Am Mi 15. April 2009 schrieb Rask Ingemann Lambertsen: > On Sat, Apr 04, 2009 at 02:33:14PM -0700, Steve Mosher wrote: > > > Cédric Berger wrote: > > > > And if it is the buzz fix (by adding the cap) that causes potential > > > problems... what about the SOP currently applied to freerunners ? They > > > may be impacted by incorrect ALSA states ? > > Yes, that was a concern of mine as well, so this too had to be checked > > and verified. The complication being that a reworked A6 can only be > > distinguished AFAIK by visual inspection and not by checking a bit in > > the hardware. > > Perhaps you could turn on MICBIAS and measure for how long the current is > higher than normal as the capacitor charges. See "MICBIAS CURRENT DETECT" in > the WM8753L manual.
Alas there's no way to read back the results of "MICBIAS CURRENT DETECT", so this won't help. There's a way to detect buzzfix by rapidly switching on and off MICBIAS and testing if you "hear" some buzz when recording from builtin mic. Werner has created a small program to do the switching job. Anyway I'm thinking about tackling this issue from a different more radical vector: implementing a autocalibration scheme for mic sensitivity. This would involve creating a known sound level (e.g. by playback via speaker) and checking (and adjusting) the sensitivity of mic according to the audio level fed back to the mic. Advantage: independent of device hw revision / hw patch level. No need for creation and maintenance of device specific statefiles or other config data. Problem: needs check whether it can be done at all. cheers jOERG
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