[PD-ot] How to massage pd into starting with Alsa on Beagleboard

[Claude Heiland-Allen]

Hi,

This should be on pd-list not pd-ot - Pd usage is off-topic on this 
pd-offtopic list ;) - but replying here too in case you're not on the 
other one (with pd-list as CC: and reply-to:).

Also see this possibly-related thread, which I haven't checked in 
detail, so my reply below may be misinformation:
http://thread.gmane.org/gmane.comp.multimedia.puredata.general/69002
http://thread.gmane.org/gmane.comp.multimedia.puredata.general/69044
http://thread.gmane.org/gmane.comp.multimedia.puredata.general/69045


On 16/07/10 11:15, Edgar Berdahl wrote:
> Furthermore, I can start up a jack audio server as long as I disable the
> audio inputs using -P
> # /usr/bin/jackd -d alsa -d hw:0 -r 44100 -P -p 64

Does "mplayer -ao jack" work?

> However, for the life of me I cannot seem to get Pd to produce sound
> output. For instance, if I try to start Pd using jack
> # pd -jack -noadc test.pd &
> it resets the number of channels to zero, and the CPU usage according to
> top skyrockets to about 95%. To try to start audio, I have to choose
> Media|jack, manually put a check in the box "output device 1", and set
> the channels to 2. Then Pd starts to report, "audio I/O stuck... closing
> audio".

Specifying the number of channels is necessary with -jack with some 
(buggy) Pd versions.  I use "pd -jack -channels 2", you don't need 
"-noadc" because you might want to connect some other jack app (eg 
mplayer) to Pd.

See if "pd -jack -channels 2" with [adc~]==[dac~] in a patch passes 
through "mplayer -ao jack" without any problems, is what I would try.

> It doesn't matter whether I am using "omap3beagle (hardware)" or
> "omap3beagle (plug-in)".

I have to use "plug-in" for my USB soundcard in 24bit mode, as Pd 
doesn't seem to support that sample format natively.

> Does anyone have any other ideas for ways in which I might be able to
> get Pd to produce sound out like mplayer does? I have tried all the
> startup switch combos that immediately came to mind. Could there be some
> inherent reason why Pd will not work if zero audio input channels are
> available?

If Pd is pegging the CPU, maybe something is wrong.  Does the 
beagleboard have a floating point unit (FPU)?  If not, it would 
definitely be better to try an integer-dsp version of Pd (such as 
pda/pd-anywhere/pd-mobile/whatever it's called these days).


Good luck,


Claude