[mythtv-users] alsa rate change on via8237 spdif

Robin Gilks g8ecj at gilks.org
Fri Jun 22 07:54:22 UTC 2007

> If the above description doesn't work, use the ALSA configuration from
> the wiki and set digital-hw to:
> pcm.digital-hw {
>   type hw
>   card 0
>   # The default value for device is 0, so no need to specify
>   device 0
>   subdevice 3
> }
> and IEC958 unmuted, IEC958 Playback AC97-SPSA on 100 ("full" volume in
> alsamixer), IEC958 Playback Source on IEC958 In.  Then set up Myth to
> use ALSA:digital or ALSA:mixed-digital.
> amixer sset 'IEC958' unmute
> amixer sset 'IEC958 Output' unmute
> amixer sset 'IEC958 Playback AC97-SPSA' 3
> amixer sset 'IEC958 Playback Source' 'IEC958 In'
> At least one of the two configurations will work.  I.e. device should be
> 0 and subdevice should be either 0 (default) or 3 in digital-hw.  You
> should use the configuration file from the wiki, where the only
> modification is to the device (and possibly adding a subdevice) for
> digital-hw.  Then specify either ALSA:digital or ALSA:mixed-digital as
> your "Audio output device" in Myth.
> The IEC958 settings will differ depending on which approach you use, so
> ensure they're as specified.
> If both approaches work, use the second as it may allow you to do nice
> things like 32kHz or 44.1kHz AC-3 passthrough (but doing so would
> require additional plumbing), which you probably couldn't do with the
> first.
> Mike

Major problem Mike...
media ~ # amixer sset 'IEC958 Playback Source' 'PCM'
amixer: Unable to find simple control 'IEC958 Playback Source',0

This is the full result:

media ~ # amixer sset 'IEC958' unmute
Simple mixer control 'IEC958',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
media ~ # amixer sset 'IEC958 Output' unmute
Simple mixer control 'IEC958 Output',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
media ~ # amixer sset 'IEC958 Playback AC97-SPSA' 0
Simple mixer control 'IEC958 Playback AC97-SPSA',0
  Capabilities: volume volume-joined
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 3
  Mono: 0 [0%]
media ~ # amixer sset 'IEC958 Playback Source' 'PCM'
amixer: Unable to find simple control 'IEC958 Playback Source',0

I've checked the options I have compiled into alsamixer in case its
something obvious like no AC3 support (I'm using Gentoo) but no luck

BTW - my nvidia system also complains in the same fashion:
zeus # amixer sset 'IEC958 Playback Source' 'PCM'
amixer: Unable to find simple control 'IEC958 Playback Source',0

The list of controls I have on the 8237 is as follows (using a Via1617A
codec according to alsamixer):

media ~ # amixer controls
numid=11,iface=MIXER,name='Master Mono Playback Switch'
numid=12,iface=MIXER,name='Master Mono Playback Volume'
numid=1,iface=MIXER,name='Master Playback Switch'
numid=2,iface=MIXER,name='Master Playback Volume'
numid=9,iface=MIXER,name='Headphone Playback Switch'
numid=10,iface=MIXER,name='Headphone Playback Volume'
numid=34,iface=MIXER,name='3D Control - Center'
numid=35,iface=MIXER,name='3D Control - Depth'
numid=31,iface=MIXER,name='3D Control - Switch'
numid=26,iface=MIXER,name='PCM Playback Switch'
numid=27,iface=MIXER,name='PCM Playback Volume'
numid=7,iface=MIXER,name='Surround Playback Switch'
numid=8,iface=MIXER,name='Surround Playback Volume'
numid=3,iface=MIXER,name='Center Playback Switch'
numid=4,iface=MIXER,name='Center Playback Volume'
numid=5,iface=MIXER,name='LFE Playback Switch'
numid=6,iface=MIXER,name='LFE Playback Volume'
numid=20,iface=MIXER,name='Line Playback Switch'
numid=21,iface=MIXER,name='Line Playback Volume'
numid=22,iface=MIXER,name='CD Playback Switch'
numid=23,iface=MIXER,name='CD Playback Volume'
numid=19,iface=MIXER,name='Mic Boost (+20dB)'
numid=33,iface=MIXER,name='Mic Select'
numid=17,iface=MIXER,name='Mic Playback Switch'
numid=18,iface=MIXER,name='Mic Playback Volume'
numid=15,iface=MIXER,name='Phone Playback Switch'
numid=16,iface=MIXER,name='Phone Playback Volume'
numid=13,iface=MIXER,name='PC Speaker Playback Switch'
numid=14,iface=MIXER,name='PC Speaker Playback Volume'
numid=24,iface=MIXER,name='Aux Playback Switch'
numid=25,iface=MIXER,name='Aux Playback Volume'
numid=32,iface=MIXER,name='Mono Output Select'
numid=28,iface=MIXER,name='Capture Source'
numid=29,iface=MIXER,name='Capture Switch'
numid=30,iface=MIXER,name='Capture Volume'
numid=36,iface=MIXER,name='IEC958 Playback Con Mask'
numid=37,iface=MIXER,name='IEC958 Playback Pro Mask'
numid=40,iface=MIXER,name='IEC958 Playback AC97-SPSA'
numid=38,iface=MIXER,name='IEC958 Playback Default'
numid=39,iface=MIXER,name='IEC958 Playback Switch'
numid=44,iface=MIXER,name='IEC958 Output Switch'
numid=41,iface=MIXER,name='External Amplifier'
numid=42,iface=MIXER,name='Input Source Select'
numid=43,iface=MIXER,name='Input Source Select',index=1
numid=45,iface=MIXER,name='VIA DXS Playback Volume'
numid=46,iface=MIXER,name='VIA DXS Playback Volume',index=1
numid=47,iface=MIXER,name='VIA DXS Playback Volume',index=2
numid=48,iface=MIXER,name='VIA DXS Playback Volume',index=3

I tried using amixer get on all of the IEC958 controls but is complains
about some of them:

media ~ # amixer get 'IEC958 Playback Default'
amixer: Unable to find simple control 'IEC958 Playback Default',0

media ~ # amixer get 'IEC958 Playback Switch'
amixer: Unable to find simple control 'IEC958 Playback Switch',0

At this point I'm a bit boggled!

Robin Gilks

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