Re: problems with ALSA and SDL

Re: problems with ALSA and SDL

[Francesco Abbate]

It seems that I'm the only guy who is trying to use an AWE64
without OSS emulation.

I've tried "asfxload" with my AWE64 and it doesn't work. Probably
this is due to my ignorance since I've only a basic understanding
of PCM playback and none about MIDI (with ALSA I mean).

The question is the following :
I load all the ALSA modules, both for the sequencer and PCM.
In fact the ouput of "pmidi -l" gives:
-----------------
 Port     Client name                       Port name
 64:0     Rawmidi 0 - MPU-401 (UART) 0-0    MPU-401 (UART) 0-0
 65:0     Emu8000 WaveTable                 Emu8000 Port 0
 65:1     Emu8000 WaveTable                 Emu8000 Port 1
 65:2     Emu8000 WaveTable                 Emu8000 Port 2
 65:3     Emu8000 WaveTable                 Emu8000 Port 3
 66:0     OPL3 FM synth                     OPL3 FM Port
-----------------
Then, when I try to load the soundfont with

./asfxload synthgm.sbk

I get :
No Emux synth hwdep device is found.

I've verified with the source code that the problem is at
the very beginning when the program call

snd_hwdep_open(&hwdep, name, 0)

I've tried with -D "hw:0,2" but the result is the same.
I've also verified that a basic "sequencer program" works
but just without playing any sound, of course.

I didn't like to bother the devel ML with such kind of problems
but there is no documentation about "sound font loading without
OSS emulation".
-- 
Francesco Abbate


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problems with ALSA and SDL

[Francesco Abbate]

Hello everyone,

I've recently switched to the 2.6.x kernel and I've decided to
switch to ALSA too.

I've enabled ALSA into the kernel *without* OSS emulation and
I've began to manage to get things works.

Now I can say that everything works with the exception of sfxload
(the program that load the soundfont for the AWE32/64) which still
require OSS (emulated or not). But this is not the problem I want
to discuss here.

One of the major problem I've encountered with ALSA is that it *seems*
to be very CPU intensive.
In fact I've compiled the SDL library with ALSA and I've discovered that
my CPU is not fast enough to run the game when the sound is anabled.
The CPU get a very heavy load and the sound is badly scattered (buffer
underrun I suppose).
The strange thing is that I've tried quite simple game that previously
works very well with OSS. My CPU is also not so bad because it is an
AMD K6 MMX 200 MHz.
I've given a glance to the ALSA code of SDL and it seems to be plain
PCM playback code without any sofistication.
At beginning I was thinking that the problem was the use of "plughw"
instead of "hw" but I've tried with "hw" and the situation is still
the same.

So the question is :
is ALSA much more CPU intensive then OSS or there is some
technical problem which cause this effect ?
why there is such difference with OSS ?

I hope I've not to switch back to OSS simply because I cannot run
some *simple* games.

-- 
Francesco Abbate
-- 
Francesco Abbate


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Re: problems with ALSA and SDL

[Michel Dänzer]

On Tue, 2004-01-27 at 19:01, Francesco Abbate wrote:
> 
> One of the major problem I've encountered with ALSA is that it *seems*
> to be very CPU intensive.
> In fact I've compiled the SDL library with ALSA and I've discovered that
> my CPU is not fast enough to run the game when the sound is anabled.
> The CPU get a very heavy load and the sound is badly scattered (buffer
> underrun I suppose).

This is an SDL 1.2.6 problem which has been fixed in CVS, see
http://www.libsdl.org/pipermail/sdl/2003-December/058752.html and
http://www.libsdl.org/pipermail/sdl/2004-January/058861.html .


-- 
Earthling Michel Dänzer      |     Debian (powerpc), X and DRI developer
Libre software enthusiast    |   http://svcs.affero.net/rm.php?r=daenzer



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Re: problems with ALSA and SDL

[Jaroslav Kysela]

On Tue, 27 Jan 2004, Francesco Abbate wrote:

> So the question is :
> is ALSA much more CPU intensive then OSS or there is some
> technical problem which cause this effect ?

I suspect that there might be some trouble with SDL code. Can you try our 
tools (aplay/arecord) to verify it?

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs


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