On Mon, 15 Jan 2018 14:49:38 +0100, Ricard Wanderlof wrote: > > > On Mon, 15 Jan 2018, Takashi Iwai wrote: > > > > Ok, my suggestion would be set MAX_DB_UPPER_LIMIT to 90 dB. 90 dB comes > > > out as 31622, which still is manageable when shifted up by VOL_SCALE_SHIFT > > > (= 16), fitting in a 32-bit int. Thus it works in MULTI_DIV_short() too, > > > where it is multiplied with the 16-bit sample value yielding an int. > > > > > > I'll try it out and prepare a patch. > > > > Well, but +90dB gain doesn't look like a normal usage pattern. Why do > > you have to use softvol plugin for achieving that specific purpose? > > The usecase we have actually calls for 55 dB of gain maximum, but I was > thinking that looking at the code the maths can actually handle 90 dB so > it would be good 'reasonable limit' - it's a nice round number and fits in > 16 bits (signed). > > The usecase we have is using digital MEMS microphones ((2S connected, > with no integral amplification) and when the sound source is far away, a > fair amount of gain can be needed. But why do you need 90dB? "Because it can" is no good reason to increase such a safe limit. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
