On Monday 20 February 2006 20:37, Robert Kulagowski wrote:
> > Got the same problem here as a result of a Gentoo update to 0.4.2.
> > Like many, I'm using it with Mythtv so there may be some issue with
> > ioctl differences fro m0.4.0 to 0.4.2. I upped to a 2.6.15 kernal
> > at the same time. This is on a PAL pvr150.
> >
> > Sounds to me like a pre-amp being overdriven - definite clipping
> > 'fuzz box' (shades of the 60's) sort of sound.
> >
> > I've made another observation - if I change channel to a tuner
> > input and then back to the s-video (so I'm using the external audio
> > input again) then the audio is fixed. If I just enter LiveTV on
> > Mythtv (so it goes straight to the last channel selected) then the
> > audio is duff again!!
>
> Do any of the devs have input on this?  I'm going to try 0.4.3 since
> it's been release to confirm if this is still an issue.

I'm getting the impression that it is not too difficult for someone to 
find the cause. Especially if switching input fixes the problem. The 
datasheet of the cx25840 is available here: 
http://dl.ivtvdriver.org/datasheets/video/

Only a few registers are changed by switching inputs, so it cannot be 
too difficult to find it.

I personally have never noticed it, and I unfortunately do not have the 
time to investigate either.

So I'm hoping someone can step in and try to find the cause. I'm willing 
to help with tips and advice and such.

The easiest way to start would be to add debug messages in the places 
where registers are set (cx25840_write and cx25840_write4) and see 
which regs turn up when you switch inputs to fix the tinny audio. Then 
check the datasheet to see what those registers actually do.

Regards,

        Hans

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