Tinkering section again
Suggest doing an update of speexdsp & speex with libasound2-plugins as in
But not essential.
Install is pretty easy, but you need to make sure the sink and source come from the same clock source as clock drift will likely render it useless.
I have tried the pulseaudio webrtc EC several times which is supposed to cope with clock drift but on Arm it doesn’t seem to work at all.
Also strangely the echo of the alsaplugin of speex doesn’t seem to work but in the following this repo will use the speexdsp libs and it will work extremely well? Dunno…
But your soundcard make sure it plays and records such as a usb soundcard or some of the mic hats with a soundcard chip (gets a bit confusing as some hats have seperate on board clocks for dac and adc).
So cheap USB soundcard or something like the respeaker 2mic.
We are going to run from where we install this will just install in %HOME install where you wish
git clone https://github.com/voice-engine/ec.git
cd ec
make
./ec -h
should give you the help info of ec and show its installed.
Ec uses a fifo file in /tmp for audio rather than a source so again just install.
This utility will install rather than just in the repo directory.
cd ..
git clone https://github.com/voice-engine/alsa_plugin_fifo.git
cd alsa_plugin_fifo
make && sudo make install
https://raw.githubusercontent.com/voice-engine/ec/master/asound.conf copy to /etc/asound.conf
pcm.!default {
type asym
playback.pcm "eci"
capture.pcm "eco"
}
pcm.eci {
type plug
slave {
format S16_LE
rate 16000
channels 1
pcm {
type file
slave.pcm null
file "/tmp/ec.input"
format "raw"
}
}
}
pcm.eco {
type plug
slave.pcm {
type fifo
infile "/tmp/ec.output"
rate 16000
format S16_LE
channels 2
}
}
So this sets to fifo files ec-in and ec-out as your playback and capture defaults.
Go back to ec
cd ..
cd ec
./ec -i plughw:2 -o plughw:2 -d 20
The -d 20 is to try and compensate for your latency which really should of mentioned earlier as you can use alsabat with –roundtriplatency to measure latency from output to mic capture.
The repo states its 200 msec but to be honest it seems to be much less but alsa the redirection of ec may also add to this but seems impossible to measure with EC running so test your hardware first.
You need to open another terminal and aplay a wav.
wget https://file-examples-com.github.io/uploads/2017/11/file_example_WAV_10MG.wav
aplay file_example_WAV_10MG.wav
EC will start on playing media and at end of file stop.
So aplay an example wav to the default playback device and Enable AEC will show.
When it ends you will get something like
playback filled 256 bytes zero
No playback, bypass AEC
So what is happening is EC is listening on the mic and trying to subtract the playing wav from that fifo file eci and places the result in eco which we need to record from.
So just to test we will open up another terminal and start a recording before we play.
arecord -r16000 -fS16_LE -c1 ec-rec.wav
EC is already running so go back to the aplay console and play the example wav again.
Then ctrl+c to stop the recording in the arecord terminal.
Now you prob have found the one quirk that EC has that on the end of recording EC ends with
-bash: playback: command not found
So we need to fix that with a alsa loopback device which we need to modprobe.
So this gets the alsa index it will on boot each we enable we are going to add it to the modules to load on boot.
sudo nano /etc/modules and add snd-aloop to that file save and reboot.
you should see something like
pi@raspberrypi:~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 0: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 1: b1 [bcm2835 HDMI 1], device 0: bcm2835 HDMI 1 [bcm2835 HDMI 1]
Subdevices: 4/4
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
card 2: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 H eadphones]
Subdevices: 4/4
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
card 3: Dongle [VIA USB Dongle], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
So what we will do is pipe the arecord into one side of the loopback a sink and the other side will be our source.
So in a terminal run ec again you may find the card index has changed ./ec -i plughw:3 -o plughw:3 -d 20
Pipe arecord into the loopback arecord -Deco -r16000 -fS16_LE -c1 | aplay -Dplughw:0,0,0 so its constantly recording.
But we will now use the other side as a source to record from arecord -Dplughw:0,1,0 -r16000 -fS16_LE ec-rec.wav
Now you prob want to edit the /etc/asound.conf and make the loopback on -Dplughw:0,1,0 the default capture device.
Or you may want to use that as a pcm slave for speex AGC but will let you decide on how you edit and channge /etc/asound.conf.
You should now find when Rhasspy plays or records on the default devices EC will continue.
You will have to create a boot script or service and run EC and pipe through the loopback but at least you know how to get EC running.
There is ec_hw in the repo and it would also of been compiled on make never did work it out maybe you can.
It should be called Echo Attenuation but you should find its more than capable of allowing barge in that was extremely problematic before.