Am Donnerstag, 20. Mai 2010 10:53:14 schrieb Raymond Yau: > 2010/5/20 James Courtier-Dutton <james.dutton@xxxxxxxxx> > > > On 19 May 2010 17:34, Sebastian H. <vand2@xxxxxx> wrote: > > > Hello everyone > > > > > > I'm working on an ALSA-Mixer application for C++/Qt4 and stumbled over > > > volume and decibel mapping for sliders. > > > My question: Is there always an 1 to 1 mapping from volume to decibel > > > and > > > > vice > > > > > versa or can there be decibel values in between two volume steps? > > > > There should be a one to one mapping. > > If the hardware has 200 steps on the volume scale, and those 200 steps > > are published to the user. > > With the dB scale, there will still be the same 200 steps in the dB > > scale. The dB information simply helps the user interface convert each > > step into a dB value. > > a stepping function is not continuous and this is why > snd_mixer_selem_set_playback_dB() cannot set decibel values in between two > volume steps That's clear. I imagined that maybe the dB scale could be the "real thing" and the volume steps would be a convenient but possibly coarse mapping into a denser stepped dB space provided by the hardware/driver. This was unlikely but I wanted to ask anyway ;-). _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
