Recording at 8 kHZ mono

[flatmax]

Some people would like to record at 8 kHz sample rates.
To do this use the following command :

Code: Select all

arecord -D"plug:'dsnoop:RATE=8000'" /tmp/test.wav

[namdoog]

Some people would like to record at 8 kHz sample rates.
To do this use the following command :

Code: Select all

arecord -D"plug:'dsnoop:RATE=8000'" /tmp/test.wav

Just curious: This also seems to work:

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arecord -r 8000 -f S16_LE -c 2 /tmp/test.wav

(Modelled after the arecord command in your test script.)

Is the result different? What does the dsnoop device selection do for us here? (Forgive the newbie inquiry).

[flatmax]

Hi there,

Since updaing the driver, I have enabled the hardware to record natively at 8000 Hz. Previously (before enabling) we had to use the ALSA dsnoop plugin to resample for us.
Thanks for pointing out this upgrade !

Matt

[brett]

Hi not sure what im doing wrong. i have a raspberry pi3 with the latest jessie, do i need a modified asoundrc file, or have i messed up the alsamixer settings




pi@raspberrypi:~ $ arecord -D"plug:'dsnoop:RATE=8000'" /tmp/ttest.wav
ALSA lib pcm_direct.c:896:(snd1_pcm_direct_initialize_slave) slave plugin does not support mmap interleaved or mmap noninterleaved access
ALSA lib pcm_dsnoop.c:629:(snd_pcm_dsnoop_open) unable to initialize slave
arecord: main:722: audio open error: Invalid argument


thank-you

[brett]

hi i tried another sd card i had with all the pulseaudio removed, it worked with your... arecord -D"plug:'dsnoop:RATE=8000'" /tmp/test.wav. Is there a way that the asoundrc file, could be written to do this automaticaly , I am trying to get pocketsphinx to work it doesnt like dsnoop , as it wont do 8000khz any hlp would be appreiciated.

[flatmax]

Hey there,

I think I have an idea for you to record 8 kHZ mono. The dsnoop plug does everything and I am not sure if there is extra cost involved. MY idea is to use an .asoundrc file in your home directory to redefine the default device to let you do either stereo or mono.

I have only tested this for playback, could you test it with recording ? It is setup to automatically use the standard sound card (assuming your audioinjector card is card 0). Also the latest audioinjector stereo Pi card supports 8 kHZ natively.

With the .asoundrc file below :
This should work : aplay monoTrack.wav
This should work : aplay stereoTrack.wav

I haven't tested recording... can you let me know if it works ?

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pcm.!default 1or2ch

ctl.!default {
	type hw
	card 0
}

pcm.1or2ch {
	  type route
	  slave.pcm "hw:0"
	  slave.channels 2
	  ttable.0.0 1
	  ttable.1.1 1
}

thanks
Matt

[brett]

Thankyou for your help, i did not need the asoundrc, i ended up leaving my asoundrc blank, and the card started to work, how i wanted it too, thank-you again