Noise... was Re: [mythtv-users] PVR-350 and MythTV recording quality sample

[Kai Fritzowsky]

On Tue, Mar 15, 2005 at 12:15:35PM +0000, David wrote:
> Kai Fritzowsky wrote:
> >On Tue, Mar 15, 2005 at 10:33:07AM +0000, David wrote:
> >>>Right. Literally. But I've got some audible noise that I can't get rid
> >>>of. Is this an hardware issue or related to ivtv or mythtv? Anyone else
> >>>got this problem?
> >>No audio 'noise' (go and google for 'ground loop' though...)
> >My 'noise' clearly is not a ground loop. I know this 50Hz sound quite 
> >well.
> >It's more like the noise you can hear, when the tuner is not tuned. In
> >addition, I can even hear it when viewing recordings on my wireless
> >notebook. My VCR and TV receive perfect sound, so there's nothing wrong 
> >with
> >the signal.

> OK, what soundcard?
> Are you using ALSA?

Different sound outputs:
- FE/BE combo:
  PVR-350
- FE on notebook:
  Silicon Integrated Systems [SiS] SiS PCI Audio Accelerator (rev 02)
  using ALSA

> Does alsamixer (or whatever) show anything at full volume (including 
> recording levels) - for now make sure nothing is above 80%.

I played with all involved mixer settings which did nothing good or bad
apart from adjusting the volume.

> Are the cable connections clean? Plug and unplug them a few times to try 
> and ensure good electrical contact.

Yes, the connections are good. I used the same cabling connected to the VCR
to test the setup.

> Does a source recorded elsewhere (a known good mp3) play back cleanly? 

Yes, it does.
I can't test this with the PVR's tv-out but with the notebook. I tested
playing back the PVR recordings with xine which is noisy. I also tested
playing back other recordings with xine and it sounds good.

> (in which case it's a recording/sampling issue)
> or not (in which case it's at least a playback, maybe both issue)

/Kai