trident (Hoontech 4d Wave NX) dropouts with small buffersize.

trident (Hoontech 4d Wave NX) dropouts with small buffersize.

[Oliver Freyd]

Hello,

I use snd-trident with OSS emulation to access my soundcard.
Music plays nicely, xmms and the like, but after alsa-0.90
or so the linux games began sounding distorted (like tuxracer,
frozen-bubbles, mirrormagic, all SDL-games that my step-son likes...). 
Now I done some more tests to find out where it comes from:

The games use /dev/dsp, and /proc/asound/card0/pcm0p/sub0/hw_params says:
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 22050 (22050/1)
period_size: 512
buffer_size: 1024
tick_time: 10000

well, you hear drop outs, or even bits of sound repeated, sounds weird
( this doesn't happen with the standard OSS trident driver, BTW)
I guess the game people want the buffer size small for low latency...
Seems it is loosing some interrupts or so...

With xmms, buffer_size is 16384, and all is well...

Well, maybe anyone here on this list has an idea what has happened
in the alsa drivers after 0.90 to trigger this bug.

I'm running debian testing, 
alsa-source-1.0.5a-3
kernel 2.4.26
on a dual celeron 300.

Well, maybe this report can be helpful in further development 
of ALSA...

best regards,

    Oliver Freyd



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Re: trident (Hoontech 4d Wave NX) dropouts with small buffersize.

[Takashi Iwai]

At Tue, 5 Oct 2004 22:13:52 +0200,
Oliver Freyd wrote:
> 
> Hello,
> 
> I use snd-trident with OSS emulation to access my soundcard.
> Music plays nicely, xmms and the like, but after alsa-0.90
> or so the linux games began sounding distorted (like tuxracer,
> frozen-bubbles, mirrormagic, all SDL-games that my step-son likes...). 
> Now I done some more tests to find out where it comes from:
> 
> The games use /dev/dsp, and /proc/asound/card0/pcm0p/sub0/hw_params says:
> access: RW_INTERLEAVED
> format: S16_LE
> subformat: STD
> channels: 2
> rate: 22050 (22050/1)
> period_size: 512
> buffer_size: 1024
> tick_time: 10000
> 
> well, you hear drop outs, or even bits of sound repeated, sounds weird
> ( this doesn't happen with the standard OSS trident driver, BTW)
> I guess the game people want the buffer size small for low latency...
> Seems it is loosing some interrupts or so...
> 
> With xmms, buffer_size is 16384, and all is well...
> 
> Well, maybe anyone here on this list has an idea what has happened
> in the alsa drivers after 0.90 to trigger this bug.

No idea yet, but could you check whether this happens with ALSA native
apps?  For example, you can run aplay with --buffer-size and
--period-size options.  Pass above values to these options and see
whether the playback works.


> I'm running debian testing, 
> alsa-source-1.0.5a-3

It's old :)


Takashi


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Re: trident (Hoontech 4d Wave NX) dropouts with small buffersize.

[Oliver Freyd]

Hello Takashi,

thanks for your reply!

On Thu, Oct 07, 2004 at 03:04:34PM +0200, Takashi Iwai wrote:
 
> No idea yet, but could you check whether this happens with ALSA native
> apps?  For example, you can run aplay with --buffer-size and
> --period-size options.  Pass above values to these options and see
> whether the playback works.
> 

Yes, I've tried that now, if play some sound with aplay, without
--buffer-size, it works normal. If I use --period-size 512 and
buffer-size 1024, I get that broken sound. Also with period-size 1024 and 
buffer-size 2048, I think. Only if I use a buffer-size > 2* period-size
if works ok.

> 
> > I'm running debian testing, 
> > alsa-source-1.0.5a-3
> 
> It's old :)
> 
This weekend I'll try to compile the newest alsa-sources :-)

Thanks for your help,

    Oliver



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Re: trident (Hoontech 4d Wave NX) dropouts with small buffersize.

[Takashi Iwai]

At Fri, 8 Oct 2004 09:15:06 +0200,
Oliver Freyd wrote:
> 
> Hello Takashi,
> 
> thanks for your reply!
> 
> On Thu, Oct 07, 2004 at 03:04:34PM +0200, Takashi Iwai wrote:
>  
> > No idea yet, but could you check whether this happens with ALSA native
> > apps?  For example, you can run aplay with --buffer-size and
> > --period-size options.  Pass above values to these options and see
> > whether the playback works.
> > 
> 
> Yes, I've tried that now, if play some sound with aplay, without
> --buffer-size, it works normal. If I use --period-size 512 and
> buffer-size 1024, I get that broken sound. Also with period-size 1024 and 
> buffer-size 2048, I think. Only if I use a buffer-size > 2* period-size
> if works ok.

