Subject: Re: [linux-audio-dev] Reverbs... and the usual whinings
From: Tommi Ilmonen (tilmonen_AT_cc.hut.fi)
Date: Sat Sep 23 2000 - 18:38:31 EEST
On Sat, 23 Sep 2000, Benno Senoner wrote:
> On Sat, 23 Sep 2000, Juhana Sadeharju wrote:
> >
> > The way I get always dropouts is to delete a large file (20 Mbytes do fine)
> > or directory. I'm not sure what are the changes when (i) soft-RT, and then
> > (ii) low-latency patch are added to the recorder. Could there be problems
> > even our A/D-to-disk buffer would be 16 Mbytes?
> >
>
> no the low-latency patch alone does not ensure a drop-out free operation.
> my experience says:
> - use a 2 thread approach (audio thread, disk thread)
> - you must use SCHED_FIFO for at least the audio thread
> - use a lock-free approach to pass data back and forth between audio and disk
> thread
Whether you need locks really depends on your app. In the cases I usually
deal with over/underrunning file IO is as serious error as having the same
happen to audio devices (=fatal error).
There is a LGPL C++ class (DI_AudioFileThreaded) that implement threaded
audio files in the DIVAIO library:
http://www.tml.hut.fi/~tilmonen/diva/
The DIVA libraries are about as compact and stand-alone as it gets.
The usual disclaimers: The API is fairly ok altough the internals are
still a mess. Plus the code is semi-experimental.
Hope this also helps....
Tommi Ilmonen Researcher
>=> http://www.hut.fi/u/tilmonen/
Linux/IRIX audio: Mustajuuri
>=> http://www.tml.hut.fi/~tilmonen/mustajuuri/
3D audio: DIVA
>=> http://www.tml.hut.fi/Research/DIVA/
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