초록 ▼

In the transmission of audio signals, the audio signal is digitally represented by use of quadrature mirror filtering in the form a plurality of spectral sub-band signals. The quantizing of the sample values in the sub-bands, e.g. 24 sub-bands, is controlled to the extent that the quantizing noise l

In the transmission of audio signals, the audio signal is digitally represented by use of quadrature mirror filtering in the form a plurality of spectral sub-band signals. The quantizing of the sample values in the sub-bands, e.g. 24 sub-bands, is controlled to the extent that the quantizing noise levels of the individual sub-band signals are at approximately the same level difference from the masking threshold of the human auditory system resulting from the individual sub-band signals. The differences of the quantizing noise levels of the sub-band signals with respect to the resulting masking threshold are set by the difference between the total information flow required for coding and the total information flow available for coding. The available total information flow is set and may then fluctuate as a function of the signal.

대표청구항 ▼

In a method of transmitting or storing digitalized audio signals having spectral and temporal structure, wherein each audio signal is represented by a plurality of spectral, quantized components, the method comprising the steps of: producing the plurality of spectral, quantized components from the d

In a method of transmitting or storing digitalized audio signals having spectral and temporal structure, wherein each audio signal is represented by a plurality of spectral, quantized components, the method comprising the steps of: producing the plurality of spectral, quantized components from the digitalized audio signal, with each component having respective level values associated with the spectral and temporal structure of the audio signal; obtaining masking thresholds corresponding to the human auditory system for each component; changing the quantizing of the individual components on the basis of the respective masking thresholds of the human auditory system to produce coded components, thereby reducing the magnitude of a total information flow required for the transmission or storage of all coded components which fluctuates in dependence on the spectral and temporal structure of the audio signal; transmitting or storing the coded components; decoding the transmitted or stored coded components; and reconstructing a broadband, digital audio signal from the decoded components; the improvement wherein the step of changing the quantizing of the components is on the basis of the level values of each component so that the quantizing noise levels of the individual components have approximately the same level difference from the respective masking threshold of the individual components, the differences of the quantizing noise levels of the components being set by the difference between the required total information flow and the total information flow available for coding.