Combined audio coding minimizing perceptual distortion

Abstract

An audio encoder in which two or more preferably different encoders cooperate to generate a joint encoded audio signal. Encoding parameters of the two or more encoders are optimized in response to a measure of distortion of the joint encoded audio signal in accordance with a predetermined criterion. The distortion. measure is preferably a perceptual distortion measure. In one encoder embodiment comprising a sinusoidal and a waveform encoder, a constant total bit rate for each audio frame is distributed between the two encoders so as to minimize perceptual distortion for both the first and the second encoder. Other embodiments consider a set of encoding parameters that is larger than only those that minimize the perceptual distortion of the first encoder. In some embodiments, perceptual distortion may be minimized by optimizing encoding via optimizing entire encoding templates, i.e. a complex set of encoding parameters, for the separate encoders. The separate encoders may either be cascaded or operate in parallel, or in a combination of these. Two or more audio segments are preferably taken into account in the optimizing procedure. A corresponding audio decoder comprises separate decoders corresponding to the separate encoders of the audio encoder that encoded the audio signal. Decoded signal parts from these decoders are then added to produce the final audio signal. The presented audio encoding is efficient and provides a high sound quality because the encoding scheme is flexible and adapts to specific demands for each audio excerpt.