HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Mark Knecht]

Hi,
   I have a pretty frustrating problem with my Alsa setup. Right now I'm
just looking for guidance about what's messed up and how I might get it
fixed. I'm not sure if it's a driver issue, an Alsa issue, or a hardware
issue. I have not yet found anyone else that has this exact set of
problems, but no one uses the same hardware either.

   At the outset, let me say that the machine is dual boot and the
problem does not occur in Windows.

MY SYSTEM - HDSP 9652, Gentoo-2.4.20-r7, Alsa 0.9.6 patched with
Thomas's HDSP patches from 8/27. ADAT1 out goes to an Alesis AI-3 D/A. 

PROBLEM STATEMENT- When playing mp3's using mpg123 I get a horrible,
loud and ugly high pitched static noise just before the audio starts to
play. It lasts about 1 second. I have also noticed that using hdspconf
to change the sample clock rate to 48K from 44.1K causes the same
horrible noise, but usually for a shorter period of time.

   One thing I've noticed by watching hdspconf is that when I start
playing the mp3 that hdspconf first says it loses sync, then goes to a
lock condition, and then goes back to a sync condition when the noise
stops. Also the sample frequency changes first to 32KHz and then back to
44.1K and then becomes synced again. This happens while the noise is
occurring.

   My speakers and headphones are driven from an AI-3 converter hooked
to to the ADAT1 port of the HDSP 9652. The AI-3 is ADAT, based but runs
at 48K unless it receives a input clock of a different frequency. The
9652 is set up to generate 44.1K as the master device, and the AI-3
seems to track it except when this noise occurs.

   One last thing. If I set my HDSP 9652 to 48KHz and attempt to play
and mp3, then the noise occurs, the frequency drops first to 32K And
then goes to 44.1K. The mp3 plays, but the card is left at 44.1K And
never goes back to 48K. Does this sound correct?

   I've tried all sorts of different clocking schemes but none of them
seem to solve this problem.

   I'm hoping that someone in the Alsa-Dev group will know something
about this and how I might fix it. If you want more technical data or
have some test you think I should try please let me know.

Thanks in advance,
Mark



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Re: HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Anders Torger]

I think this problem is related to what I mailed about a week ago (no 
reply). An HDSP master/slave sync problem in current CVS. Thus you are 
not alone with this type of problem.

On Tuesday 07 October 2003 00.55, Mark Knecht wrote:
> Hi,
>    I have a pretty frustrating problem with my Alsa setup. Right now
> I'm just looking for guidance about what's messed up and how I might
> get it fixed. I'm not sure if it's a driver issue, an Alsa issue, or
> a hardware issue. I have not yet found anyone else that has this
> exact set of problems, but no one uses the same hardware either.
>
>    At the outset, let me say that the machine is dual boot and the
> problem does not occur in Windows.
>
> MY SYSTEM - HDSP 9652, Gentoo-2.4.20-r7, Alsa 0.9.6 patched with
> Thomas's HDSP patches from 8/27. ADAT1 out goes to an Alesis AI-3
> D/A.
>
> PROBLEM STATEMENT- When playing mp3's using mpg123 I get a horrible,
> loud and ugly high pitched static noise just before the audio starts
> to play. It lasts about 1 second. I have also noticed that using
> hdspconf to change the sample clock rate to 48K from 44.1K causes the
> same horrible noise, but usually for a shorter period of time.
>
>    One thing I've noticed by watching hdspconf is that when I start
> playing the mp3 that hdspconf first says it loses sync, then goes to
> a lock condition, and then goes back to a sync condition when the
> noise stops. Also the sample frequency changes first to 32KHz and
> then back to 44.1K and then becomes synced again. This happens while
> the noise is occurring.
>
>    My speakers and headphones are driven from an AI-3 converter
> hooked to to the ADAT1 port of the HDSP 9652. The AI-3 is ADAT, based
> but runs at 48K unless it receives a input clock of a different
> frequency. The 9652 is set up to generate 44.1K as the master device,
> and the AI-3 seems to track it except when this noise occurs.
>
>    One last thing. If I set my HDSP 9652 to 48KHz and attempt to play
> and mp3, then the noise occurs, the frequency drops first to 32K And
> then goes to 44.1K. The mp3 plays, but the card is left at 44.1K And
> never goes back to 48K. Does this sound correct?
>
>    I've tried all sorts of different clocking schemes but none of
> them seem to solve this problem.
>
>    I'm hoping that someone in the Alsa-Dev group will know something
> about this and how I might fix it. If you want more technical data or
> have some test you think I should try please let me know.
>
> Thanks in advance,
> Mark
>
>
>
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> Alsa-devel@lists.sourceforge.net
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Re: HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Mark Knecht]

On Tue, 2003-10-07 at 00:23, Anders Torger wrote:
> I think this problem is related to what I mailed about a week ago (no 
> reply). An HDSP master/slave sync problem in current CVS. Thus you are 
> not alone with this type of problem.

Anders,
   Hi. I went back and looked at your post. Sorry I didn't have anything
to offer when you wrote it. Possibly the problems are related. I'm not
sure. I'm not on the latest CVS, so I wasn't at all sure that you were
speaking of anything other than the latest CVS.

   I agree that they may be related. Possibly my noise only happens
continuously when trying to sync to an external 48K source, and possibly
this is just a sign of it never syncing. When I set the Pref. Sync. Ref.
to ADAT1 and use AutoSync I get the noise continuously and the Sync
indicator just goes back and forth between lock and no lock. It never
gets to sync which I presume it should.

