[mythtv-users] Very poor picture quality from HD3000

[voidtrance at comcast.net]

The numbers are from the the little dialog that pops up in mythtv-setup during the 
channel scan. Both signal strength and S/N are in percent. 
It could be that the bar that represents S/N means db (so 13db, if that makes any 
sense - I am not a signals guy) but the character after the bar is '%'. 

----- Original Message ----- 
From: "Brian Wood" <beww at beww.org> 
To: "Discussion about mythtv" <mythtv-users at mythtv.org> 
Sent: Tuesday, September 22, 2009 3:04:04 PM GMT -08:00 US/Canada Pacific 
Subject: Re: [mythtv-users] Very poor picture quality from HD3000 

On Tuesday 22 September 2009 14:25:27 voidtrance at comcast.net wrote: 
> I am using the latest MythDora 10.21 (kernel 
> 2.6.27.30-170.2.82.fc10.x86_64) and I am seeing an extremely poor quality 
> of the picture coming out of my HD3000. For a comparison, I am using the 
> exact same cable to the TVs digital tuner and there I am getting a good 
> picture and sound. 
> 
> During the playback from the HD3000 (LiveTV, I have not tried a recording 
> yet), I get the following errors in the mythfrontend.log file: 
> 
> 2009-09-21 20:33:52.943 [mpeg2video @ 0x7f049ac07a00]Warning MVs not 
> available 2009-09-21 20:33:52.995 [mpeg2video @ 0x7f049ac07a00]ac-tex 
> damaged at 48 4 2009-09-21 20:33:52.996 [mpeg2video @ 0x7f049ac07a00]ac-tex 
> damaged at 40 5 2009-09-21 20:33:52.996 [mpeg2video @ 0x7f049ac07a00]ac-tex 
> damaged at 38 8 2009-09-21 20:33:52.996 [mpeg2video @ 
> 0x7f049ac07a00]invalid mb type in B Frame at 41 9 2009-09-21 20:33:53.041 
> [mpeg2video @ 0x7f049ac07a00]invalid mb type in P Frame at 54 38 2009-09-21 
> 20:33:53.041 [mpeg2video @ 0x7f049ac07a00]ac-tex damaged at 26 39 
> 
> I am not seeing any errors in the backend log during the playback. 
> 
> I have read that this could be due to poor signal quality or high S/N 
> ratio, so here is what mythtv-setup scan shows: when mythtv-setup finds a 
> channel, it is usually at signal strength of 94-96% and S/N ratio of 13%. 

Where are you getting those numbers? S/N is usually represented as a ratio 
(db.), not a percentage. Percentage of what? What is 100% S/N? No noise at 
all? Impossible. 

I know the signal strengths reported by some cards can be misleading, I've 
heard some cards do not really implement that feature, and indicate the same 
strength no matter what is fed to them. I'm pretty sure the HD-3000 is one of 
those, though it may have been the early drivers and not the card itself. 

-- 
Brian Wood 
beww at beww.org 
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