Apparatus and method for constructing a multi-channel output signal or for generating a downmix signal

Method of constructing a multi-channel output signal using an input signal and parametric side information, the input signal including a first input channel and a second input channel derived from an original multi-channel signal, the original multi-channel signal having a plurality of channels, the plurality of channels including at least two original channels, which are defined as being located at one side of an assumed listener position, wherein a first original channel is a first one of the at least two original channels, and wherein a second original channel is a second one of the at least two original channels, and the parametric side information describing interrelations betweens original channels of the multi-channel original signal, comprising:

• determining a first base channel by selecting one of the first and the second input channels or a combination of the first and the second input channels, and determining a second base channel by selecting the other of the first and the second input channels or a different combination of the first and the second input channels, such that the second base channel is different from the first base channel;
• and synthesizing a first output channel using the parametric side information and the first base channel to obtain a first synthesized output channel which is a reproduced version of the first original channel which is located at the one side of the assumed listener position, and synthesizing a second output channel using the parametric side information and the second base channel, the second output channel being a reproduced version of the second original channel which is located at the same side of the assumed listener position.

Apparatus for generating a downmix signal from a multi-channel original signal, the downmix signal having a number of channels being smaller than a number of original channels, comprising:

• means for calculating a first downmix channel and a second downmix channel using a downmix rule;
• means for calculating parametric level information representing an energy distribution among the channels in the multi-channel original signal;
• means for determining a coherence measure between two original channels, the two original channels being located at one side of an assumed listener position;
• and
• means for forming an output signal using the first and the second downmix channels, the parametric level information and only at least one coherence measure between two original channels located at the one side or a value derived from the at least one coherence measure, but not using any coherence measure between channels located at different sides of the assumed listener position.

Method of generating a downmix signal from a multi-channel original signal, the downmix signal having a number of channels being smaller than a number of original channels, comprising:

• calculating a first downmix channel and a second downmix channel using a downmix rule;
• calculating parametric level information representing an energy distribution among the channels in the multi-channel original signal;
• determining a coherence measure between two original channels, the two original channels being located at one side of an assumed listener position;
• and forming an output signal using the first and the second downmix channels, the parametric level information and only at least one coherence measure between two original channels located at the one side or a value derived from the at least one coherence measure, but not using any coherence measure between channels located at different sides of the assumed listener position.

A computer-readable medium having a computer-executable instruction for performing a method of constructing a multi-channel output signal using an input signal and parametric side information, the input signal including a first input channel and a second input channel derived from an original multi-channel signal, the original multi-channel signal having a plurality of channels, the plurality of channels including at least two original channels, which are defined as being located at one side of an assumed listener position, wherein a first original channel is a first one of the at least two original channels, and wherein a second original channel is a second one of the at least two original channels, and the parametric side information describing interrelations betweens original channels of the multi-channel original signal, comprising:

• determining a first base channel by selecting one of the first and the second input channels or a combination of the first and the second input channels, and determining a second base channel by selecting the other of the first and the second input channels or a different combination of the first and the second input channels, such that the second base channel is different from the first base channel;
• and synthesizing a first output channel using the parametric side information and the first base channel to obtain a first synthesized output channel which is a reproduced version of the first original channel which is located at the one side of the assumed listener position, and synthesizing a second output channel using the parametric side information and the second base channel, the second output channel being a reproduced version of the second original channel which is located at the same side of the assumed listener position.

A computer-readable medium having a computer-executable instruction for performing a method of generating a downmix signal from a multi-channel original signal, the downmix signal having a number of channels being smaller than a number of original channels, comprising:

• calculating a first downmix channel and a second downmix channel using a downmix rule;
• calculating parametric level information representing an energy distribution among the channels in the multi-channel original signal;
• determining a coherence measure between two original channels, the two original channels being located at one side of an assumed listener position;
• and forming an output signal using the first and the second downmix channels, the parametric level information and only at least one coherence measure between two original channels located at the one side or a value derived from the at least one coherence measure, but not using any coherence measure between channels located at different sides of the assumed listener position.