[alsa-devel] explicit commandline control of speakers vs headphone output
eric_holstege at yahoo.com
Thu Aug 26 20:40:49 CEST 2010
My specific sound HW is "nVidia Corporation MCP79 High Definition Audio
00:08.0 Audio device: nVidia Corporation MCP79 High Definition Audio
Subsystem: Micro-Star International Co., Ltd. Device 4570
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 23
Memory at fae78000 (32-bit, non-prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: HDA Intel
Kernel modules: snd-hda-intel
udi = '/org/freedesktop/Hal/devices/pci_10de_ac0'
info.linux.driver = '*HDA Intel*' (string)
info.parent = '/org/freedesktop/Hal/devices/computer' (string)
info.product = 'MCP79 High Definition Audio' (string)
info.subsystem = 'pci' (string)
info.udi = '/org/freedesktop/Hal/devices/pci_10de_ac0' (string)
info.vendor = 'nVidia Corporation' (string)
linux.hotplug_type = 2 (0x2) (int)
linux.subsystem = 'pci' (string)
linux.sysfs_path = '/sys/devices/pci0000:00/0000:00:08.0' (string)
pci.device_class = 4 (0x4) (int)
pci.device_protocol = 0 (0x0) (int)
pci.device_subclass = 3 (0x3) (int)
pci.linux.sysfs_path = '/sys/devices/pci0000:00/0000:00:08.0' (string)
pci.product = '*MCP79 High Definition Audio*' (string)
pci.product_id = 2752 (*0xac0*) (int)
pci.subsys_product_id = 17776 (0x4570) (int)
pci.subsys_vendor = 'Micro-Star International Co., Ltd.' (string)
pci.subsys_vendor_id = 5218 (0x1462) (int)
pci.vendor = 'nVidia Corporation' (string)
pci.vendor_id = 4318 (0x10de) (int)
Does the hardware support this (explicit control (e.g. via a script or
commandline) of whether the sound is going to the speakers or to the
headphone even when the headphone is plugged in.)
If the hardware supports it, how would I, in fact, switch via
commandline between the two outputs?
Thanks in advance
Eric Holstege wrote:
> It appears that when I have a headphone plugged in, the speakers are
> automatically disabled and the output sound is sent to the headphone.
> However, I want to explicitly control (e.g. via a script or
> commandline - not a GUI) whether the sound from an (arbitrary)
> application is going to the speakers or to the headphone even when the
> headphone is plugged in.
> (When I say "arbitrary application" that means I can't alter the code
> of the application itself).
> Is this possible?
> (I have heard that ALSA mutes the speakers when it detects plugged-in
> headphones. Is switching between them as simple as using e.g.
> amixer(1) to unmute the speakers and mute the headphones and vice
> versa, or is there more to it.)
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