| 摘要 |
Digitalized encoded audio signals for transmission over disturbed channels are composed of a series of information blocks made of information units containing various types of information, such as control information, scale factor information and information on encoded scanning values derived from partial-band and/or transformation coding at the source. The units of information concerning the encoded scanning values are allocated to a determined spectral structure. Before its transmission or storage, the encoded audio signal is subjected to a channel encoding dependent on the desired error protection. When errors are recognized, they are corrected, and when the errors cannot be corrected, they are concealed. For the channel encoding of the units of information concerning the encoded scanning values, a variable bit error protection is provided depending on the allocation of the individual information unit to a determined spectral structure, i.e., units of information concerning the encoded scanning values of lower frequency audio signal fractions are given a higher bit error protection than units of information concerning the encoded scanning values of higher frequency audio signal fractions. The variable error protection to be selected for the individual information units is further determined depending on the admissible duration and frequency, according to subjective criteria, of the applied error concealment.
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