[linux-dvb] VDR: Tuning stability

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

In order to make channel tuning more stable I have extracted
the code that VDR uses to change channels and made a small
test example that does nothing else but switching channels
(so basicly it does some "heavy zapping").

The file can be found at

  ftp://ftp.cadsoft.de/pub/people/kls/ctest.c

Please download and compile this file with

  g++ ctest.c -I../DVB/ost/include

and run the resulting executable. It will switch the channel every
3 seconds (which is probably slower than a real "zapper" would do).
I have only tested the sat version myself, but it should also work
with cable (I hope).

This works fine for a while, but at some point error messages start
to come up and the tuning operation fails. This gets even worse until
there are "outcommand error 1" and "ARM RESET" messages in the log file.
After an "ARM RESET" the test program just hangs, and once it starts
issuing "channel not sync'ed!" errors, subsequent channel switchings
are most likely to fail, too, and not even closing and re-opening all
files helps - until at some point it suddenly works again.

I see two possibilities here:

1. My tuning code is flawed and doesn't do things the way the
   driver expects them to be done. In that case I would appreciate
   and advice on how to do better.

2. There is a problem in the driver/firmware. In that case maybe the
   driver developers can use this test program to track down the
   problem and solve it.

I believe the channel switching operation - besides error free recording
and replay, which I am currently also working on - are the two most
important functions of VDR (or any set-top box/digital video recorder,
for that matter), so it's about time we get this to work more stable
and reliable.

Klaus
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


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