On Mon, 2005-03-28 at 22:36 -0500, Lee Revell wrote: > On Mon, 2005-03-28 at 09:42 +1000, Benjamin Herrenschmidt wrote: > > It seems that Apple's driver has an in-kernel framework for doing volume > > control, mixing, and other horrors right in the kernel, in temporary > > buffers, just before they get DMA'ed (gack !) > > > > I want to avoid something like that. How "friendly" would Alsa be to > > drivers that don't have any HW volume control capability ? Does typical > > userland libraries provide software processing volume control ? Do you > > suggest I just don't do any control ? Or should I implement a double > > buffer scheme with software gain as well in the kernel driver ? > > alsa-lib handles both mixing (dmix plugin) and volume control (softvol > plugin) in software for codecs like this that don't do it in hardware. > Since Windows does mixing and volume control in the kernel (ugh) it's > increasingly common to find devices that cannot do these. You don't > need to handle it in the driver at all.
Yah, OS X does it in the kernel too lately ... at least Apple drivers are doing it, it's not a "common" lib. They also split treble/bass that way when you have an iSub plugged on USB and using the machine internal speakers for treble. > dmix has been around for a while but softvol plugin is very new, you > will need ALSA CVS or the upcoming 1.0.9 release. Ok. Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
