Re: [linux-audio-dev] SOUND DRIVER FOR RTLINUX USING SOUND BLASTER

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Subject: Re: [linux-audio-dev] SOUND DRIVER FOR RTLINUX USING SOUND BLASTER
From: David Olofson (david_AT_gardena.net)
Date: Sun May 14 2000 - 19:39:49 EEST


On Fri, 05 May 2000, alvaro wrote:
> I would like to recognize voice in real time. I thought that RTLinux
> could be a good chance.

If you need better than 2-3 ms latency, you need RTL; if not, you'll
be fine with Mingo's lowlatency patches or a (pre-) 2.4 kernel.
Sticking with user space makes things a whole lot easier, as you can
use normal drivers such as ALSA or the kernel drivers ("OSS/Free").

> ¿Could you tell me what type of sound driver
> should I use in order to use it in RTLinux?.

There are no sound card drivers for RTL, except for a few individual
hacks (mostly for embeded applications), such as the example es1370
driver that comes with my Driver Programming Interface (DPI). Have a
look at

        http://www.angelfire.com/or/audiality/download.html

but beware; I haven't touched the code for ages, and AFAIK, it won't
compile with any recent RTL versions. It also has some more or less
serious bugs lurking around...

> Since I would like to make
> programs in C using the driver ¿How could I find some documentation of
> how to use this driver? ¿Where could I find the driver?. I mean I need
> all about the driver.

Well, where to find the documentation depends on what chipset there
is on the card. I'm not sure if you can download interesting stuff
from Creative's web site, but you could have look... I think the ALSA
project ( http://www.alsa-project.org ) has some documents.

Anyway, the easiest way is probably to port an existing Linux
(OSS/Free) driver, and in that case, you shouldn't need much more
documentation than the source. Porting ALSA would probably be more
efficient if you need to port more than one driver (modular, nice
design; most of the code you need to change is probably in the core
rather than repeated in every single card driver), but it's more
work for a "single driver hack".

You can have a look at my DPI (above) for some ideas on how to
translate the usual Linux "API" constructs into something RTL
compatible, but keep in mind that the code isn't up-to-date, and
that it isn't exactly production quality code.

//David

.- M u C o S --------------------------------. .- David Olofson ------.
| A Free/Open Multimedia | | Audio Hacker |
| Plugin and Integration Standard | | Linux Advocate |
`------------> http://www.linuxdj.com/mucos -' | Open Source Advocate |
.- A u d i a l i t y ------------------------. | Singer |
| Rock Solid Low Latency Signal Processing | | Songwriter |
`---> http://www.angelfire.com/or/audiality -' `-> david_AT_linuxdj.com -'


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