On Wed, 3 Dec 2003, James Courtier-Dutton wrote:Why is the OSS volume value kept for each application?
Hi,
The alsa keeps state of all mixer levels in alsa's internal format which has min,max info. So, for example if alsa has 0-31 levels, converting that to the OSS 0-100 range is easy with a simple calculation, but if an OSS app just does Volume++, the change will be lost in the conversion from OSS to ALSA to actually set the state. So, to work the way it should, OSS will have to cache all mixer state in OSS format, thus requiring 2 state tables.
E.g. OSS Volume(0-100) ALSA Volume(0-31) OSS = ALSA * 100/31;
0 0 1 0 2 0 3 1 4 1 etc.
So, if OSS Volume is 2, and the OSS application does Volume++, the OSS volume will be set to 3. but if OSS Volume is 3, and the OSS application does Volume++, the OSS volume will stay at 3!
I don't undestand. Actually we have volumes in OSS format (in the kernel's mixer emulation), because some applications simply does not work for reason as you described (++ or -- applied). Note that these values are valid per application (so the resolution is reverted to ALSA's when another application changes volume too much). I don't see any other way to do it.
Jaroslav
----- Jaroslav Kysela <[EMAIL PROTECTED]> Linux Kernel Sound Maintainer ALSA Project, SuSE Labs
Surely, mixer volumes should be globally stored?
Or does the OSS volume for one application only control the volume of the sound from that particular application ?
What about the mixer open/close transition? If a single application does: - open volume++ close ... open volume++ close
Will the OSS volume settings be reset from the alsa levels ?
Cheers James
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