| 摘要 |
A multi-channel input signal is downmixed to a multi-channel output signal by one of four downmixing routines. The downmixing routines compute the output channels by multiplying each of a number of coefficients by one of the input channels, and then accumulating the resulting products to form the output channels. For efficiency, the four downmixing routines perform various different computations on the input channels using different combinations of coefficients. For a given combination of input and output channels, a downmixing routine is chosen that will perform all of the necessary computations for downmixing the input to the output, while minimizing the number of computations performed with zero-valued coefficients. As a result, computational efficiency is increased by avoiding unnecessary computations, while at the same time, programming effort and program size are maintained at reasonable levels.
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