3 files changed, 59 insertions, 1 deletions
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 70bcc3e..dfb40b3 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -1 +1,2 @@
-EXTRA_DIST = README-pcm-oss README-jack README-polyp
+EXTRA_DIST = README-pcm-oss README-jack README-polyp \
+	upmix.txt vdownmix.txt
diff --git a/doc/upmix.txt b/doc/upmix.txt
new file mode 100644
index 0000000..b8a6da4
--- /dev/null
+++ b/doc/upmix.txt
@@ -0,0 +1,34 @@
+UPMIX PLUGIN
+============
+
+The upmix plugin is an easy-to-use plugin for upmixing from 1 or 2
+channel stream to 4 or 6-channel stream.  The number of channels to be
+expanded is determined by the slave PCM.  For example, the following
+PCM defines upmixing to 5.1 from 2-6 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"
+		channels 6
+		delay 10
+	}
+
+As default, 15ms delay is used.
+
+The center and LFE channels are the average of sum of left and right
+signals.
+
+The accepted format is currently only S16.
diff --git a/doc/vdownmix.txt b/doc/vdownmix.txt
new file mode 100644
index 0000000..0e1403f
--- /dev/null
+++ b/doc/vdownmix.txt
@@ -0,0 +1,23 @@
+VDOWNMIX PLUGIN
+===============
+
+The vdownmix plugin is a downmixer from 4-6 channels to 2-channel
+stereo headphone output.  This plugin processes the input signals with
+a simple spacialization, so the output sounds like a kind of "virtual
+surround".
+
+For example, define the below:
+
+	pcm.!surround51 {
+		type vdownmix
+		slave.pcm "default"
+	}
+	pcm.!surround40 {
+		type vdownmix
+		slave.pcm "default"
+	}
+
+and the outputs from video player to these PCMs are converted to the
+default 2.0 output with a proper downmix.
+
+The accepted format is currently only S16.