Subject: audio channel support
To: None <tech-kern@netbsd.org>
From: Reinoud Zandijk <reinoud@netbsd.org>
List: tech-kern
Date: 01/06/2005 02:06:28
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Dear folks,
when trying to test my new auixp(4) driver (commit pending) i've stumbled
against linux code that uses the SNDCTL_DSP_GETCHANNELMASK ioctl call that
is not part of the official OSS standard. The result of the
SNDCTL_DSP_GETCHANNELMASK ioctl is a value that has bits set for each
speaker that is available so programs can determine what audio support
there is.
In trying to fix this piece of code (in vlc... not yet dared to touch the
compat code ;) ) i've noted that NetBSD doesn't support querying or setting
speaker preferences. I.e. i can't setup my system for quadrophonic audio or
for dolby 5.1 by default.
Since auixp(4) can support mono, stereo, quadraphonic or dolby 5.1 (and
SPDIF... only not implemented yet) wouldn't it be more `sane' to have the
userland setup my stereoset settings (say quadraphonic) and let the kernel
report it doesn't have dolby 5.1 available since - although the chipset
supports 5.1 i `only' have quadrophonic audio available?
Next to that, would implementing the missing linux ioctl call be a good
idea? That would give allmost all linux programs that do support more than
stereo automatic access to dolby 5.1 audio since most programs i've seen
seem to rely on this call being present if more than stereo is requested.
Cheers,
Reinoud
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