The KSAC3_DOWNMIX structure specifies whether the program channels in an AC-3-encoded stream need to be downmixed to accommodate the speaker configuration.
Specifies whether to downmix. If TRUE, downmixing to fewer channels is enabled. The number of output channels depends on the number of speakers present (as specified by the KSPROPERTY_AUDIO_CHANNEL_CONFIG property). If FALSE, input and output channels are mapped to speakers on a one-to-one basis. In other words, input channel 0 is mapped to output channel 0, input channel 1 is mapped to output channel 1, and so on, up to the number of encoded channels or speakers, whichever is smaller.
Specifies how the output channels are encoded. If TRUE, the output channels are first encoded as two Dolby Surround Pro Logic channels, Lt and Rt. If FALSE, the output channels do not use Dolby Surround Pro Logic encoding.
This structure is used by the KSPROPERTY_AC3_DOWNMIX property.
For information about the mapping of output channels to speakers, see KSPROPERTY_AUDIO_CHANNEL_CONFIG.