On Thu, 2011-08-04 at 11:22 +0800, Lin, Mengdong wrote: > I want to ask a very basic question. Can these modules support > multiple instances? > > > > 1. Module-alsa-card > > For example, if my platform has 2 ALSA devices, will there be two > instances of module-alsa-card? The easiest way to check if a module is intended to be loaded multiple times is to look for the PA_MODULE_LOAD_ONCE() macro in the module's sources. If it's called with a FALSE, you know that the author intended for it to be okay to have multiple instances loaded. > 2. Module-echo-cancel > > And if more than one input/output stream need echo cancellation (just > for example), will there be two module-echo-cancel instances? The idea is the module applies to one sink/source pair at a time, and all streams that want to talk to that sink/source pair and need AEC should go through the virtual sink/source pair created by loading module-echo-cancel on top of the master sink/source pair. So if you have 2 devices which you want to run echo cancellation on, you load two instances of the module (module-filter-apply should do this for you). -- Arun
