2010/6/7 Sebastian H. <vand2@xxxxxx> > Am 07.06.2010 05:37, schrieb Raymond Yau: > >>> 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 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
