Am 29.11.2013 17:22, schrieb Tanu Kaskinen: > On Fri, 2013-11-22 at 18:34 +0100, Oleksij Rempel wrote: >> Am 22.11.2013 17:48, schrieb Tanu Kaskinen: >>> On Thu, 2013-11-21 at 16:42 +0100, Oleksij Rempel wrote: >>>> Hello all, >>>> >>>> i posted this email to ALSA, but probably PA devs have some ideas too. >>>> >>>> ====================================================================== >>>> Hello Takashi, >>>> >>>> what is acceptable noise level for mic boost? >>>> My laptop has three levels of mic boost (+36dB). Level 3 is useless >>>> since noise level will be about 0db. With level 1 i get -12dB noise, so >>>> there is almost 12dB room for data... but it is not enough for normal >>>> speech, which is about 20dB. >>>> >>>> Are there any ALSA guide for HW designers, which will say some thing >>>> like acceptable levels are 90-20dB? >>>> There are some Skype and Microsoft prescriptions for certification. >>>> For example M$ prescribe 18dB or more for speech to noise ration for >>>> build in mics. It sound like good number to start. >>>> >>>> In my case, i need to remove mic boost completely to guarantee minimum >>>> 18dB SpNR. Suddenly i didn't found correct way to do it. >>>> I will be thankful for some tip. >>>> >>>> ===================================================================== >>>> >>>> So my question to PA devs. Do pulse audio need to know about noise level >>>> of microphone? Will it help to make correct decisions? Especial for VoIP >>>> and automatic gain control. >>> >>> We don't currently have any idea of the noise level, so we don't have >>> code for adjusting our decisions based on that information either. So, >>> I'd say that pulseaudio doesn't *need* to know about the noise level. Of >>> course, if someone someday complains that pulseaudio does bad decisions >>> because it doesn't take the noise level into account, then we would need >>> that information. >>> >> >> Thank you for your response. >> I have more questions: >> Skype continuously trying to adjust record level. > > I've never used Skype, but I think I've heard that it allows you to > disable the automatic gain control. I'd expect that to help with your > problem. Well, it is workaround but not fix. To make conference call we need automatic gain control. Disabling it will work only for single person call. The question is how to fix it? I tested 7 different notebooks, and 4 of them had this issue. It is nearly impossible for alsa to know about all of them. I'll snip other part of discussion. Right now it is less important. -- Regards, Oleksij
