[ALSA - driver 0001928]: Only Problems with Surround Sound

[bugtrack@alsa-project.org]

A NOTE has been added to this issue.
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<https://bugtrack.alsa-project.org/alsa-bug/view.php?id=1928> 
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Reported By:                the-me
Assigned To:                tiwai
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Project:                    ALSA - driver
Issue ID:                   1928
Category:                   PCI - cmipci
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     assigned
Distribution:               Debian Sid
Kernel Version:             2.6.15.6
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Date Submitted:             03-15-2006 22:02 CET
Last Modified:              03-15-2006 22:55 CET
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Summary:                    Only Problems with Surround Sound
Description: 
Hi.
I've got a big problem ( like many other users of many other soundcards ).
My Surroundsound didn't work!
I've got the Terratec Aureon 5.1 Fun soundcard. At alsamixer, I haven't
got any LFE or Center Options ( why? there stands in the topic *MC6 ( for
6 channels! ) ).
Now I tried it with a .asoundrc. Result:
Now my Rear / Front / Center worked correctly at listening to mp3s, the
subwoofer ( lfe ) gives also high sound out, not only deep!!! thats a big
problem.

I tried it with the following .asoundrc =>
http://www.linux-development.org/nopaste/?800

now I found an entry at an wiki of alsa.opensrc.org , which contains
following:

---------------
Custom Routing of Signals to Surround Outputs

With a little .asoundrc hackery, you can easily route signals around any
way you like. See for example FAQ028 for an example of how to play a
stereo signal over booth front and rear speakers simultaneously. The
example can easily be adapted to suit your needs. FAQ028 tells us how to
route our "normal" stereo signals to 4 or 5 speakers. It would be nice to
process the signal for the subwoofer with a lowpass filter. Thats's where
the LADSPA plugins come in handy:

pcm.lowpass {
type ladspa
slave.pcm ...
path "/usr/lib/ladspa"
plugins [ {
label lpf
input {
controls [ 50 ]
}
} ]
}

This filter will cut off everything above 50 Hz. Only problem: How do I
send only one channel (a mixture of right and left channel) through this
filter? And where do I send the filtered signal? I have tried this setup:

# move channel 0 to channel 2
pcm.move0to2 {
type route
slave.pcm 3to6
slave.channels 3
ttable.0.2 1
}
# 3to6 has 3 input and 6 output channels
# the stereo signal is on ch. 0 and 1
# ch.0 is copied to 0 and 2 (front and rear)
# ch.1 is copied to 1 and 3 (front and rear)
# ch.0 and ch.1 will is mixed to ch.4 (center)
# ch.2 is routed to ch.5 (subwoofer)
pcm.3to6 {
type route
slave.pcm "surround51"
slave.channels 6
ttable.0.0 1
ttable.1.1 1
ttable.0.2 1
ttable.1.3 1
ttable.0.4 0.5
ttable.1.4 0.5
ttable.2.5 1
}

This seems to work from the lowpass filter to the output (I have tried
aplay -D plug:lowpass sound.wav). But still the question - How to I get
the data of one channel to the lowpass filter?
---------------

my question, how can I set up this lowpassfilter only for my LFE channel??
I need it!

mfg Patrick
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----------------------------------------------------------------------
 rlrevell - 03-15-06 22:24 
----------------------------------------------------------------------
Your surround sound (playback of 5.1 audio) is working perfectly - what you
want is upmixing of stereo sounds to 5.1.

This is not really appropriate for a bug report as it's not a bug.  Please
post your question to the alsa-user list.

----------------------------------------------------------------------
 the-me - 03-15-06 22:55 
----------------------------------------------------------------------
hmm, you can see this like a feature request.
an alsa option to enable this in alsamixer will be good.

but do you have any idea?

Issue History
Date Modified  Username       Field                    Change              
======================================================================
03-15-06 22:02 the-me         New Issue                                    
03-15-06 22:02 the-me         Distribution              => Debian Sid      
03-15-06 22:02 the-me         Kernel Version            => 2.6.15.6        
03-15-06 22:24 rlrevell       Note Added: 0008575                          
03-15-06 22:55 the-me         Note Added: 0008576                          
======================================================================




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