[PlanetCCRMA] Re: HDSP 9632 with PD under Linux/Shortening Delays using PD...

derek holzer derek@x-i.net
Mon Jan 26 15:46:01 2004

Hi Melissa,

Melissa Corso wrote:
> I have successfully installed PD and used it with an audiocard (HDSP 
9632) under Windows XP. However when using windows XP  there is a 
substantial delay in the output.

You will probably want to adjust your -audiobuf settings. PD has a *lot* 
of startup arguments [type pd --help to see them all], and one of them 
controls the audiobuffer size. With an RME card, you should be able to 
enter very small numbers. Start with 50 [ms] and see what happens. If 
your audio stream breaks up, you set it too low. Once you have the right 
number, you can save yourself the trouble of typing it again and again 
by making a .bat script [under windoze] or a .pdrc file [under linux] 
which contains all your settings.

If shortening the actual DSP delay [irregardless of soundcard latency] 
is what you are after, then you should investigate the -blocksize 
argument, which sets the DSP sample blocksize. There is also an object 
in PD which sets the blocksize for a particular section of your patch: 
[block~] I think... Read the helpfile for this object for more info.

> When I use linux, as soon as PD starts up I get this message and the audio card is no longer recognized (no audio output). 
> using non-interleaved audio input
> Sample width set to 4 bytes
> ALSA: set input channels to 4
> snd_pcm_hw_params_set_access (output): Invalid argument
> using non-interleaved audio
> alsa: set output channels to 4
> audio I/O stuck... closing audio

You are correct that PD tends to perform quite well under a lean Linux 
system. However, PD and ALSA have had a strange divorce proceeding 
lately, as ALSA has taken a new direction and PD hasn't caught up with 
it yet ;-) Plenty of folks have said they can't run PD with ALSA at all. 
Probably better not to use ALSA, but get it running with Jack or with 
OSS-emulation for the time being. Ask around [Planet CCRMA list, ALSA 
List] if you need more info on this.

Good luck,

derek holzer ::: http://www.umatic.nl
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