[mythtv] [mythtv-commits] Ticket #3541: Backend Crashes When Recording From Mux A In The UK (Freeview / DVB-T)

Daniel Kristjansson danielk at cuymedia.net
Fri Jul 27 12:26:00 UTC 2007

On Fri, 2007-07-27 at 03:18 +0100, Allan Stirling wrote:
> MythTV wrote:
> > #3541: Backend Crashes When Recording From Mux A In The UK (Freeview / DVB-T)
> > Comment(by danielk):
> >  Can you try the attached patch?
> > 
> >  A long time ago it was reported to me that the cards with the "Philips
> >  TDA10046H DVB-T" frontend destroyed the CRC of their PMT tables and so we
> >  had to turn off error checking and risk crashes in order to support this
> >  card at all.
> > 
> >  However, a similar report was also filed about "DST DVB-S" cards, which
> >  I've  now tested myself and it does not exhibit the reported problem, at
> >  least with drivers produced in the last year. The attached patch turns off
> >  the "don't check and fly blindly" behavior in MythTV for all cards. If you
> >  can tune in channels at all with this patch applied, it will take me 5
> >  minutes to commit a proper fix.
> AFAIR, this was before we handled packets which (validly) 
> had no CRC.

It was, but this was reported to on the PAT & PMT sections.

> There is nothing that the frontend does that can change the 
> contents of the packets. The only card that could possibly 
> do something like this is the 'fully featured' technotrend 
> cards, which can (again, as far as I know) rewrite the stream.

What about cards with a CAM? I assumed this was due to a
faulty implementation of code which removes CA descriptors.
This would probably be firmware on the card itself; three
out of the four cards this problem was reported on were DVB-S
cards. In Europe, DVB-S cards with CAM's are popular to
receive subscription restricted satellite transmissions.

-- Daniel

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