Add Speex pre-processing plugin

Added Speex pre-processing filter plugin for denoise, AGC, etc.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 56 insertions, 1 deletions

diff --git a/doc/Makefile.am b/doc/Makefile.am
index 41a7ebe..3e89be8 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -1,3 +1,4 @@
 EXTRA_DIST = README-pcm-oss README-jack README-pulse README-maemo \
 	upmix.txt vdownmix.txt samplerate.txt a52.txt lavcrate.txt \
-	speexrate.txt
+	speexrate.txt speexdsp.txt
+
diff --git a/doc/speexdsp.txt b/doc/speexdsp.txt
new file mode 100644
index 0000000..875fc19
--- /dev/null
+++ b/doc/speexdsp.txt
@@ -0,0 +1,54 @@
+Speex Preprocessing Plugin
+==========================
+
+This plugin provides a pre-processing of a mono stream like denoise
+using libspeex DSP API.  You can use the plugin with the plugin type
+"speex" like below:
+
+	pcm.my_pcm {
+		type speex
+		slave.pcm "default"
+	}
+
+Then record like
+
+	% arecord -fdat -c1 -Dplug:speex foo.wav
+
+so that you'll get 48kHz mono stream with the denoising effect.
+
+Right now, the plugin supports only a mono stream.
+The accepted format is only S16.
+
+The following parameters can be set optionally:
+
+* frames
+
+  This controls the frames of the intermediate buffer.  This
+  corresponds to the latency of the filter.  As default it's 64.
+
+* denoise
+
+  A boolean value to enable/disable the denoise function.  Default is
+  yes.
+
+* agc
+   
+  A boolean value to enable/disable the auto-gain control function.
+  Default is no.
+
+* agc_level
+
+  A float value for the automatic gain-control level.  Default is 8000.
+
+* dereverb
+
+  A boolean value to enable/disable dereverb function.  Default is no.
+
+For example, you can enable agc like
+
+	pcm.my_pcm {
+		type speex
+		slave.pcm "default"
+		agc 1
+		agc_level 8000
+	}