Digital audio limiter

DETAILED DESCRIPTION We claim: 1.
A signal processing system comprising a perceptual encoder responsive to an input audio signal limited to a first peak amplitude, a perceptual decoder responsive to said perceptual encoder, wherein the output of said decoder is a processed audio signal not limited to said first peak amplitude, estimating means for generating an estimated peak amplitude of said processed audio signal, and limiting means responsive to said processed audio signal for generating an output audio signal limited to a second peak amplitude by applying a gain factor to a portion of the total bandwidth of said processed audio signal, said gain factor established in response to said estimated peak amplitude.
2.
A signal processing system comprising processing means for generating a processed audio signal in response to an input audio signal having an apparent loudness and being limited to a first peak amplitude, wherein said processed audio signal has an apparent loudness substantially the same as said apparent loudness of said input audio signal but is not limited to said first peak amplitude, wherein said processing means for generating said processed audio signal comprises a perceptual-coding system, estimating means for generating an estimated peak amplitude of said processed audio signal, and limiting means responsive to said processed audio signal for generating an output audio signal limited to a second peak amplitude by applying a gain factor to a portion of the total bandwidth of said processed audio signal, said gain factor established in response to said estimated peak amplitude.
3.
A signal processing system according to claim 1 or 2 wherein said processed audio signal comprises signal samples and wherein said estimating means comprises means for upsampling said signal samples.
4.
A signal processing system according to claim 1 or 2 wherein said estimating means generates said estimated peak amplitude in response to the full bandwidth of said processed audio signal.
5.
A signal processing system according to claim 1 or 2 wherein said estimating means comprises means for generating said estimated peak amplitude in response to a first peak amplitude estimate of a first sub-signal representing said processed audio signal within a first frequency subband and in response to a second peak amplitude estimate of a second sub-signal representing said processed audio signal within a second frequency subband