Hans Verkuil wrote: > 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 updated from 0.4.0 to 0.4.3 and have the issue now on my PVR-500. > > 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. What I found out though is that in myth, if I set the recording volumes to be ~80% the audio is OK.
What I also noticed was that the volume on my PVR-350 was quite a bit lower than 0.4.0 and remember that people were complaining of the reverse and a change being done to fix this. So maybe that same change that brings up the volume on the 150/500 for some is the one that causes the tinny audio for others. If I get some time, I'll try tracking this down but my work schedule is so crazy (Silicon Valley startup) that I can't promise anything. Regards, Dejan _______________________________________________ ivtv-devel mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-devel
