| 摘要 |
An audio encoder, which is capable of encoding multiple-channel signals so that only a downmixed signal is decoded and of further generating specific auxiliary information necessary for dividing the downmixed signal, is provided. An audio encoder ( 10 ), which compresses and encodes audio signals of N-channels (N>1), includes a downmixed signal encoding unit ( 11 ) which encodes the downmixed signal obtained by downmixing the audio signals, and an auxiliary information generation unit ( 12 a) which generates auxiliary information necessary for decoding the downmixed signal encoded by the downmixed signal encoding unit ( 11 ) into N-channel audio signals. The auxiliary information generation unit ( 12 a) includes transformation units ( 121 ) and ( 122 ) which transform audio signals respectively into frequency domain signals, a detection unit ( 123 ) which detects phase difference information and gain ratio information each indicates a degree of difference between frequency domain signals, and a quantization unit ( 125 ) which quantizes, for each frequency band, the phase difference information and gain ratio information detected by the detection unit ( 123 ) using the quantization precision setting table ( 124 ). The quantization precision setting table ( 124 ) functions as a division unit which divides a frequency band of a frequency domain signal into plural sub-bands.
|
