RE: [linux-audio-dev] 1.5 ms latency possible?

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Subject: RE: [linux-audio-dev] 1.5 ms latency possible?
From: David Seymour (David_AT_benchmarkmedia.com)
Date: Thu Jan 02 2003 - 17:21:46 EET

Would it be safe to say that trying to lower latency within the system for
monitoring purposes is simply a waste of horsepower given the availablilty
of I/O cards with routing DSP build into them? I know LYNX and RME have
cards that will do this.

David Seymour
Benchmark Media Systems
800-262-4675
www.benchmarkmedia.com

-----Original Message-----
From: David Olofson [mailto:david_AT_olofson.net]
Sent: Tuesday, December 31, 2002 5:35 PM
To: linux-audio-dev_AT_music.columbia.edu
Subject: Re: [linux-audio-dev] 1.5 ms latency possible?

On Tuesday 31 December 2002 23.24, Anders Torger wrote:
[...]
> I've thought about RTLinux actually, but it is simply too much
> work, porting drivers to start with...

You can probably get away with using normal drivers (OSS or ALSA) in
mmap() mode, and hooking the interrupt with an RTLinux or RTAI ISR.
Start up the I/O from user space as usual, and then divide the IRQ
period into the number of fragments you need, using an RTL or RTAI
periodic thread. Just keep in mind that PCI cards generally have a 64
byte PCI burst size limit, so going below that won't work.

//David Olofson - Programmer, Composer, Open Source Advocate

.- The Return of Audiality! --------------------------------.
| Free/Open Source Audio Engine for use in Games or Studio. |
| RT and off-line synth. Scripting. Sample accurate timing. |
`---------------------------> http://olofson.net/audiality -'
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