At Thu, 29 Mar 2007 05:56:50 -0500, Nagalla, Hari wrote:
Hello,
I am new to ALSA, so some help from experienced folks would help..
We are trying to develop ALSA support for our DSP based mixer. In our architecture DSP performs the mixing, sample rate conversion etc. My question is how, can does the user space applications exercise controlling individual PCM stream to the mixer? Ex: individual stream gain control, individual stream mute, etc.. Any user space example code would be useful too..
Most drivers create PCM volume controls with IFACE_PCM tag, and set up the volume appropriately at each PCM open, or let alsa-lib configs to set up the initial volumes. Usually, the control element index corresponds to the PCM substream number.
The controls with IFACE_PCM are not visible from normal mixer apps. (The mixer sees only IFACE_MIXER elements.) So, if you need a dynamic control of such elements, you'll likely need a special program to access the corresponding elements.
Takashi