Date: Thu, 04 Aug 2005 19:40:03 -0500 From: Harry Coin <harrycoin@qconline.com> To: Michael Nottebrock <lofi@freebsd.org>,freebsd-multimedia@freebsd.org Cc: Dev Mazumdar <front@4front-tech.com> Subject: Re: Upgrade, fix and new, maximal CS4236B chip support to mss.c available for testing Message-ID: <4.3.2.7.2.20050804193304.01f0eaf0@mail.qconline.com> In-Reply-To: <200508041950.55697.lofi@freebsd.org> References: <4.3.2.7.2.20050804120923.03827918@www.n4comm.com> <4.3.2.7.2.20050804120923.03827918@www.n4comm.com>
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At 07:50 PM 8/4/2005 +0200, Michael Nottebrock wrote: >All of that would definitely be very nice to have, but I'm not sure if OSS >currently provides the facilities to do that a generic way - I'm cc'ing Dev >Mazumdar of 4front who probably will know better. All it would take would be for the OS to adopt a convention that each step from 0 to 100 represents a fixed, driver dependant db change (usual case). It would be up to the device authors to specify the amplification at 0, and at 100, and helpfully to do the math so folk don't have to guess where 'flat' (0db) is in the 0 to 100 scale. (Also, with some more recent sound chips, and all that resolution, volume scales that offer 100 choices start to look a little coarsely grained (especially for recording/input mixing jobs). I'm sure this is old news, but sometimes the levels in mixers are actually attenuations for most of the scale, and small amplifications at the top. So 'flat' (0db change input to output) might map onto around 70, with 100 mapping onto +12db, and negative values below that. Also, in many sound chips, there are digital mixers that feed analog mixers in output sections, optional fixed (either flat or +xx db) boosts on mic inputs, and so forth. I mention this to show why there is just no way an OS can presuppose usable one size fits all default mixer values. Harry
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