[PD] hammerfall and low latency
geiger at xdv.org
Wed Jan 29 20:44:39 CET 2003
On Tue, 28 Jan 2003, Brian Redfern wrote:
> To start with, run ALSA instead of OSS, then what I would do is install
> the rpms from Stanford Universiy's Planet CCRMA site, you need to install
> the rpm that patches your kernel for low latency, then you should get more
> like 2ms latency.
Scheduling is not the problem in this case, so the lowlatency kernel
won't help. Then the ALSA support for pd does not take into account
the peculiarities of the Hammerfall. (BTW, fixing this would be a
useful task ... hint for Kjetil :)
The 2ms latency is a theoretical number which comes from
1/48000 * 64(samples) * 2(input+output) = 2.66.. ms)
Taking this into account the 4 ms measured I/O latency are not at all bad.
Do not forget that we have 64 samples jitter in this measurement too.
(1.45ms at 44kHz, 1.33 at 48).
> On Tue, 28 Jan 2003, smoerk wrote:
> > i just installed a hammerfall 9652 with oss driver and it works with
> > -inchannels 8 -outchannels 8.
> > latency.pd measures 22.6ms latency. how could i get lower latency (<4ms)?
> > does it make sense to start pd with -32bit, if i have a 20bit AD/DA
> > (Fostex VC-8)?
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