[vdr] Re: Experiences with patched VDR 1.2.x (was Re: [PATCH] Old descriptorh

["Dr. Werner Fink" <werner@suse.de>]

On Tue, Sep 30, 2003 at 10:36:09AM +0200, Martin Holst wrote:
> Christian Jacobsen wrote:
> > Hallo,
> > 
> > >In my case, if a UPT-Error occur, I only get a disturbed picture and no
> > >restart. Have you added an EmergencyExit within remux.c if the UPT-Error
> > >occur?
> > >Nevertheless, I think there are different effects which trigger a
> > restart:
> > >- UPT-Error (if you added an EmergencyExit in remux.c)
> > >- video data stream broken
> > >and several other things. The first case is probably solved with the
> > patch
> > >and the second is (at least for me) solved with disabled EPG-scan (0 in
> > >settings/EPG).
> > 
> > The second problem is maybe be the caused by Interferance between the
> > DVB-s cards (I am no expert - just my observations and thoughts ;)) - see
> > my mail "UPT-Error = interferance betw. DVB-s cards ?" - just send before
> > this.
> 
> This morning I noticed a "video data stream broken" even with disabled
> EPG-scan. So that doesn't help. :-( Nevertheless since 5 days I've no UPT-Error
> within live-view and several recordings. So I think my patch help us in that
> situation. Further tests will give us more information...
> 
> The "video data stream broken" occur on my machine (and on another with 2*
> DVB-s 1.3) since vdr 1.0.x on (only) the secondary card. So I don't know, how
> to track this in the source code. 

Let's read a comment within dvb_frontend.c:

[...]
/**
 *  if 2 tuners are located side by side you can get interferences when
 *  they try to tune to the same frequency, so both lose sync.
 *  We will slightly mistune in this case. The AFC of the demodulator
 *  should make it still possible to receive the requested transponder 
 *  on both tuners...
 */
static
void dvb_bend_frequency (struct dvb_frontend_data *this_fe, int recursive)
[...]

> What is the difference between the primary and the secondary device-handling
> within VDR? I don't believe that the driver himself handle the cards in a
> different way. 

I's suppose that it could be that if two cards tune to the same frequency
you'll may see "video data stream broken" ... maybe the workaround
in dvb_frontend.c isn't good enough.   IMHO VDR should avoid to tune
two cards onto the same frequency/transponder.

On the other side. How the two cards are connected to the LNB. Is
a multiswitch used?  Then the question rises: which multiswitches
may cause such interferences which results to wrong frequencies
(Schwebung, Seitenbaender).  Are there multiswitches which do
_not_ show this behaviour?


      Werner


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