[PD] pd in ubuntu 8.04: pd hijacks alsa?

IOhannes m zmoelnig zmoelnig at iem.at
Mon Dec 6 09:21:24 CET 2010


On 2010-12-05 22:34, Aaron L. wrote:
> This is somewhat of a complete newb issue so I apologize up front for
> that.......
> 
> However, it seems that I cannot use pdextended and watch a youtube video at
> the same time (the youtube vid is a pd tutorial).
> 
> Here's what it's starting with:
> 
>  pasuspender -- /usr/bin/pdextended -alsa %F
> 
> Is it absolutely necessary to start pd with 'pasuspender'?
> 
> When I don't (i.e. start it like this:  '/usr/bin/pdextended -alsa' ), I get
> a bunch of 'device or resource busy' messages in the terminal and I don't
> get any audio when doing the whold testtone thing).
> 
> Is there any way around this?


well, this is exactly the way how alsa is supposed to work:
- only one application can access a (hardware) device at any point

pulseaudio is a way to circumvent this limitation.
running Pd in pasuspender, effectively disables pulseaudio including all
it's features.


luckily there are ways around that.

- use pulseaudio (not a good option, as Pd currently doesn't support it
:-(; btw, pa is geared towards the ordinary consumer multimedia desktop
where people would like to watch their youtube videos and at the same
time listen to the latest p!nk smash hit; Pd is not really targeted
towards that marketm, hence pa is not done yet)

- use alsa's "dmix" interface; "dmix" is a virtual device that allows
several applications to send their audio output to the same hardware
device (without the applications even knowing of it). i'm not 100% sure
whether you can actually access this from within Pd....

- use "jack". now you can think of jack as "pulseaudio for pros", it
allows to route the output of one process to the input of another
process (or more); "process" can be both hardware (your soundcard) or
software (Pd, your browser,...).
there are also ways to make alsa-only applications (e.g. your browser)
use a pseudo alsa device that really sends all audio to jack (thus the
application need not be aware of jack at all)


madt
IOhannes

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