Patent ID: 7181079
Filing Date: 2007-02-20
Classification: H04N

Abstract:
1. Apparatus for analyzing a spectral representation of an analysis signal comprising audio and/or video data that has been generated by encoding and decoding an original signal according to an encoding algorithm, wherein the encoding algorithm has a quantization step, wherein the quantization step serves to quantize at least part of original spectral coefficients or spectral coefficients derived from the original spectral coefficients of a spectral representation of the original signal by using a quantization step width, wherein the quantization step of the encoding algorithm includes grouping of the original spectral coefficients into scale factor bands, wherein a scale factor is assigned to each scale factor band, and wherein the quantization step further comprises weighting the original spectral coefficients in a scale factor band with an encoding amplification factor, wherein the encoding amplification factor is in a predetermined relation to a scale factor for the scale factor band, comprising: a grouper for grouping analysis spectral coefficients or spectral coefficients derived from the analysis spectral coefficients of the spectral representation of the analysis signal in scale factor bands; a greatest common divisor calculator for at least approximately calculating the greatest common divisor of the grouped analysis spectral coefficients or the spectral coefficients derived from the analysis spectral coefficients in a scale factor band, to obtain the quantization step width used in the quantization step for the analysis spectral coefficients or for the analysis spectral coefficients derived from the analysis spectral coefficients or an integer multiple of it; a scale factor calculator for calculating the scale factor for the scale factor band by evaluating the predetermined relation between the encoding amplification factor and the scale factor, wherein the calculated greatest common divisor is used in the predetermined relation instead of the encoding amplification factor; and a scale factor evaluator for evaluating the calculated scale factors, wherein in the case where all scale factors deviate from an integer raster by a constant amount, a total scaling of the analysis time signal to the original time signal by a factor corresponding to the amount is established.