[linux-dvb] VDR: Tuning stability

[Ralph Metzler <rjkm@convergence.de>]

Klaus Schmidinger writes:
 > 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.


OK, I tested the following:

- start ctest until it starts with "channel not sync'ed!" 

- exit ctest 

- start ntuxzap, tuning works fine

- exit ntuxzap

- start ctest, I immediately get "channel not sync'ed!" 

- exit ctest 

- start ntuxzap, tuning works fine

...


I did not get any outcommand errors yet. They are usually caused by 
a crash of the TPP (transport packet parser) hardware in the AV7110
caused by "bad tuning". I'll have to do more debugging to see if this
is the reason or if some bug in the firmware causes it.

In any case, the "channel not sync'ed!" errors seem to be an error
either in the higher level driver parts (QPSK/QAM event queue
handling) or the application. I'll have to take a closer look first.


Ralph


 








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