>>>>> I thinks Sebastian's question is whether he can use >>>>> snd_mixer_selem_set_playback_ >>>>> dB() set any values in between the volume steps >>>>> >>>>> e.g. Master volume control of ac97 is 1.5 dB per step, >>>>> >>>>> when using snd_mixer_selem_set_playback_dB() to set -0.9dB , how can >> the >>>>> mixer application know what dB value has been set since the value is in >>>>> between -1.5dB and 0dB without snd_mixer_selem_get_playbackdB() >>>> >>>> Indeed I quite happy with what ALSA already provides (I'm just an >>>> interested >>>> amateur). My main problem is that there is no documentation for the >> Mixer >>>> API >>>> and how things are related to each other. Like CTL, HCTL, Mixer and >>>> SimpleMixer and of course volume and dB in the snd_mixer_selem_ >> functions. >>>> >>>> The root issue is that I wondered if the mixer application should offer >> a >>>> separate text input for decibel values besides the text input for volume >>>> values. As pointed out this would not allow for finer grained volume >>>> control >>>> therefore for the moment I'll probably stick with a mere text label for >> dB. >>>> >>>> >> >>> The main difference between those volume controls using TLV_DB_SCALE and >>> TLV_DB_LINEAR is -6dB is at the middle of TLV_DB_LINEAR and TLV_DB_SCALE >> has >>> fixed dB value between any two steps. >> >> What's TLV_DB_SCALE and TLV_DB_LINEAR for? >> A grep in the alsa-lib sources did not return anything. >> >>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/332631 >>> >>> if the user has both hda onboard sound and emu10k1, he may notice that >> there >>> is big difference if he set volume at percentage instead of dB >> >> Interesting, that's my setup. I have an onboard HDA Intel and a >> pci SBLive! Card and some el cheapo USB sound cards to experiment >> with. Thanks I'll give the volume listening test a try at some point. >> > > > https://bugtrack.alsa-project.org/alsa-bug/view.php?id=4883 > > Pekka Lampila reported that when he set -40dB and only get back -9999999 by > his program alsa_mixer_test.c > > I don't have emu10k1 so don't know whether this is a bug of alsa-lib or not I also get a big jump from -39.60dB to -99999.99 dB for some emu10k1 sliders when I move them to the minimum although their advertised minimum is -40dB. This looks like a way to express log ( 0 ). (Sorry, I wrote this before with the wrong email address...) _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
