6 Dec
2008
6 Dec
'08
5:58 a.m.
On Fri, Dec 5, 2008 at 12:03 PM, Harsha, Priya priya.harsha@intel.com wrote:
Hi,
If my sound card supports hardware mixing, how do I need to code my sound card driver such that I can send multiple streams through ALSA to the sound card driver at the same time?
Check out the emu10k1 driver. You need something like the voice allocator in that driver that assigns a hardware mixing channel or channels when ALSA asks the driver for a new PCM stream.
User space would open the same device multiple times (up to the hardware voice limit) and the driver manages the allocations. From userspace POV a hardware mixing device looks just like a single stream device, but it doesn't return -EBUSY when you open it multiple times.
Lee