On 2007-02-11 03:06 +0100, Victor Hahn wrote:
> when trying to record using a microphone and an nForce3 on-board
> sound chip (Alsamixer says: Card: NVidia CK8S Chip: Realtek
> ALC850 rev 0), I always get a high pitched noise that drowns out
> the mic signal. The noise is nearly perfectly sawtooth-shaped
> and mostly takes exactly half of the spectrum (e.g. from 0 to
> +1 or from 0 to -1). I attached a wave file with a sample of
> this. When switching the mic physically on or off (or
> connecting/disconnecting it), the noise often flips from one
> half of the spectrum to the other. I'm using a dynamic mic that
> works flawlessly on other equipment.
>
> I'd appreciate if anybody has an idea what to do about this
> somewhat strange problem.
Similar situation here.
A signal into the line in socket does not appear in the mix. I.e.
the signal is not present on the line out socket.
Trying to capture the line in gives a somewhat irregular 4150 Hz
upward sawtooth. Reading signed 16-bit samples from /dev/dsp
returns values between about 0 and 1000, never negative. Whatever
signal is present on the line in socket has no effect. What you
read from /dev/dsp is just the sawtooth. This is in mono at 44.1
kHz.
A signal into the mic in socket *does* appear in the mix. I.e. the
signal *is* present on the line out socket.
Trying to capture through the mic input gives whatever signal is
present at the mic input multiplied by the sawtooth described
above. That is multiplied, not added. What you read from /dev/dsp
is your signal AM'd by a 4.1 kHz sawtooth !
Setup :
- Motherboard MSI K8N Neo4 Platinum (nForce 4).
- alsamixer says "Card: NVidia CK804" and "Chip Realtek ALC805 rev 0".
- $ lspci
00:04.0 Multimedia audio controller: nVidia Corporation CK804
AC'97 Audio Controller (rev a2)
- $ lspci -n
00:04.0 0401: 10de:0059 (rev a2)
- Kernel 2.6.18.2 from kernel.org.
--
André Majorel <URL:http://www.teaser.fr/~amajorel/>
Do not use this account for regular correspondence.
See the URL above for contact information.
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