[linux-dvb] Re: Avermedia 771 on Gentoo FIXED!

[Peter Henderson <peter.henderson@starjar.com>]

Kenneth Aafløy wrote:

On Wednesday 14 July 2004 04:16, Peter Henderson wrote:
  

I think I've fixed it.

There is an  integer underflow bug in mt352.c
need to change line 517 (based on rev 1.7 in cvs)
from
    tmp =  6 * freq + IF_FREQUENCYx6;
to
    tmp = ((param->frequency*6)/1000000) + IF_FREQUENCYx6;

This affects any multiplex which is on a Positive or Negative offset.
(So 4978333330Hz fails but 690000000Hz would be fine)

So Ben this should fix your problem as Crystal Palace is all Pos/Neg
offsets.
    

According to the datasheet (* p.44), this calulation is wrong. I've attached a 
patch which corrects this and also adds the requested change below. Please 
test a clean CVS with this patch, as I don't have this card/frontend/dvb-t.

  

I think you are mistaken.
Using the example on p44.
(and ignoring the IF_FREQUENCYx6 const for the moment)

Your code does..

param->frequency = 630166667
so
freq = param->frequency/1000000 = 630    <--- oops

630*6 = 3780
And the example is 3781


Where the change I made gives

(param->frequency*6)/1000000 = 3781

As  a side note.
Can FEC_NONE be added as a case to the LP code rate switch statements
(and probably the HP as well) as this was the original reason I couldnt
tune anything and had to comment out the default error return.
    

It will then default to FEC_1_2, is this okay?

Kenneth

* http://assets.zarlink.com/DM/MT352_Design_Manual_Nov03.pdf