On Mon, 08 Jan 2018 12:01:34 +0100, Petr Kulhavy wrote: > > Hi, > > does the ALSA library provide a method to set multiple channel values > of a multi-channel mixer element at once? It depends. If the multi-channel is implemented in a single control element, you can set the whole update and write it in a single shot. But maybe not via alsa-lib mixer functions but with raw snd_ctl_*() stuff. Takashi > There are the > snd_mixer_selem_set_XXXXX_all() methods, which set all channels to > the same value. > I would like to write a different value to each channel, is there such > a method? > > My motivation is the following. I have a HW with DSP/equaliser > function, which uses a 5-channel mixer element (volume type element) > to store biquad coefficients. > To avoid invalid values in the transfer function the coefficients have > to be sent to the HW over I2C all together in one transfer. Though the > low level driver does that, the snd_mixer_selem_set_playback_volume() > API method I'm using sets only one coef at a time. > This results in partial updates of the biquad coefficients and > temporary errors in the transfer function. > > Thanks > Petr > > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxx > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
