Audible clicks with ICH4 AC'97

martinko gamato at
Sun Jan 3 18:51:55 UTC 2010

Hi list,

I've upgraded from 6.4 to 8.0 and hoped that my long-time issue will be 
gone but no, I'm still experiencing the same audio distortion --
Playing music on FreeBSD reminds me of old tapes while listening to the 
same files on MS Windows produces no acoustic clicks etc at all.
Well, I cannot hear these clicks during music but throughout low volume 
passages they are quite audible and they stop when playback stops.

I still hope something can be done about it.
Any suggestions / ideas please ?




$ uname -a
FreeBSD mb-aw1n-bsd 8.0-RELEASE FreeBSD 8.0-RELEASE #0: Sat Nov 21 
15:48:17 UTC 2009 
root at  i386

$ pciconf -lv | grep -B 4 audio
pcm0 at pci0:0:31:5:       class=0x040100 card=0x18431043 chip=0x24c58086 
rev=0x03 hdr=0x00
     vendor     = 'Intel Corporation'
     device     = 'Realtek AC97 Audio  (82801DBM SoundMAXController 
(ICH4-M B0 step))'
     class      = multimedia
     subclass   = audio

$ cat /dev/sndstat
FreeBSD Audio Driver (newpcm: 32bit 2009061500/i386)
Installed devices:
pcm0: <Intel ICH4 (82801DB)> at io 0xffaff800, 0xffaff400 irq 5 bufsz 
16384 kld snd_ich [MPSAFE] (1p:4v/1r:1v channels duplex default)

$ sysctl hw.snd dev.pcm
hw.snd.feeder_rate_quality: 1
hw.snd.feeder_rate_round: 25
hw.snd.feeder_rate_max: 2016000
hw.snd.feeder_rate_min: 1
hw.snd.feeder_rate_polyphase_max: 183040
hw.snd.feeder_rate_presets: 100:8:0.85 100:36:0.92 100:164:0.97
hw.snd.feeder_eq_exact_rate: 0
hw.snd.vpc_reset: 0
hw.snd.vpc_0db: 45
hw.snd.vpc_autoreset: 1
hw.snd.latency_profile: 1
hw.snd.latency: 5
hw.snd.report_soft_matrix: 1
hw.snd.report_soft_formats: 1
hw.snd.compat_linux_mmap: 0
hw.snd.vpc_mixer_bypass: 1
hw.snd.verbose: 1
hw.snd.maxautovchans: 16
hw.snd.default_unit: 0
hw.snd.version: 2009061500/i386
hw.snd.default_auto: 0
dev.pcm.0.%desc: Intel ICH4 (82801DB)
dev.pcm.0.%driver: pcm
dev.pcm.0.%location: slot=31 function=5 handle=\_SB_.PCI0.AUDI
dev.pcm.0.%pnpinfo: vendor=0x8086 device=0x24c5 subvendor=0x1043 
subdevice=0x1843 class=0x040100
dev.pcm.0.%parent: pci0
dev.pcm.0.eapd: 1 4 fixed 48000 s16le:2.0
dev.pcm.0.rec.vchans: 1
dev.pcm.0.rec.vchanmode: fixed
dev.pcm.0.rec.vchanrate: 48000
dev.pcm.0.rec.vchanformat: s16le:2.0
dev.pcm.0.buffersize: 16384
dev.pcm.0.bitperfect: 0
dev.pcm.0.ac97rate: 48000
dev.pcm.0.wake: 0

$ mixer
Mixer vol      is currently set to  75:75
Mixer pcm      is currently set to  25:25
Mixer speaker  is currently set to  40:40
Mixer line     is currently set to  75:75
Mixer mic      is currently set to   0:0
Mixer cd       is currently set to  75:75
Mixer rec      is currently set to   0:0
Mixer igain    is currently set to   0:0
Mixer ogain    is currently set to  50:50
Mixer line1    is currently set to  75:75
Mixer phin     is currently set to   0:0
Mixer phout    is currently set to   0:0
Mixer video    is currently set to  75:75
Recording source: mic

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