alsa-lib/src/alsa.conf

pcm.default {
	type plug
	slave.pcm {
		type hw
		card 0
		device 0
	}
}

pcm.hw {
	$.0 CARD
	$.1 DEV
	$.2 SUBDEV
	$.CARD {
		type integer
	}
	$.DEV {
		type integer
	}
	$.SUBDEV {
		type integer
		default -1
	}		
	type hw
	card $CARD
	device $DEV
	subdevice $SUBDEV
}

pcm.plughw {
	$.0 CARD
	$.1 DEV
	$.2 SUBDEV
	$.CARD {
		type integer
	}
	$.DEV {
		type integer
	}
	$.SUBDEV {
		type integer
		default -1
	}		
	type plug
	slave.pcm {
		type hw
		card $CARD
		device $DEV
		subdevice $SUBDEV
	}
}

pcm.plug {
	$.0 SLAVE
	$.SLAVE {
		type string
	}
	type plug
	slave.pcm $SLAVE
}

pcm.shm {
	$.0 SOCKET
	$.1 PCM
	$.SOCKET {
		type string
	}
	$.PCM {
		type string
	}
	type shm
	server $SOCKET
	pcm $PCM
}

pcm.tee {
	$.0 SLAVE
	$.1 FILE
	$.2 FORMAT
	$.SLAVE {
		type string
	}
	$.FILE {
		type string
	}
	$.FORMAT {
		type string
		default raw
	}
	type file
	slave.pcm $SLAVE
	file $FILE
	format $FORMAT
}

pcm.file {
	$.0 FILE
	$.1 FORMAT
	$.FILE {
		type string
	}
	$.FORMAT {
		type string
		default raw
	}
	type file
	slave.pcm null
	file $FILE
	format $FORMAT
}

pcm.surround40 {
	$.0 CARD
	$.1 DEV
	$.CARD {
		type integer
	}
	$.DEV {
		type integer
		default 0
	}
	type surround
	card $CARD
	device $DEVICE
	stype 4.0
}
	
pcm.surround51 {
	$.0 CARD
	$.1 DEV
	$.CARD {
		type integer
	}
	$.DEV {
		type integer
		default 0
	}
	type surround
	card $CARD
	device $DEVICE
	stype 5.1
}
	
pcm.null {
	type null
}
	
ctl.default {
	type hw
	card 0
}

ctl.hw {
	$.0 CARD
	$.CARD {
		type integer
	}
	type hw
	card $CARD
}

ctl.shm {
	$.0 SOCKET
	$.1 PCM
	$.SOCKET {
		type string
	}
	$.PCM {
		type string
	}
	type shm
	server $SOCKET
	ctl $PCM
}

rawmidi.hw {
	$.0 CARD
	$.1 DEV
	$.2 SUBDEV
	$.CARD {
		type integer
	}
	$.DEV {
		type integer
	}
	$.SUBDEV {
		type integer
		default -1
	}		
	type hw
	card $CARD
	device $DEV
	subdevice $SUBDEV
}

seq.hw {
	type hw
}

pcm.iec958 {
	$.0 PCM
        $.1 AES0
        $.2 AES1
        $.3 AES2
        $.4 AES3
	$.PCM {
		type string
		default default
	}
	$.AES0 {
		type integer
		# IEC958_AES0_PROFESSIONAL | IEC958_AES0_NONAUDIO |
		# IEC958_AES0_PRO_EMPHASIS_NONE | IEC958_AES0_PRO_FS_48000
		default 0x87
	}
	$.AES1 {
		type integer
		default 0x00
	}
	$.AES2 {
		type integer
		default 0x00
	}
	$.AES3 {
		type integer
		default 0x00
	}
	type hooks
	slave.pcm $PCM
	hooks.0 {
		type ctl_elems
		args.0 {
			name "IEC958 Playback PCM Stream"
			subdevice 0
			preserve true
			lock true
			value.0 $AES0
			value.1 $AES1
			value.2 $AES2
			value.3 $AES3
		}
	}
}