Apparatus and method for selecting one of a first encoding algorithm and a second encoding algorithm using harmonics reduction

Apparatus for selecting one of a first encoding algorithm comprising a first characteristic and a second encoding algorithm comprising a second characteristic for encoding a portion of an audio signal to acquire an encoded version of the portion of the audio signal, comprising:

• a long-term prediction filter configured to receive the audio signal, to reduce the amplitude of harmonics in the audio signal and to output a filtered version of the audio signal;
• a first estimator for using the filtered version of the audio signal in estimating a SNR (signal to noise ratio) or a segmental SNR of the portion of the audio signal as a first quality measure for the portion of the audio signal, the first quality measure being associated with the first encoding algorithm, wherein estimating said first quality measure comprises performing an approximation of the first encoding algorithm to acquire a distortion estimate of the first encoding algorithm and to estimate the first quality measure based on the portion of the audio signal and the distortion estimate of the first encoding algorithm without actually encoding and decoding the portion of the audio signal using the first encoding algorithm;
• a second estimator for estimating a SNR or a segmental SNR as a second quality measure for the portion of the audio signal, the second quality measure being associated with the second encoding algorithm, wherein estimating said second quality measure comprises performing an approximation of the second encoding algorithm to acquire a distortion estimate of the second encoding algorithm and to estimate the second quality measure using the portion of the audio signal and the distortion estimate of the second encoding algorithm without actually encoding and decoding the portion of the audio signal using the second encoding algorithm;
• and
• a controller for selecting the first encoding algorithm or the second encoding algorithm based on a comparison between the first quality measure and the second quality measure,
• wherein the first encoding algorithm is a transform coding algorithm, a MDCT (modified discrete cosine transform) based coding algorithm or a TCX (transform coding excitation) coding algorithm and wherein the second encoding algorithm is a CELP (code excited linear prediction) coding algorithm or an ACELP (algebraic code excited linear prediction) coding algorithm.