2009/6/19 Takashi Iwai <tiwai@xxxxxxx>: > Hi, > > this is yet another topic I'm (currently) working on -- the addition > of PCM ioctls to get/set some extra attributes. Basically, it adds > two simple ioctls for getting/setting extra attributes to the PCM > substream. The attribute has a sort of TLV form, > How is the association done between the pcm and the control? I would have thought an easy approach could be (from userland): snd_pcm_open( snd_pcm_t **handle, ...); snd_pcm_get_attr( handle, int attribute_id, *attributeX ); snd_pcm_set_attr( handle, int attribute_id, *attributeX ); I.e Use the snd_pcm_t handle from the snd_pcm_open call to query and set any controls associated with the pcm. We could then remove those controls from being viewable in alsamixer and leave it to the application to control them. The only controls left in alsamixer would then be the global controls. E.g. Speaker arrangement, master gain control etc. The result being that applications would never need to access the alsamixer controls, and instead only need to use the snd_pcm_get/set_attr interface on a per PCM basis that is much more in line with what applications actually need. >An important note is that I'm planning to use this framework for >getting/setting the PCM (surround) channel mapping. Why would we want this channel mapping info in user space? Can't we just standardize on a single channel mapping as seen from user space, and get the driver to do any adaption if needed? Kind Regards James _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
