Quote:> I need to develop a real time audio signal processing application.
What exactly should it do? Read samples from the sound card,
lowpass-pass filter them or so and play them again? With what latency
should that happen? Also consider that sound cards have a small buffer
on the card itself (10 ms or so?).
Quote:> I'm trying to get clear about the os I should use for this. As far
> as I know I should be looking for an os that some how guarantees the
> time intervals between events.
What do you mean by "events"?
Quote:> My software must record/process/play audio samples from several
> channels at 48kHz rate. I already know that windows does not
> guarantee the time intervals so I am thinking about other os. Is all
> this possible under linux?
With Linux's so-called realtime scheduler (man sched_setscheduler),
you should get latencies less than 10 ms in 99.9% of all cases or
so. Typically, latencies are even less than 1 ms. But all that depends
on the kernel (look for "low latency patch" and "preemptive kernel" to
improve latency), the hardware and your load (disk access, network
access). So you have to try it out for yourself and see whether it
fits your needs.
- Linux does not _guarantee_ any latency.
So you need much testing and recovery from overflow/underflow in the
very seldom cases it happens.
- Scheduling granularity is 10 ms in kernel 2.4.x, e.g. nanosleep(15ms)
awakens the process 15-20 ms after it's called. There is a patch to
improve scheduling granularity to 1 ms (or better, if you want to
There are realtime extensions for Linux, but I have never tried one.
Quote:> The hardware I have is a professional multichannel sound card of
> 24bits and 96kHz sample rate.
Is there a driver for linux?
Does it work with full duplex?
Does it work properly?
Dipl.-Phys. Moritz Franosch