Hmm, how about the bigger period & buffer sizes?  Try both periods=2
and other cases.

The trident driver handles differently when period_size =
buffer_size/2.  If period_size != buffer_size/2, it allocates an extra
voice for the interrupt source.  So, if the bug occurs only with
periods = 2, it narrows the buggy part.


Takashi


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Re: trident (Hoontech 4d Wave NX) dropouts with small buffersize.

[Oliver Freyd]

On Fri, Oct 08, 2004 at 06:39:50PM +0200, Takashi Iwai wrote:
 
> Hmm, how about the bigger period & buffer sizes?  Try both periods=2
> and other cases.
> 
> The trident driver handles differently when period_size =
> buffer_size/2.  If period_size != buffer_size/2, it allocates an extra
> voice for the interrupt source.  So, if the bug occurs only with
> periods = 2, it narrows the buggy part.
> 
Hello,

I've tried that, I think your idea is right. 
The bug occurs when period_size = buffer_size/2 , also for bigger periods
like 2048 or 4096. Then you can hear that some buffers are repeated,
the soundcard plays them again. If you decrease period_size (even only by 1)
it works nicely. If you increase, you get buffer underruns (aplay detects
them). 

So it seems you have an idea of where the bug could be :-)

If you tell me what else I could do to narrow down the problem,
I'm happy to help you!

  best regards,

    Oliver



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Re: trident (Hoontech 4d Wave NX) dropouts with small buffersize.

[Takashi Iwai]

[-- Attachment #1: Type: text/plain, Size: 1164 bytes --]

At Sat, 9 Oct 2004 20:41:35 +0200,
Oliver Freyd wrote:
> 
> On Fri, Oct 08, 2004 at 06:39:50PM +0200, Takashi Iwai wrote:
>  
> > Hmm, how about the bigger period & buffer sizes?  Try both periods=2
> > and other cases.
> > 
> > The trident driver handles differently when period_size =
> > buffer_size/2.  If period_size != buffer_size/2, it allocates an extra
> > voice for the interrupt source.  So, if the bug occurs only with
> > periods = 2, it narrows the buggy part.
> > 
> Hello,
> 
> I've tried that, I think your idea is right. 
> The bug occurs when period_size = buffer_size/2 , also for bigger periods
> like 2048 or 4096. Then you can hear that some buffers are repeated,
> the soundcard plays them again. If you decrease period_size (even only by 1)
> it works nicely. If you increase, you get buffer underruns (aplay detects
> them). 
> 
> So it seems you have an idea of where the bug could be :-)
> 
> If you tell me what else I could do to narrow down the problem,
> I'm happy to help you!

Ok, to be sure, please try the attached patch.
This will make the driver ignoring the check of 2 periods and always
allocatint an extra voice.


Takashi

[-- Attachment #2: Type: text/plain, Size: 725 bytes --]

Index: alsa-kernel/pci/trident/trident_main.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/pci/trident/trident_main.c,v
retrieving revision 1.59
diff -u -r1.59 trident_main.c
--- alsa-kernel/pci/trident/trident_main.c	30 Jul 2004 12:44:59 -0000	1.59
+++ alsa-kernel/pci/trident/trident_main.c	11 Oct 2004 15:24:30 -0000
@@ -814,7 +814,7 @@
 
 	/* voice management */
 
-	if (params_buffer_size(hw_params) / 2 != params_period_size(hw_params)) {
+	if (1 /*params_buffer_size(hw_params) / 2 != params_period_size(hw_params)*/) {
 		if (evoice == NULL) {
 			evoice = snd_trident_alloc_voice(trident, SNDRV_TRIDENT_VOICE_TYPE_PCM, 0, 0);
 			if (evoice == NULL)

Re: trident (Hoontech 4d Wave NX) dropouts with small buffersize.

[Oliver Freyd]

On Mon, Oct 11, 2004 at 05:27:32PM +0200, Takashi Iwai wrote:
 
> Ok, to be sure, please try the attached patch.
> This will make the driver ignoring the check of 2 periods and always
> allocatint an extra voice.
> 
> 
> Takashi

Hello Takashi,

I've applied your patch. It works great, no more missed buffers and dropouts
when buffer_size=2*period (tried with aplay).
The games sound nicely, too!!

So your idea was correct. Only thing I don't quite understand is why is there
an extra voice to generate interrupts in the first place, and why not in that
special case. But you'll know why anyway...

well, that's it for now,

   best regards, Oliver


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