Subject: Re: [linux-audio-dev] Another Annoying "How Do I Get Started" Question
From: Paul Davis (pbd_AT_Op.Net)
Date: Wed Jul 11 2001 - 19:29:59 EEST
Greg writes:
>For my purposes it is not a problem. As long as the latency is low enough
>to avoid lip sync problems when processing audio associated with video
>(which means below approximately 30 mSec), I am happy.
and then says:
>Ultimately I would like to know enough to hack the kernel, removing
>everything that is not needed for audio support. I chose Linux simply
>because it is available and has good support; I do not consider it to be
>sacred in any way. As I said, my system will be standalone,
>single-application, audio-only. I believe that the kernel can be seriously
>trimmed and still give me what I need. I just don't know how to do it,
>yet.
You don't need to do anything to the kernel to get the performance you
require, except possibly apply Andrew Morton's low latency patches
(you're sitting right on the borderline of where they might be useful).
>>When you chose to stay in userspace (sacrificing single sample latency)
>>you things get very confortable for you:
>>you write a simple LADSPA host once (eg one that simply loads one/more
>>plugins and then sits in a loop reading from the soundcard, calling the
>>dsp stuff contained in plugins and then output it to the soundcard).
>
>THAT is exactly what I am looking for, then. My first goal is creation or
>adoption of this basic framework with a simple dummy DSP routine in the
>middle. Once the I/O framework is in place, then it is a simple matter of
>plugging-in the appropriate subroutine(s) in place of the dummy routine.
Except that as noted, ecasound and others can already serve as the
basis for your "i/o framework". I would forget about doing your own if
your needs are only in the 30msec range. ecasound can easily handle
that. you can just focus on "floats in; do DSP; floats out". struggling
with OSS or ALSA is a fools game :)
--p ("accomplished fool")
This archive was generated by hypermail 2b28 : Wed Jul 11 2001 - 19:31:14 EEST