Another forgotten site

i forgot i was uploading to another site....

all ship-shape here now

new track unveiled for the end of time

first mix and a psychedelic video....no name yet....

Raspberry Pi usb sound into pure data- the Griffin Imic

the griffin imic - get it here

After testing a few usb sound cards i settled on this one giving the best results for the bat-box project (and the set up described here is the one i used for this specific project)

 i used a 50 sec buffer size and the sound set at 2250hz. This seemed to work really well, i didn't really investigate getting the sound up to 44100hz,(i spent a day trying it with not much success) because 22.5kz is  stable, and good enough sound quality, obviously this is something to investigate more when not in the middle of getting a project going.

The imic is really stable when running, although there are a few random issues. 

the imic doesn't need setting through the terminal alsamixer each time when using pure-data extended, but the first time you use it (and if something goes wrong) do this…..

-open terminal

- and type in  (stuff between quotes, don't include quote marks when typing)

"alsamixer"

-f6 key lets you choose the card

-f5 lets you change the mic in , sound out ,treble and bass setting

press escape to leave the alsamixer

Pure-data extend generally flashes a red  warning as it boots up warning of a problem  with the audio,  "audio I/O error" -  ignore this as it doesn't stop or crash the audio.

the imic really likes the top usb-port, moving it from here can sometimes cause problems. If you're using more than two usb items (which you would do as you need a mouse and keyboard at least) invest in a usb powered hub -the best one i found was from the mod my pi website, remember as in all periphals working with the pi,  not all powered hubs are equal - some work better than others). 

The imic can go down if you're using too much power, for instance when using with an arduino, but once the program is optimised it will run with no problem each time. (-run without a gui , take bits out of the program to make it more efficient).A good indicator is the green cpu monitor in the corner of the pi, you want to leave a bit of a gap at the top so its not totally green, when it goes totally green thats when the sound card is in danger of going down.

Also with the imic you get one shot per boot, if it goes down it wont work again, if you close pure-data extended and don't reboot the next time you open pd-extended the imic wont work, so each time you close pd-extended you have to reboot in order to use it again.

Sometimes after p-d extended is started but before the pure-data patch is opened the imic decides to not work, the easy fix solution is just to restart the pi, and generally it works. If it carries on, re open alsamixer and reset the sound card…-this might help….

...... also turning the pi off for a day then coming back to it has weirdly worked a few times.

Getting pd to work well on a raspberry pi 2

A few tips to get pd working well....

- open terminal

- then type (stuff between quotes, don't include quote marks when typing)

"sudo nano /etc/security/limits.conf"

-and then at the bottom of the document add (type in)

"* - rtprio 99

 * - memlock 1000000000"

-then save.


The sound settings here work realy well with the Griffin Imic

-start pd
-on title bar go to media > preference > startup
-add (type in) the following flag in the startup flag field 

"-rt -alsa -audiobuf 50"

- the bring up sound settings and change

"audio buffer 50ms

sampling 22050kz"

Miller Puckette tells it like it is


Miller Puckette - Intro to Raspberry Pi from Alexander Matthews on Vimeo.

Miller Puckette - Raspberry Pi and the SD Card Storage for Pure Data from Alexander Matthews on Vimeo.

Miller Puckette - Pure Data on the Raspberry Pi from Alexander Matthews on Vimeo.

Refining the Raspberry Pi - batteries

the batteries used in the bat box are these...

Anker Astro 5600mAh

They are pretty good, they can power an arduino, sound card and a raspberry pi (overclocked to turbo) for over four hours....

Raspberry Pi - Vocal Migrations

Working with the artist Kathy Hinde, I have been developing the software for the bat box element of her project Vocal Migration. The bat-box is a stand-alone vocal sampler run on a raspberry pi, using a ultra-sonic sensor to modulate the sample. If you want to find out more about the project check here. 

The box is made up of a raspberry pi, run from a battery with a arduino board giving controls from knobs and buttons, and also modulating the sound output from a ultra-sonic sensor. Sound in is provided by a sound card, and a powered vocal mic and sound out is via a small powers speaker.