ALSA LADSPA Plugin Chain For FM Transmission - Revision history

Dlk at 19:12, 24 February 2020

2020-02-24T19:12:27Z

Dlk at 17:20, 19 February 2020

2020-02-19T17:20:34Z

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Dlk at 14:11, 31 December 2019

2019-12-31T14:11:54Z

Dlk at 18:32, 5 April 2014

2014-04-05T18:32:18Z

Dlk: Dlk moved page ALSA LADSPA Plugin Chain F for FM transmission to ALSA LADSPA Plugin Chain For FM Transmission without leaving a redirect

2014-04-05T18:29:32Z

Dlk moved page ALSA LADSPA Plugin Chain F for FM transmission to ALSA LADSPA Plugin Chain For FM Transmission without leaving a redirect

Dlk: Dlk moved page ALSA LADSPA filter chain for FM transmission to ALSA LADSPA Plugin Chain F for FM transmission

2014-04-05T18:29:02Z

Dlk moved page ALSA LADSPA filter chain for FM transmission to ALSA LADSPA Plugin Chain F for FM transmission

Dlk at 18:28, 5 April 2014

2014-04-05T18:28:36Z

Dlk at 18:25, 5 April 2014

2014-04-05T18:25:22Z

Dlk at 18:24, 5 April 2014

2014-04-05T18:24:08Z

Dlk: Created page with "I found a great tool for enhancing audio for FM transmission and adding RDS text to the signal, [http://www.stereotool.com/ Stereo Tool]. It's free to use the basic features ..."

2014-04-05T18:22:53Z

Created page with "I found a great tool for enhancing audio for FM transmission and adding RDS text to the signal, [http://www.stereotool.com/ Stereo Tool]. It's free to use the basic features ..."

New page

I found a great tool for enhancing audio for FM transmission and adding RDS text to the signal, [http://www.stereotool.com/ Stereo Tool]. It's free to use the basic features but it costs $600+ to unlock all of the FM-related features if you want to use them. In the free version they have a beep tone that goes off every few seconds when you are using unlicensed features.

Turns out that it is possible to do similar enhancements using the LADSPA plugins in ALSA. As an example, here's the /etc/asound.conf that I use with my radio station Linux server, a Raspberry Pi using a cheap Behringer U-Control UCA 202 digital/analog converter. (Note the use of the hw:1,0 device for output, which corresponds to the USB DAC device.):

<pre>
# Make USB DAC the default device
pcm.!default {
type hw
card 1
}
ctl.!default {
type hw
card 1
}

# LADSPA plugin chain for radio station processing
pcm.radio {
type plug
slave.pcm "ladspa"
hint {
show on
description "in -> equal -> declip -> compressor -> limiter -> dmix -> out"
}
}

# LADSPA plugins:
# "listplugins" to see the list of installed plugins
# "analyseplugin <filename>" to see plugin controls
# Use "ardour2" to test plugin settings
pcm.ladspa {
type ladspa
slave.pcm dmixplug
path "/usr/lib/ladspa"
plugins {
0 {
# Equalizer - FM curve (approx, should cut at 19kHz, not 16)
label Eq
input {
# 31 Hz, -48 to 24, default -30
# 63 Hz, -48 to 24, default 0
# 125 Hz, -48 to 24, default 0
# 250 Hz, -48 to 24, default 0
# 500 Hz, -48 to 24, default 0
# 1 kHz, -48 to 24, default 0
# 2 kHz, -48 to 24, default 0
# 4 kHz, -48 to 24, default 0
# 8 kHz, -48 to 24, default 0
# 16 kHz, -48 to 24, default 0
controls [ -30 0 0 0 0 0 0 0 0 -30 ]
}
}
1 {
# Expander - remove low-level noise/hiss
label se4
input {
# RMS/peak, 0 to 1, default 0
# Attack time (ms), 1.5 to 400, default 101.125
# Release time (ms), 2 to 800, default 401
# Threshold level (dB), -30 to 0, default 0
# Ratio (1:n), 1 to 20, default 1
# Knee radius (dB), 1 to 10, default 3.25
# Attenuation (dB), -24 to 0, default 0
controls [ 1 101.125 401 -26 10 3.25 0 ]
}
}
2 {
# Compressor
label sc4
input {
# RMS/peak, 0 to 1, default 0
# Attack time (ms), 1.5 to 400, default 101.125
# Release time (ms), 2 to 800, default 401
# Threshold level (dB), -30 to 0, default 0
# Ratio (1:n), 1 to 20, default 1
# Knee radius (dB), 1 to 10, default 3.25
# Makeup gain (dB), 0 to 24, default 0
controls [ 0.9 101.125 401 -10 2 3.25 0 ]
}
}
3 {
# Limiter
label fastLookaheadLimiter
input {
# Input gain (dB), -20 to 20, default 0
# Limit (dB), -20 to 0, default 0
# Release time (s), 0.01 to 2, default 0.5075
controls [ 10 0 0.8 ]
}
}
}
}