   So, Alsa developers, what's this about?

Thanks,
Mark




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Re: HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Paul Davis]

>   I agree that they may be related. Possibly my noise only happens
>continuously when trying to sync to an external 48K source, and possibly
>this is just a sign of it never syncing. When I set the Pref. Sync. Ref.
>to ADAT1 and use AutoSync I get the noise continuously and the Sync
>indicator just goes back and forth between lock and no lock. It never
>gets to sync which I presume it should.
>
>   So, Alsa developers, what's this about?

does the input to ADAT1 contain a valid clock signal? the symptoms you
have basically say that it doesn't. 


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Re: HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Mark Knecht]

On Tue, 2003-10-07 at 06:01, Paul Davis wrote:
> >   I agree that they may be related. Possibly my noise only happens
> >continuously when trying to sync to an external 48K source, and possibly
> >this is just a sign of it never syncing. When I set the Pref. Sync. Ref.
> >to ADAT1 and use AutoSync I get the noise continuously and the Sync
> >indicator just goes back and forth between lock and no lock. It never
> >gets to sync which I presume it should.
> >
> >   So, Alsa developers, what's this about?
> 
> does the input to ADAT1 contain a valid clock signal? the symptoms you
> have basically say that it doesn't. 

I agree. It does sound that way, but read the thread please. In my
machine's case I am dual boot and in my description I said this does not
happen under Windows.



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Re: HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Paul Davis]

>On Tue, 2003-10-07 at 06:01, Paul Davis wrote:
>> >   I agree that they may be related. Possibly my noise only happens
>> >continuously when trying to sync to an external 48K source, and possibly
>> >this is just a sign of it never syncing. When I set the Pref. Sync. Ref.
>> >to ADAT1 and use AutoSync I get the noise continuously and the Sync
>> >indicator just goes back and forth between lock and no lock. It never
>> >gets to sync which I presume it should.
>> >
>> >   So, Alsa developers, what's this about?
>> 
>> does the input to ADAT1 contain a valid clock signal? the symptoms you
>> have basically say that it doesn't. 
>
>I agree. It does sound that way, but read the thread please. In my
>machine's case I am dual boot and in my description I said this does not
>happen under Windows.

that would suggest that the driver is not setting the clock source
correctly. sync/lock/nolock is done by the h/w, and if the same config
works under windows, my guess it that the hardware has not been setup
under linux the way it is claimed to be.



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RE: HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Mark Knecht]

> >
> >I agree. It does sound that way, but read the thread please. In my
> >machine's case I am dual boot and in my description I said this does not
> >happen under Windows.
>
> that would suggest that the driver is not setting the clock source
> correctly. sync/lock/nolock is done by the h/w, and if the same config
> works under windows, my guess it that the hardware has not been setup
> under linux the way it is claimed to be.
>
Well, I agree, in the sense that we seem to be stating the obvious.

To the question at hand, how do we solve the problem and get the driver to
set the card up correctly?

Have I not set something up correctly? Is there something I can correct in
my Alsa setup that will fix this?

Or has the driver not correctly comprehended something about the HDSP 9652?

What is strange in my case is that the frequency is actually correct BEFORE
I start playing an mp3, for instance, and then when the mp3 starts playing
the frequency is set incorrectly for a short time, apparently causing the
noise, but it is eventually set back to the right frequency after a while.
In this case the frequency seems to get changed through other settings
before it comes to rest at the right frequency.

In the case of syncing to my 48K AI-3 source it never works, while it will
sync to other ADAT inputs, albeit they are typically at 44.1K.




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Re: HDSP 9652 sync problems cause loud noise in Alsa 0.9.6

[Takashi Iwai]

At Tue, 7 Oct 2003 08:26:47 -0700,
Mark Knecht wrote:
> 
> > >
> > >I agree. It does sound that way, but read the thread please. In my
> > >machine's case I am dual boot and in my description I said this does not
> > >happen under Windows.
> >
> > that would suggest that the driver is not setting the clock source
> > correctly. sync/lock/nolock is done by the h/w, and if the same config
> > works under windows, my guess it that the hardware has not been setup
> > under linux the way it is claimed to be.
> >
> Well, I agree, in the sense that we seem to be stating the obvious.
> 
> To the question at hand, how do we solve the problem and get the driver to
> set the card up correctly?
> 
> Have I not set something up correctly? Is there something I can correct in
> my Alsa setup that will fix this?
> 
> Or has the driver not correctly comprehended something about the HDSP 9652?
> 
> What is strange in my case is that the frequency is actually correct BEFORE
> I start playing an mp3, for instance, and then when the mp3 starts playing
> the frequency is set incorrectly for a short time, apparently causing the
> noise, but it is eventually set back to the right frequency after a while.
> In this case the frequency seems to get changed through other settings
> before it comes to rest at the right frequency.
> 
> In the case of syncing to my 48K AI-3 source it never works, while it will
> sync to other ADAT inputs, albeit they are typically at 44.1K.

it would be helpful if you show the contents of hdsp proc file before
and after playback (or at each action).  if Paul's guess is right, the
register values should be inconsistent.

now i'm looking at hdsp.c, and found that the system clock is changed
only when you do hw_params call explicitly, even if you set the sample
clock source as autosync.  (that's why it shows "master" as "system
clock mode" in Anders' last post.  if the current system rate and the
external rate are different, it shows as if "master".)

maybe we need to reset the system rate immediately when the sample
source is set to autosync.


well, i'm not an HDSP owner, so just a guess...


Takashi


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