[linux-dvb] Re: cinergyT2: which kernel/usb module to use?

[Holger Waechtler <holger@qanu.de>]

John Dalgliesh wrote:

> On Mon, 29 Nov 2004, Klaus Schmidinger wrote:
>  
> > From an application programmer's view it really would be great if the driver
> > gurus could agree on a reference implementation of how exactly tuning
> > and waiting for a lock is supposed to be done...
> >    
> I must be missing something here, but where is it useful to wait for lock
> anyway - what's wrong with just waiting for some data to come through? I'm
> not having much luck imagining an application where the demod's internal
> idea of lock is any use waiting for, over just waiting for the actual
> data that you want to get out to arrive.
>  
It is not useful for anything, it just delays zapping. Ancient pre-v2 
av711x-drivers required this for some card versions because the driver 
did not shut down the PID filters when changing the demod parameter set 
and some early stv0299 chip revisions (or was it the 1893? don't 
remember for sure - ) did not muted the TS appropriately when running 
out of sync but crashed the MPEG decoder by feeding the av711x with 
garbled TS packets.

This was a hardware bug that was fixed in later chip revisions, and all 
recent DVB drivers have some ugly workaround code for these broken PCI 
cards (see the frontend notifier callbacks in dvb_frontend.c), so there 
is no need to do tuning and filter setup in a particular order anymore. 
You can simply set up all parameters and PID filters, start the MPEG 
decoder and then watch the signal status statistics in regular intervals 
if you want to display them in your OSD while rendering the video 
picture on the background plane.

Holger