[pvrusb2] Bad video quality on PVR-350 and HVR-1950

[Mike Isely]

On Thu, 14 May 2009, stan schultz wrote:

> I had problems with my new HVR-1950 with FC10 and MythTV a few months ago.
> The way we left it was that it was probably a problem with the tuning table
> for the 1950 in my app (mythtv).  As I was using mythtv, it doesn't make
> sense that the app is wrong (I think).  But I temporarilly gave up on the
> 1950, and am lookng at my old PVR 350.  I have a "similar" but not as bad
> effect on the PVR-350.  This problem is not as bad on the 350 as the 1950.
> Both are Analog, not Digital TV.  And, as you remember, the video input from
> my camcorder via the 1950 worked great with no artifacts.  Do you have any
> ideas?  A video clip showing the bad video can be found at
> http://home.wbcable.net/~schultz/ .
> 
> Thanks,
> 
> Stan

The color is perfect, audio is fine, and you've got a really solid 
vertical sync lock.  The only trouble I see is some intermittent ripping 
that looks to be caused by trouble with horizontal sync lock.

Honestly to have everything else so perfect really says that the 
hardware is probably fine.  The logic which handles vertical and 
horizontal sync locking is all inside the same piece of silicon so it 
should be an all-or-nothing thing.

I concur with Roger.  I think you might have a source of interference 
nearby.  I believe the PVR-350 uses an SAA7115 for video capture which 
is a much older part than the cx25840 used in the HVR-1950.  They could 
be reacting to the interference in different ways.

If you have a VCR, you could try connecting its *RF* output to your 
HVR-1950 and then doing a capture on channel 3 (or 4 or whatever the VCR 
sends on).  By using the RF pathway you'll be doing the same scenario 
which is causing you problems right now.  If it is really caused by 
interference then this closed-circuit setup should be immune.  Obviously 
this isn't your solution but it would yield a useful clue.

  -Mike

-- 

Mike Isely
isely @ isely (dot) net
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