We're running Pd 0.43 on a Gumstix Overo Airstorm with Cortex A8
architecture, using Linaro 12.02 distribution (which is based on
Ubuntu 11.10 )
Pd seems to be working but audio input and output is displaying
strange behaviours and processing artifacts.
Simple osc~ objects play their tones at half pitch, and when we run
audio into it in realtime ( connecting adc~ direct to dac~ ) we
experience both lower pitch and time granulation. CPU usage reads less
Samplerate is 44100 and blocksize is currently at 1024 (anything lower
than this creates crackling, and causes CPU usage to jump to 80%)
Does anyone here know if this CPU is just unable to process floating
point data at the speed required by Pd, or whether there are some
processing settings/ priority settings or a different kind of kernel
that would allow Pd to run correctly on this platform.
We're surprised it's not working as we know PDlib runs fine on the
iPhone for instance. We've already successfully run PDa on a Gumstix
Verdex but really want to move to full Pd to get around the
limitations of PDa.
any thoughts or suggestion welcome,
we're getting desperate!
follow me : @ofcircumstance
From: Tim Redfern <gumstix@ec...> - 2012-03-05 15:49:57
further to this - (Duncan and I are working together)
When a usb audio interface is used, the audio works perfectly in puredata on
airstorm-linaro for playback and capture
There is some kind of incompatibility between the overo audio driver and pd.
The overo audio driver is working fine with aplay.
We are using alsa oss emulation as alsa itself isn't working with pd
although pd supports alsa.
With oss emulation, the audio has artefacts and pd is using a very large
amount of cpu (~80%).
If the 'block size' is increased (i.e. the amount of audio samples being
processed at a time) cpu usage decreases drastically (to <%2) and the audio
output becomes smooth (although at the wrong pitch). audio input however is
still distorted/ granulated.
I wonder is anyone knows what the difference is with the TPS65950 audio
driver, whether it can be reset or reconfigured in some way...
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