[ALSA - driver 0001658]: Capture happens only on one channel

[bugtrack@alsa-project.org]

A NOTE has been added to this issue.
======================================================================
<https://bugtrack.alsa-project.org/alsa-bug/view.php?id=1658> 
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Reported By:                phil_troin
Assigned To:                
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Project:                    ALSA - driver
Issue ID:                   1658
Category:                   PCI - intel8x0
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     new
Distribution:               Gentoo
Kernel Version:             2.6.14-gentoo-r2
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Date Submitted:             12-18-2005 08:40 CET
Last Modified:              01-13-2006 17:51 CET
======================================================================
Summary:                    Capture happens only on one channel
Description: 
When I am playing a CD, if I capture the sound output via the capture
channel OR the CD channel (amixer output attached), the captured sound is
only one one channel (the right one) and is very distorted.
The audio plays normally in stereo on the speakers.
======================================================================

----------------------------------------------------------------------
 vsu - 01-13-06 17:46 
----------------------------------------------------------------------
Here I see what looks like the same problem with snd-via82xx and Realtek
ALC200 (not really tested with input signals, but values of ac97 mixer
registers are wrong). Kernel 2.6.14, alsa-driver, alsa-lib and alsa-utils
1.0.10.

Initially the capture source is set to Mic:

$ cat /proc/asound/card0/codec97#0/ac97#0-0+regs | grep 0:1a 
0:1a = 0000
$ amixer cget iface=MIXER,name='Capture Source'               
numid=24,iface=MIXER,name='Capture Source'
  ; type=ENUMERATED,access=rw---,values=2,items=8
  ; Item #0 'Mic'
  ; Item #1 'CD'
  ; Item #2 'Video'
  ; Item #3 'Aux'
  ; Item #4 'Line'
  ; Item #5 'Mix'
  ; Item #6 'Mix Mono'
  ; Item #7 'Phone'
  : values=0,0

Then I run alsamixer, press F4 to switch to capture view, move to "Line"
and press Space - alsamixer shows that Line is now selected for capture.

However, the contents of the ac97 register 0x1a is wrong:

$ cat /proc/asound/card0/codec97#0/ac97#0-0+regs | grep 0:1a
0:1a = 0400

Only the left channel was switched to Line - the right channel remains set
to Mic.  And amixer shows this too:

$ amixer cget iface=MIXER,name='Capture Source'
numid=24,iface=MIXER,name='Capture Source'
  ; type=ENUMERATED,access=rw---,values=2,items=8
  ; Item #0 'Mic'
  ; Item #1 'CD'
  ; Item #2 'Video'
  ; Item #3 'Aux'
  ; Item #4 'Line'
  ; Item #5 'Mix'
  ; Item #6 'Mix Mono'
  ; Item #7 'Phone'
  : values=4,0

But the simple mixer values do not agree with this:

$ amixer sget 'Line'
Simple mixer control 'Line',0
  Capabilities: pvolume pswitch pswitch-joined cswitch cswitch-joined
cswitch-exclusive
  Capture exclusive group: 0
  Playback channels: Front Left - Front Right
  Capture channels: Front Left - Front Right
  Limits: Playback 0 - 31
  Front Left: Playback 0 [0%] [off] Capture [on]
  Front Right: Playback 0 [0%] [off] Capture [on]
$ amixer sget 'Mic'                                         
Simple mixer control 'Mic',0
  Capabilities: pvolume pvolume-joined pswitch pswitch-joined cswitch
cswitch-joined cswitch-exclusive
  Capture exclusive group: 0
  Playback channels: Mono
  Capture channels: Front Left - Front Right
  Limits: Playback 0 - 31
  Mono: Playback 0 [0%] [off]
  Front Left: Capture [off]
  Front Right: Capture [off]

If I use "amixer cset", I can set the mixer properly:

$ amixer cset iface=MIXER,name='Capture Source' 4,4
numid=24,iface=MIXER,name='Capture Source'
  ; type=ENUMERATED,access=rw---,values=2,items=8
  ; Item #0 'Mic'
  ; Item #1 'CD'
  ; Item #2 'Video'
  ; Item #3 'Aux'
  ; Item #4 'Line'
  ; Item #5 'Mix'
  ; Item #6 'Mix Mono'
  ; Item #7 'Phone'
  : values=4,4
$ cat /proc/asound/card0/codec97#0/ac97#0-0+regs | grep 0:1a
0:1a = 0404

So it looks like the kernel driver and low-level mixer access in alsa-lib
works correctly, but the simple mixer layer in alsa-lib is broken.

----------------------------------------------------------------------
 tiwai - 01-13-06 17:51 
----------------------------------------------------------------------
This should have been already fixed in the latest version.

Issue History
Date Modified  Username       Field                    Change              
======================================================================
12-18-05 08:40 phil_troin     New Issue                                    
12-18-05 08:40 phil_troin     File Added: amixout                          
12-18-05 08:40 phil_troin     Distribution              => Gentoo          
12-18-05 08:40 phil_troin     Kernel Version            => 2.6.14-gentoo-r2
12-18-05 12:00 linuxbear      Note Added: 0007071                          
12-18-05 12:02 linuxbear      Note Edited: 0007071                         
12-27-05 10:34 linuxbear      Issue Monitored: linuxbear                    
01-07-06 06:24 tgutwin        Note Added: 0007508                          
01-07-06 06:25 tgutwin        Issue Monitored: tgutwin                     
01-09-06 01:34 legluondunet   Note Added: 0007529                          
01-09-06 01:35 legluondunet   File Added: alsa.conf.record1channel              
     
01-09-06 01:37 legluondunet   File Added: alsa.conf.ubuntu                    
01-09-06 01:43 legluondunet   Note Added: 0007530                          
01-13-06 02:17 rlrevell       Note Added: 0007615                          
01-13-06 14:29 Matthias KoenigNote Added: 0007640                          
01-13-06 17:12 legluondunet   Note Added: 0007644                          
01-13-06 17:46 vsu            Note Added: 0007645                          
01-13-06 17:49 vsu            Issue Monitored: vsu                         
01-13-06 17:51 tiwai          Note Added: 0007646                          
======================================================================




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