[linux-dvb] Cam Menu?

David Härdeman david at hardeman.nu
Mon Oct 30 20:32:27 CET 2006

On Mon, Oct 30, 2006 at 07:07:05PM +0000, Andrew Lyon wrote:
>>On Mon, Oct 30, 2006 at 04:19:09PM +0000, Andrew Lyon wrote:
>>Also make sure you use recent drivers from the dvb repo, a patch I wrote
>>was committed a day or two ago, and without it, my CAM would lock up by
>>simply using a remote control (which would in turn produce lots of
>>interesting error messages).
>I am using a Technotrend S-1500 + CI + CAM, Ive not had errors when
>using the remote, but I do get problems with my card/cam if I change
>channels too quickly, and sometimes if i just leave myth running in
>the main menu, when I watch tv it always gets lock, but I get a blank
>screen for a long time and eventually a video error or I have to kill
>mythfrontend, stopping the backend, removing and reloading budget_ci
>and restarting the backend usually cures it, I ended up adding a menu
>item for that but its not a nice solution :(.

I have more or less the same problems. I spent some time last week 
debugging it but I didn't get that far.

>Really not sure what is wrong, I can leave it playing a encrypted
>channel for days at a time, but if I change channels a few times it
>stops working, I have a feeling perhaps the cam is not responding
>quickly enough to commands, are there any timeout values I could try

If you're feeling adventurous, you might try recompiling MythTV. In 
mythtv/libs/libmythtv/dvbcam.cpp, function DVBCam::CiHandlerLoop(), 
there is a usleep(250) which I suspect is way to low. The CI 
specification (EN50221) says it's fine to poll every 100ms, so try 
setting it to 90000 or so (this ain't 100% correct because MythTV might 
still want the shorter timeout to read replies etc...but it's a start if 
you want to spend some effort debugging).

Additionally, you might want to change 
mythtv/libs/libmythtv/dvbdev/dvbci.cpp, find the line in the beginning 
that says:

static bool DebugProtocol = false;

and change it to

static bool DebugProtocol = true;

which will give you much more debug info if/when the card acts up.

>My dvb-s card (Avermedia 777) and Freeview channels do not have the
>same problem.

It seems very dependent on the CAM that you're using. I'm using an 
AlphaCrypt with 3.09 firmware, which seems extremely picky. For 
instance, I was earlier using an extra long cable to connect the CI 
board with the C-1500 board, and that caused constant lockups and errors 
(within seconds, cammenu was barely useable) and things improved when I 
used the original (shorter) cable again.

I'm going to spend more time debugging my C-1500 when I have some more 
time to spend :)

David Härdeman

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