Alsa-OSS - Pop at start of song update (rc2)

Alsa-OSS - Pop at start of song update (rc2)

[Mark Knecht]

Hi,
   This is a small update on the problem I've seen with loud pops and
crackles at the start of audio when using Alsa's OSS emulation. As
background, using xmms I am unable to play about 99% of the mp3, ogg and
wave files I have without getting a very loud noise when first starting
the playback. The noise also happens every time I pause and restart the
playback. It also happens with pretty much every audio or video viewed
and played by Mozilla. mplayer, xine, plugger-5.0 all have default
setups that cuase this on my system. 

   However, an interesting aspect was that this does not ever happen
when playing any of these files with an Alsa application instead. Using
that as a clue, I tried using alsaplayer through the oss layer instead
of directly into Alsa, using

alsaplayer -o oss

It turns out that this NEVER causes the noise. All mp3, ogg and wave
files play correctly using alsaplayer through the OSS layer.

   I'm not sure what this says, really. If alsaplayer can talk to the
OSS layer correctly, then you could say that every other app I've tried
is bad and all those apps need to be recoded. On the other hand, if so
many apps fail in my system, then is the problem with the OSS emulation
interface and that needs to be looked at?

   I also tried building the alsa-xmms plugin, but it fails with
Alsa-1.0.0rc2, so I'll file bug reports on that elsewhere.


Thanks,
Mark

Postscript: 

   Without support from a developer somewhere who is interested in
solving this I understand that this is not going to go much further than
this message. The problem has been there, and I have been reporting it
in one form or another for over 8 months. No one has stepped up to solve
it specifically, and not being a developer this is about as much as I
can do. I don't know what else I can do to muster some interest in
solving it. This is an RME product, which is one of the 'preferred'
hardware manufacturers for Linux audio. It's burning me today. It will
burn others later.

   Clearly I get that this problem occurs on very few systems, so I get
that it's not high priority. Maybe there's nothing that can get done
about it. That would be disappointing.

   From a practical point of view, this one problem pretty much causes
me to have to drop using Linux at all for browsing the web and is
forcing me back to Windows. I cannot handle super loud ugly noises at
the start of playing a simple 2-second wave file. A lot of what I do is
on the web, and every one plays badly on my system. Bummer...

   The only practical idea I can offer is that someone in the Alsa camp
should take up the task of developing a set of instructions for
configuring Mozilla. et. all, in such away as to make OSS not be used. I
think Alsa should support, but not depend on, OSS at all. Today it
depends on OSS by not providing clear info on how to use Alsa inside of
browsers.




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Re: Alsa-OSS - Pop at start of song update (rc2)

[Patrick Shirkey]

Mark Knecht wrote:
> Hi,
> 
>    The only practical idea I can offer is that someone in the Alsa camp
> should take up the task of developing a set of instructions for
> configuring Mozilla. et. all, in such away as to make OSS not be used. I
> think Alsa should support, but not depend on, OSS at all. Today it
> depends on OSS by not providing clear info on how to use Alsa inside of
> browsers.
> 

This is probably useful but the main problem I see is you are using a 
few apps that could be running alsa native but you are using the oss 
drivers instead.

mplayer will use whatever driver you specify in the config file. I 
assume xine is the same. Thats pretty much the best fix AFAICT. Then you 
only have to find a way to make sure you're java plugins don't make 
noise and stop using xmms until they fix the alsa driver.

Anything that xmms can stream mplayer can do too. Anything that doesn't 
require streaming alsaplayer can do.

Have you had major problems with java plugins? In this case you should 
look into ways to get around that. (Some people have been known to 
invest in a second $10 card just for browsing).





-- 
Patrick Shirkey - Boost Hardware Ltd.
Http://www.boosthardware.com
Http://www.djcj.org - The Linux Audio Users guide
========================================


  Apparently upon the beginning of the barrage, the donkey broke 
discipline and panicked, toppling the cart. At that point, the rockets 
disconnected from the timer, leaving them strewn around the street. 
Tethered to the now toppled cart, the donkey was unable to escape before 
the arrival of U.S. troops.

