD RESULT IN A DISTURBANCE OF THE SPATIAL PERCEPTION OF THE ENCODED OR DECODED AUDIO SIGNAL.