[mythtv-users] HDTV digital static with DVB

[ffrr]

Preston Crow wrote:

>On Tue, 2005-11-08 at 17:14 +1000, ffrr wrote:
>  
>
>>I chased video glitches from my DVB setup for ages, and with a lot of 
>>help from the list, I finally nailed it.  It was the Si 3112  SATA 
>>controller chip doing nasties on the PCI bus and corrupting the mpeg 
>>stream from the DVB card.
>>
>>This would correlate with your observation that it is worse with
>>system load, in particular disk access.
>>    
>>
>
>Not only that, but I bought a new SATA drive at about the same time as I
>switched to the DVB drivers.
>
>Did you ever get a good resolution?
>  
>
Yep, swore long and loud at the manufacturers of such shoddy hardware 
:-) , then built a whole new dedicated Knoppmyth system on an old 850MHz 
box, using a 250GB IDE drive I went out and purchased.

Absolutely perfect recordings every time now !



>I have an ASUS A7N8X Deluxe motherboard, which includes on-board a
>Silicon Image Sil 3112A controller; the same one you found to be your
>problem.
>  
>

Yep, many people have since told me horror stories about them.

>I suppose that if I can't fix some setting somewhere, then my best hope
>is to buy a separate PCI SATA card with a different controller chip;
>that would at least be cheaper than buying a new 400GB hard drive.
>  
>



Well, what initially happened was, I was getting corrupt file systems 
frequently.  When I realised it was the controller, I found a BIOS 
update that included/added a parameter to extend some obscure timing.  
This had 4 setting from memory, something like 10us, 20us, 30us, and 
1ms.  That rang alarm bells as the doco said to try the first 3 and if 
corruption still occurred, set it to 1ms.  This is soooo much larger, 
but guess what.  I needed it set to 1ms to get reliable hard disks.  

I am 99% sure that this new setting made my DVB glitches much worse.  I 
hadn't really noticed them before, as I think they were so infrequent, I 
just put it down to signal noise.  But now, they were intolerable. (This 
was all using Mythtv under a Mandriva 2005le install)

I built a quick Knoppmyth install on an old 15GB IDE drive I had around, 
and with the Sata drives disconnected, and obviously all other hardware 
still the same, I had perfect pictures.  This is the point that I built 
the separate, non-SATA machine.

I still use the SATA machine as my daily desktop, and it is now 
reliable.   Just no good for DVB cards.