United Press International
Rockets on donkeys hit major Baghdad sites

By P. MITCHELL PROTHERO
Published 11/21/2003 11:13 AM



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Re: Alsa-OSS - Pop at start of song update (rc2)

[Mark Knecht]

On Sun, 2003-12-07 at 10:28, Patrick Shirkey wrote:
> (Some people have been known to 
> invest in a second $10 card just for browsing).

Sure. I've got an on-board sound chip of some type. I used to have it
enabled. Sounds like I probably need to do something like that and patch
it with a cable back into the RME which would get the audio sent to
speakers and headphones. I think this problem is unlikely to ever get
addressed seriously.

However, as I remember it, there were conflicts having both the on-board
chip and the RME both on at the same time. MIDI stuff or something like
that.

Cheers,
Mark



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Re: Alsa-OSS - Pop at start of song update (rc2)

[Ross Vandegrift]

On Sun, Dec 07, 2003 at 10:03:15AM -0800, Mark Knecht wrote:
>    This is a small update on the problem I've seen with loud pops and
> crackles at the start of audio when using Alsa's OSS emulation. As
> background, using xmms I am unable to play about 99% of the mp3, ogg and
> wave files I have without getting a very loud noise when first starting
> the playback. The noise also happens every time I pause and restart the
> playback. It also happens with pretty much every audio or video viewed
> and played by Mozilla. mplayer, xine, plugger-5.0 all have default
> setups that cuase this on my system. 

Hi Mark,

	Are you by chance using a sound server of some kind that keeps
the device open and mapped?  For example, esd keep the device open and
when it's not in use, it's writing zeroes to the sound device.

	If there was a bug in esd and it wasn't actually writing
zeroes, but some other constant value, things would be silent while
nothing is playing.  When actual sound starts, this could have an actual
zero at the beginning, causing a pop!

	Of course, you say you're using oss, so probably no esd is
involved.  Maybe dmix is being used and doing something like this?

>    However, an interesting aspect was that this does not ever happen
> when playing any of these files with an Alsa application instead. Using
> that as a clue, I tried using alsaplayer through the oss layer instead
> of directly into Alsa, using
> 
> alsaplayer -o oss

This difference is kind of telling - if it were a problem in the ALSA
OSS emulation layer, this should almost certainly exhibit the problem.
Of course, it could be a subtle API compatibility issue, but that seems
unlikely to me - people should see it on other hardware and it should be
common.

If you're using something like dmix, I'd try cutting it out of the
picture.

-- 
Ross Vandegrift
ross@willow.seitz.com

A Pope has a Water Cannon.                               It is a Water Cannon.
He fires Holy-Water from it.                        It is a Holy-Water Cannon.
He Blesses it.                                 It is a Holy Holy-Water Cannon.
He Blesses the Hell out of it.          It is a Wholly Holy Holy-Water Cannon.
He has it pierced.                It is a Holey Wholly Holy Holy-Water Cannon.
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rc2 - snd-via82xx - really sounds bad - distorted, resampled, phasey

[Mark Knecht]

On Sun, 2003-12-07 at 10:28, Patrick Shirkey wrote:
> (Some people have been known to 
> invest in a second $10 card just for browsing).
> 

Patrick, 
   Hi. Ok, since you suggested it I set up this Via 8235 sound chip on
my system as the primary sound chip. However, it's sounding amazingly
bad! It's terribly distorted and even at the best of times sounds very,
very,phasey. I can pretty much hear what sound like terrible resampling
noise, maybe like it's going from 44.1K up to 48K or something.

Any idea why? I hope it's just a configuration mistake.

I've tried both alsaplayer and xmms playing a few mp3's and the results
are always the same going through the 8235.

The 8235 output is cabled to an input on the AI-3 A/D, inputs 3/4. I've
also got Pro Tools coming in on inputs 1/2. Audio from Pro Tools is
fine, while audio from the 8235 is dirty, resampled and phasey. The AI-3
does not show any clipping on the signal coming from the 8235, so I
don't think it's really a levels issue.

Is the 8235 a 44.1K only type device? I don't think so since I see 44.1K
number in /proc/asound/card0/

I haven't figured out how to run alsaplayer directly though Alsa when
the HDSP is the second card, but using Jack I can run alsaplayer and the
sound is much better.

I think there have been similar comments since rc1 about this sort of
thing on the Intel sound chips possibly? Are others using rc2
successfully with this chip or could this be a similar problem?

