Apparatus and method for encoding and decoding multichannel signal
Disclosed is an apparatus for encoding and decoding multi-channel signals. The apparatus for encoding the multi-channel signals may shift a phase of the multi-channel signals based on a characteristic of the multi-channel signals. An encoded bitstream with respect to the multi-channel signals may be generated using a downmix signal and a residual signal extracted from the phase-shifted multi-channel signals.
1. An encoding apparatus, comprising:
a parameter extractor to extract, from multi-channel signals, a plurality of parameters indicating a relationship between a plurality of channels constituting the multi-channel signals;
a phase shifter to shift a phase of the multi-channel signals to produce a phase-shifted multi-channel signal using a phase angle that is calculated for each of the plurality of parameters and the plurality of channels;
a signal extractor to extract, from the phase-shifted multi-channel signals and using the plurality of parameters, a downmix signal and a residual signal; and
a bitstream generator to generate a bitstream by encoding the downmix signal, the residual signal, and the plurality of parameters.
2. The encoding apparatus of claim 1 , wherein the phase shifter shifts the phase of the multi-channel signals so that each multi-channel signal has a same phase.
3. The encoding apparatus of claim 1 , wherein the phase shifter shifts the phase of the multi-channel signals by a predetermined amount so that phase difference information between the channels have a value less than or equal to a value of a predetermined angle.
4. The encoding apparatus of claim 1 , wherein the phase shifter shifts the phase of the multi-channel signals so that a change in the phase angle is minimized.
5. The encoding apparatus of claim 1 , wherein the plurality of parameters include at least two of a channel level differences (CLD) between the plurality of channels, an inter-channel phase difference (IPD) between the plurality of channels, and an inter-channel coherence (ICC) between the plurality of channels.
6. A decoding apparatus, comprising:
a decoding unit to restore a downmix signal and a residual signal of multi-channel signals, and a plurality of parameters indicating a relationship between a plurality of channels constituting the multi-channel signals to produce a restored down mix signal, a restored residual signal and restored parameters;
an upmixing unit to upmix the restored downmix signal and the restored residual signal into the multi-channel signals, using the restored parameters; and
a restoring unit to restore at least one of a phase and a magnitude of the multi-channel signals upmixed using the restored parameters.
7. An encoding apparatus, comprising:
a parameter extractor to extract, from multi-channel signals, a plurality of parameters indicating a relationship between a plurality of channels constituting the multi-channel signals;
a signal extractor to shift a phase of the multi-channel signals using a phase angle that is calculated for each of the plurality of parameters and a plurality of channels to produce phase-shifted multi-channel signals, and to extract, from the phase-shifted multi-channel signals, a downmix signal and a residual signal; and
a bitstream generator to generate a bitstream by encoding the downmix signal, the residual signal, and the plurality of parameters.
8. An encoding method for encoding multi-channel signals in an encoding apparatus, the method comprising:
extracting, by a parameter extractor of the encoding apparatus, from multi-channel signals, a plurality of parameters indicating a relationship between a plurality of channels constituting the multi-channel signals;
shifting, by a phase shifter of the encoding apparatus, a phase of the multi-channel signals, using a phase angle that is calculated for each of the plurality of parameters and the plurality of channels to produce phase-shifted multi-channel signals;
extracting, by a signal extractor of the encoding apparatus, from the phase-shifted multi-channel signals and using the plurality of parameters, a downmix signal and a residual signal; and
generating, by a bitstream generator of the encoding apparatus, a bitstream by encoding the downmix signal, the residual signal, and the plurality of parameters.
9. A non-transitory computer-readable medium comprising a program for instructing a computer to perform the method of claim 8 .
10. An encoding method, comprising:
extracting, from multi-channel signals, a plurality of parameters indicating a relationship between a plurality of channels constituting the multi-channel signals;
shifting a phase of the multi-channel signals, using a phase angle that is calculated for each of the plurality of parameters and the plurality of channels to produce phase-shifted multi-channel signals, and extracting, from the phase-shifted multi-channel signals, a downmix signal and a residual signal; and
generating a bitstream by encoding the downmix signal, the residual signal, and the plurality of parameters.
11. A decoding method for decoding multi-channel signals in a decoding apparatus, the method comprising:
restoring, by a decoding unit of the decoding apparatus, a downmix signal and a residual signal of multi-channel signals, and a plurality of parameters indicating a relationship between a plurality of channels constituting the multi-channel signals to produce a restored down mix signal, a restored residual signal and restored parameters;
upmixing, by an upmixing unit of the decoding apparatus, the restored downmix signal and the restored residual signal into the multi-channel signals, using the restored parameters; and
restoring, by a restoring unit of the decoding apparatus, at least one of a phase and a magnitude of the multi-channel signals upmixed using the restored parameters.