Posts: 2
Joined: Thu Aug 02, 2018 11:36 am

audio delay device - Echo - up to 2 seconds

Fri Aug 03, 2018 10:32 am

Hi there,
I need some help for my art project and I hope you guys can help a newbie like me.
I want to make an audio delay device that imitates a mountain echo. A device with a microphone that plays back some audio after about 2 seconds. I was thinking to build something with the arduino but I guess it would be better to try it with a RPI because of the memory space.

Am I completely wrong? In my head it doesn't sound so complicated.
...a microphone that records the audio and stores it and plays it back after 2 seconds...

Is that possible to do with a raspberry pi? I'm really a greenhorn in this field and I would need some starting help.
I would be happy for any suggestions or ideas.

Posts: 100
Joined: Wed Oct 24, 2012 9:15 pm
Location: Cheltenham, UK

Re: audio delay device - Echo - up to 2 seconds

Fri Aug 03, 2018 6:41 pm

Given my minor break through using a Pi to emulated Caller ID I have a little experience using a USB sound dongle with the Pi. I used to make my living bluffing folk I knew enough of the C programming language to get paid for it. If you don't program yet it will be a bit of an up hill ride.

If you have functional C skills and you fancy a stab at it there are loads of examples of reading and writing blocks of 'sound' data using the ALSA input/output functions for to/from a USB sound dongle. You'll need a dongle because the Pi only supports sound output. I've got a C-Media dongle and it only provides mono microphone but stereo output. This makes it a bit of a fiddle to use because microphone data will be single words while the stereo output will need left and right words packed in pairs making the output buffers twice as big as the input buffer so needing a bit of re-packing.

I have to add the reference media on the ALSA library functions is a bit terse but there are limited tutorials for sound board/dongle setup, read/write data and close on the web which is what I used. You will also need to install the ALSA support libraries into the Pi.
Share and Enjoy.

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