# Rate converter set up, dmixplug acts as intermediary between LADSPA plugin
# and dmix, which cannot connect directly
pcm.dmixplug {
type plug slave.pcm dmixer
}
pcm.dmixer {
type asym
playback.pcm {
# See plugin:dmix at http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html
type dmix
ipc_key 5678291
ipc_key_add_uid true
slave {
pcm "hw:1,0"
format S16_LE
rate 44100
channels 2
buffer_size 5000000
}
}
capture.pcm {
type null
}
}
</pre>

← Older revision		Revision as of 14:11, 31 December 2019
Line 119:		Line 119:
	}		}
	</pre>		</pre>
		+	[[Category:Multimedia]]

@@ Line 3: / Line 3: @@
 Turns out that it is possible to do similar enhancements using the LADSPA plugins in ALSA.  As an example, here's the /etc/asound.conf that I use with my radio station Linux server, a Raspberry Pi using a cheap Behringer U-Control UCA 202 digital/analog converter. (Note the use of the hw:1,0 device for output, which corresponds to the USB DAC device.)
-With this config you would direct output to the "radio" device to use the LAPDSPA plugin chain, .i.e., <pre>aplay -D radio some.wav</pre>
+With this config you would direct output to the "radio" device to use the LAPDSPA plugin chain, .i.e., "aplay -D radio some.wav"
 <pre>

@@ Line 8: / Line 8: @@
 <pre>
 # Make USB DAC the default device
 pcm.!default {

@@ Line 1: / Line 1: @@
 I found a great tool for enhancing audio for FM transmission and adding RDS text to the signal, [http://www.stereotool.com/ Stereo Tool].  It's free to use the basic features but it costs $600+ to unlock all of the FM-related features if you want to use them.  In the free version they have a beep tone that goes off every few seconds when you are using unlicensed features.
-Turns out that it is possible to do similar enhancements using the LADSPA plugins in ALSA.  As an example, here's the /etc/asound.conf that I use with my radio station Linux server, a Raspberry Pi using a cheap Behringer U-Control UCA 202 digital/analog converter. (Note the use of the hw:1,0 device for output, which corresponds to the USB DAC device.):
+Turns out that it is possible to do similar enhancements using the LADSPA plugins in ALSA.  As an example, here's the /etc/asound.conf that I use with my radio station Linux server, a Raspberry Pi using a cheap Behringer U-Control UCA 202 digital/analog converter. (Note the use of the hw:1,0 device for output, which corresponds to the USB DAC device.)
 <pre>

@@ Line 94: / Line 94: @@
 # and dmix, which cannot connect directly
 pcm.dmixplug {
-     type plug    slave.pcm dmixer
+     type plug
+}
 pcm.dmixer {

@@ Line 27: / Line 27: @@
 #    "listplugins" to see the list of installed plugins
 #    "analyseplugin <filename>" to see plugin controls
-#    Use "ardour2" to test plugin settings
+#    Use "ardour2" to experiment with plugin settings
 pcm.ladspa {
      type ladspa