| 摘要 |
<p>For audio coding, the MPEG-2 standard provides for a spatial representation by multi-channel reproduction. In order to ensure backwards compatibility with MPEG-1 signals, the signals of the multi-channel sound channels are matrixed. Before being matrixed, the audio signals generally have their levels reduced in order to prevent overdriving. In order to balance again the reduction at the encoder end, an option that is provided in the MPEG-2 standard is for a decoder to raise the output levels again. If, however, a transmission error then occurs in the multi-channel section, the decoder cannot carry out the reverse matrixing. In that case, only the MPEG-1-compatible signal component will be decoded. The auditory impression can therefore be disturbed in various ways during the changeover to MPEG-1 decoding. According to the invention, in the event of errors being detected in the supplementary signals, a portion of the multi-channel audio signals is cross-faded to the MPEG-1-compatible signal components and/or a further portion of the multi-channel audio signals is set to zero, in which case, at the decoder end, level raising of the MPEG-1-compatible signal components can be effected prior to the cross-fading of the multi-channel audio signals. <IMAGE></p> |
