UPMIX PLUGIN

============

The upmix plugin is an easy-to-use plugin for upmixing to 4 or

6-channel stream.  The number of channels to be expanded is determined

by the slave PCM or explicitly via channel option.  For example, the

following PCM defines upmixing to 5.1 from 1-6 channels input:

	pcm.upmix51 {

		type upmix

		slave.pcm "surround51"

	}

You can use this PCM as a default one by defining below:

	pcm.!default "plug:upmix51"

The upmix plugin copies left and right channels to rear left and right

with a certain delay.  The delay size can be specified by "delay" PCM

option in msec.  For example, to set 10ms delay in the above case:

	pcm.upmix51 {

		type upmix

		slave.pcm "surround51"

		delay 10

	}

As default, 15ms delay is used.

The channel option specifies the number of channels of output.  Either

4 or 6 channels are supported.  When 0 is passed, the plugin tries 4

or 6 channels appropriately suitable for the slave pcm.  The channel

option is useful if the slave PCM has no strict input condition (like

plug or route plugin).

	pcm.myupmix {

		type upmix

		slave.pcm "something"

		channels 6

	}

The center and LFE channels are the average of sum of left and right

signals.

The accepted format is currently only S16.