Well, after doing quite a bit of testing with the new audio drivers
for 6.1, we have found some interesting issues with regards to
the SB16 and Geode/MediaGX support.
Generally speaking, the new drivers for old ISA cards do not seem
to work nearly as good as the old ALSA based drivers used to.
First off, when ISA DMA is enabled in the driver, the entire system
almost grinds to a halt when we play anything. If we play an Mpeg1
video clip with a 44.1Khz audio stream that played fine under 6.0,
the video starts totally falling apart and being unable to keep up under
6.1 with the new audio driver. If we start the sb audio driver without
DMA enabled, it still plays both video & audio quite nicely – but loses
the ability to maintain lipsync between the streams. It seems like the
legacy DMA subsystem is handled a bit differently under 6.1 but
I’m not sure if the difference is at the kernel and/or Dinkum level or
strictly in the new audio drivers.
Secondly, under 6.0, if we attempted to play a stream that was at
48Khz and the sound cards physical hardware only supported 44.1Khz
(i.e. like the SB16 and the Geode) then either the driver or PhPlay would
automatically subsample to (I assume) 24Khz and go ahead and allow the
audio stream to playback. Under 6.1, it simply returns and error message
and gives up. Once again, I don’t know if this is a difference in the new
version of PhPlay or in the new audio drivers themselves.
I understand that ISA is quickly dieing off, but these are both major
headaches for Geode based platforms – which are pretty well limited
to using the SB16 ISA drivers under RTP. And there are a LOT of
QNX based Geode platforms out there…and I’m sure we would all
like to do everything possible to help there be even more of them!
Is there any hope of either (a) this being looked at a bit up there or
(b) getting the SB16 ISA driver source released for the DDK?