The sound is so bad as to be unlistenable. 

Current .asoundrc and modules.conf below...

Thanks,
Mark

pcm.via82xx {
           type hw
           card 0
         }

ctl.via82xx {
           type hw
           card 0
         }

pcm.hdsp {
           type hw
           card 1
         }

ctl.hdsp {
           type hw
           card 1
         }

pcm_slave.hdsp {
          pcm "hw:0"
          channels 26
        }

pcm.playback_5_6 {
          type dshare
          slave hdsp
          ipc_key 314159265    # some unique number
          ipc_key_add_uid yes   # "no" to let multiple users share it
          bindings {
                0 5
                1 6
          }
        }

pcm.dsp {
          type plug
          slave.pcm playback_5_6
        }


# ALSA portion
alias char-major-116 snd
# OSS/Free portion
alias char-major-14 soundcore

##
## IMPORTANT:
## You need to customise this section for your specific sound card(s)
## and then run `update-modules' command.
## Read alsa-driver's INSTALL file in /usr/share/doc for more info.
##

##  ALSA portion
alias snd-card-0 snd-via82xx
alias snd-card-1 snd-hdsp
alias snd-card-2 snd-usb-audio


##  OSS/Free portion
alias sound-slot-0 snd-card-0
alias sound-slot-1 snd-card-1
alias sound-slot-2 snd-card-2
##

# OSS/Free portion - card #0 (Via8233)
alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-8 snd-seq-oss
alias sound-service-0-12 snd-pcm-oss

# OSS/Free portion - card #1 (HDSP9652)
alias sound-service-1-0 snd-mixer-oss
alias sound-service-1-1 snd-seq-oss
alias sound-service-1-3 snd-pcm-oss
alias sound-service-1-8 snd-seq-oss
alias sound-service-1-12 snd-pcm-oss

alias /dev/mixer snd-mixer-oss
alias /dev/dsp snd-pcm-oss
alias /dev/midi snd-seq-oss

# Set this to the correct number of cards.
options snd cards_limit=3
add options -k snd-card-0
add options -k snd-card-1
add options -k snd-card-2

### modules-update: end processing /etc/modules.d/alsa




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Re: rc2 - snd-via82xx - really sounds bad - distorted, resampled, phasey

[Tim Goetze]

Mark Knecht wrote:

>   Hi. Ok, since you suggested it I set up this Via 8235 sound chip on
>my system as the primary sound chip. However, it's sounding amazingly
>bad! It's terribly distorted and even at the best of times sounds very,
>very,phasey. I can pretty much hear what sound like terrible resampling
>noise, maybe like it's going from 44.1K up to 48K or something.

have you played around with the via82xx 'dxs_support' module parameter
yet? your modules.conf suggests you haven't. the driver didn't guess
the value right on this box fwiw, i had to set it manually.

add 'options snd-via82xx dxs_support=X' to modules.conf where 0 < X <= 4.
there's some comments at the head of alsa-kernel/pci/via82xx.c that
shed some more light on the issue.

hth,

tim


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Re: rc2 - snd-via82xx - really sounds bad - distorted, resampled, phasey

[drclaw]

Hi, I have that exact same problem with a via8235 chip, and the only way
I have found to fix it was to change 48000 to 44100 on Line 83 in
alsa-kernel/pci/via82xx.c:
static int ac97_clock[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 48000};
I actuially wrote a mail earlier today on the same subject (called
viasomehting8235 clock problems or something).  It seems to work fine
after I make this change, btw.  

784 - Michael C. Piantedosi - drclaw@dogsolitude.org


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Re: rc2 - snd-via82xx - really sounds bad - distorted, resampled, phasey

[Mark Knecht]

On Sun, 2003-12-07 at 20:53, drclaw@dogsolitude.org wrote:
> Hi, I have that exact same problem with a via8235 chip, and the only way
> I have found to fix it was to change 48000 to 44100 on Line 83 in
> alsa-kernel/pci/via82xx.c:
> static int ac97_clock[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 48000};
> I actuially wrote a mail earlier today on the same subject (called
> viasomehting8235 clock problems or something).  It seems to work fine
> after I make this change, btw.  
> 
> 784 - Michael C. Piantedosi - drclaw@dogsolitude.org

Interesting info. Thanks.

- Mark



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