Enabling nForce4 optical SPDIF output

From MythTV

1 Background
2 /etc/asound.state File
3 MythTV Setup

Background

Many users with Nvidia4 based motherboards have problems enabling the optical audio output from their motherboard in Linux. The default values set by the alsa driver do not enable the optical output, and it is not possible to enable it using the alsamixer.

A solution was found by changing the /etc/asound.state file directly.

Short howto:

save the asound.state file below as "/etc/asound.state"
Enter the command "alsactl restore"

Due to differences in the alsa driver and the support circuits you might experience error messages of the following kind:

alsactl: set_control:894: warning: name mismatch (Mic Boost (+20dB)/Mic Boost (+20dB) Capture Switch) for control #17

alsactl: set_control:896: warning: index mismatch (0/0) for control #17

alsactl: set_control:898: failed to obtain info for control #17 (Operation not permitted)

This means that on your hardware, the name of control #17 is not "Mic Boost (+20dB)" but instead "Mic Boost (+20dB) Capture Switch".

To fix this problem, edit the /etc/asound.state file and change the name of control to the correct name.

3. Fix any problems in the asound.state file as described above.

4. Test your setup by playing an audio file while using the optical output. The optical output should now be able to output regular stereo and surround depending on your audio source.

[edit]

/etc/asound.state File

Save the following file as /etc/asound.state

/etc/asound.state

state.CK804 {
	control.1 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Master Playback Switch'
		value true
	}
	control.2 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 31'
		iface MIXER
		name 'Master Playback Volume'
		value.0 22
		value.1 22
	}
	control.3 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Center Playback Switch'
		value false
	}
	control.4 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 1
		comment.range '0 - 31'
		iface MIXER
		name 'Center Playback Volume'
		value 31
	}
	control.5 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'LFE Playback Switch'
		value true
	}
	control.6 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 1
		comment.range '0 - 31'
		iface MIXER
		name 'LFE Playback Volume'
		value 13
	}
	control.7 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 2
		iface MIXER
		name 'Surround Playback Switch'
		value.0 false
		value.1 false
	}
	control.8 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 31'
		iface MIXER
		name 'Surround Playback Volume'
		value.0 0
		value.1 0
	}
	control.9 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Master Mono Playback Switch'
		value false
	}
	control.10 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 1
		comment.range '0 - 31'
		iface MIXER
		name 'Master Mono Playback Volume'
		value 0
	}
	control.11 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'PC Speaker Playback Switch'
		value false
	}
	control.12 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 1
		comment.range '0 - 15'
		iface MIXER
		name 'PC Speaker Playback Volume'
		value 0
	}
	control.13 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Phone Playback Switch'
		value false
	}
	control.14 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 1
		comment.range '0 - 31'
		iface MIXER
		name 'Phone Playback Volume'
		value 0
	}
	control.15 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Mic Playback Switch'
		value false
	}
	control.16 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 1
		comment.range '0 - 31'
		iface MIXER
		name 'Mic Playback Volume'
		value 0
	}
	control.17 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Mic Boost (+20dB) Capture Switch'
		value false
	}
	control.18 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Line Playback Switch'
		value false
	}
	control.19 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 31'
		iface MIXER
		name 'Line Playback Volume'
		value.0 0
		value.1 0
	}
	control.20 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'CD Playback Switch'
		value false
	}
	control.21 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 31'
		iface MIXER
		name 'CD Playback Volume'
		value.0 0
		value.1 0
	}
	control.22 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Aux Playback Switch'
		value false
	}
	control.23 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 31'
		iface MIXER
		name 'Aux Playback Volume'
		value.0 0
		value.1 0
	}
	control.24 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'PCM Playback Switch'
		value true
	}
	control.25 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 31'
		iface MIXER
		name 'PCM Playback Volume'
		value.0 22
		value.1 22
	}
	control.26 {
		comment.access 'read write'
		comment.type ENUMERATED
		comment.count 2
		comment.item.0 Mic
		comment.item.1 CD
		comment.item.2 Video
		comment.item.3 Aux
		comment.item.4 Line
		comment.item.5 Mix
		comment.item.6 'Mix Mono'
		comment.item.7 Phone
		iface MIXER
		name 'Capture Source'
		value.0 Mic
		value.1 Mic
	}
	control.27 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Capture Switch'
		value true
	}
	control.28 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 15'
		iface MIXER
		name 'Capture Volume'
		value.0 0
		value.1 0
	}
	control.29 {
		comment.access 'read write'
		comment.type ENUMERATED
		comment.count 1
		comment.item.0 Mix
		comment.item.1 Mic
		iface MIXER
		name 'Mono Output Select'
		value Mix
	}
	control.30 {
		comment.access 'read write'
		comment.type ENUMERATED
		comment.count 1
		comment.item.0 Mic1
		comment.item.1 Mic2
		iface MIXER
		name 'Mic Select Capture Switch'
		value Mic1
	}
	control.31 {
		comment.access read
		comment.type IEC958
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Con Mask'
		value '0fff000f00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'
	}
	control.32 {
		comment.access read
		comment.type IEC958
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Pro Mask'
		value cf00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
	}
	control.33 {
		comment.access 'read write'
		comment.type IEC958
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Default'
		value '0082000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'
	}
	control.34 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Switch'
		value true
	}
	control.35 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 1
		comment.range '0 - 3'
		iface MIXER
		name 'IEC958 Playback AC97-SPSA'
		value 0
	}
	control.36 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Duplicate Front'
		value false
	}
	control.37 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Mic Front Input Switch'
		value false
	}
	control.38 {
		comment.access 'read write'
		comment.type ENUMERATED
		comment.count 1
		comment.item.0 Shared
		comment.item.1 Independent
		iface MIXER
		name 'Surround Jack Mode'
		value Shared
	}
	control.39 {
		comment.access 'read write'
		comment.type ENUMERATED
		comment.count 1
		comment.item.0 '2ch'
		comment.item.1 '4ch'
		comment.item.2 '6ch'
		iface MIXER
		name 'Channel Mode'
		value '2ch'
	}
	control.40 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'IEC958 Capture Switch'
		value false
	}
	control.41 {
		comment.access 'read write'
		comment.type ENUMERATED
		comment.count 1
		comment.item.0 PCM
		comment.item.1 'Analog In'
		comment.item.2 'IEC958 In'
		iface MIXER
		name 'IEC958 Playback Source'
		value PCM
	}
	control.42 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'External Amplifier'
		value true
	}
}

[edit]