sporadic cablecard problem

ginolee · 10-03-2006, 09:38 PM

About 2-3 times a week, one of my 2 cablecards develops a 'CP Authorization Error' and won't tune the encrypted channels. Restarting my Tivo resolves the issue, but obviously this is not an acceptable long term solution.

Even with the 'CP Authorization Error' (Tivo->Settings->Cablecards->Configure cablecard 1 or 2 -> CP Screen), it seems to continue to record the network HD channels fine in this condition, which is a bit of welcome news.

Can someone write up a one or two page specification of how cablecards work and post it here ? I'm not keen on digging through the hundreds of pages specs at the cablelabs site.

I'm trying to ascertain whether this is a cablecard problem or a Tivo problem.

Thanks,

. By the way, other than this really annoying sporadic issue, I'm about 95% happy with my Tivo Series 3.

Gino.

Goofball · 10-03-2006, 11:51 PM

I missed this when I was looking earlier before I made my post here:
http://www.tivocommunity.com/tivo-vb...d.php?t=320259

My problem is similar but my cards show authorized but don't pick up the ECMs needed to decrypt the channels.

Who is your cable provider and what manufacturer cards are they using?

jfh3 · 10-04-2006, 12:14 AM

Already trying to do that based on a number of other problems that may be related to CableCARDs. Unfortunately, Tivo engineering is swamped at the moment.

When you see this problem, try going into Test Channels and tuning an encrypted or premium station and then look at the CableCARD status again - does the status go back to normal?

ginolee · 10-04-2006, 12:44 PM

my cable provider is Cablevision.

my cablecards are manufactured by Scientific Atlanta.

I will try jfh3's suggestion next time I get this 'CP Authorization Error'. Although, I'm pretty sure I've tried it and it doesn't fix it. Restarting my Tivo always fixes the issue.

I wonder if Tivo invokes some kind of initialization function on each cablecard on restart.

If so, one thing Tivo might want to implement is logic like the following:

If recording from a cablecard on an encrypted channel and no feed is coming in for 2 minutes, send the initialization request to the cablecard, wait 2 minutes and check the channel again to see if that fixed it. Losing 4 minutes of a channel is preferable to losing the entire show.

Also add an option to invoke initialization of a cablecard without having to restart the Tivo. Each Tivo restart takes about 5 minutes, so I'd like to avoid this full restart as much as possible.

Gino.

ginolee · 10-04-2006, 11:17 PM

I've encountered the 'CP Failure' error again tonight while I started to watch 'Boston Legal'.

I can tune to network channels fine but not channels like SciFi or HBOHD. I get a blank screen on those channels. Tivo restart resolves the 'CP Failure'.

1) Could this be a timing issue, where the CPU is slow to regen the keys ? It's interesting that the CP failure has occurred at least a couple times for me while I was doing a playback. What's interesting about this is that Tivo must be doing three things simultaneously: recording the 30 minute buffer for each tuner, plus playing back a third recording. When Tivo has to regen the cablecard key(s), this would add a fourth task for it to do. And if the key refresh rate is the same for both cablecards, this might actually be two tasks -- regen keys for both cablecards almost simultaneously.

What's interesting is that restarting my Tivo always resolves my 'CP Failure'. So I think the following engineering trick might alleviately the issue:

If Tivo detects a 'CP failure', have it try to regen the CP key for the problematic cablecard at least 2 more times before giving up.

This may help because if Tivo is trying to generate CP keys for both cablecards simultaneously plus recording two live buffers plus playing back a third record, it may get temporarily overloaded CPU wise. In every CP Failure case I've encountered only one of the cablecards has run into it at a time.

So, if Tivo tries to regen the CP key for the failed cablecard 2 more times, I think there's a chance this may reduce the effective CP Failure error rate down to 0.

Gino.
Senior Software Developer.

Brainiac 5 · 10-30-2006, 07:04 PM

I am having the exact same "CP Failure" problem, which can be cleared up by rebooting the TiVo. My CableCARDs are also Scientific Atlanta.

Another interesting thing, which may or may not relate to Gino's theory: For a while I was using only one CableCARD (because the installer only brought two, and one of them didn't work). I may have just been lucky, but during that time (about a week), I did not experience this problem. Now that I have two cards, it happens about 2-3 times a week, just like for Gino. The problem may occur on either card, so it's not just that card 2 has a problem.

I'll also try jfh3's suggestion next time it happens and report back.

Brainiac 5 · 10-30-2006, 07:28 PM

As luck (?!) would have it, immediately after posting I turned on my TV and was greeted by a blank screen. Checked the "CP Screen," which said "CP Failure."

So, I tried what jfh3 asked about. I went to test channels, and could not tune any encrypted channels - they're just blank. I played with it for a while, during which time other odd things happened: I couldn't tune unencrypted channels either at first, but after a few seconds and a few channel up/downs they started working; my channel information went away for a while (it said something like "no channels") then came back.

I figured that if I couldn't tune the encrypted channels, it wouldn't have fixed anything, but just in case I got out of the test channels screen and returned to "CableCARD Menu" -> "CP Screen." It still said "CP Failure."

jfh3 · 10-30-2006, 08:53 PM

Quote:

Originally Posted by Brainiac 5

As luck (?!) would have it, immediately after posting I turned on my TV and was greeted by a blank screen. Checked the "CP Screen," which said "CP Failure."

So, I tried what jfh3 asked about. I went to test channels, and could not tune any encrypted channels - they're just blank. I played with it for a while, during which time other odd things happened: I couldn't tune unencrypted channels either at first, but after a few seconds and a few channel up/downs they started working; my channel information went away for a while (it said something like "no channels") then came back.

I figured that if I couldn't tune the encrypted channels, it wouldn't have fixed anything, but just in case I got out of the test channels screen and returned to "CableCARD Menu" -> "CP Screen." It still said "CP Failure."

Sadly, sounds like you have a different problem.

Brainiac 5 · 10-31-2006, 02:09 PM

Quote:

Originally Posted by jfh3

Sadly, sounds like you have a different problem.

Quite possibly, yes...

However, the "other odd things" I mentioned happened just this one time - every other time, I've seen the exact same symptoms that Gino describes (right down to the frequency with which it occurs). So if there's a different problem, it unforunately sounds like that's in addition to having the same one.

I imagine it's also possible that the different than usual behavior (which lasted for only a short time) was because I caught it at just the "right" time (I think I got it right as the problem began) or some such reason.

I guess time will tell as I continue to watch for it...

dbenrosen · 10-31-2006, 02:45 PM

I have the exact same problem, and my cablecards are also SA. Cablevision is coming out for the 3rd time tomorrow to give me new cards. One of my cards seems to be working with the latest change, but the other one is dead. Rebooting always fixes the problem.

Brainiac 5 · 11-02-2006, 08:52 PM

I just got the chance to test the TiVo in this state again (lucky me). This time, nothing odd happened when I went to test channels, I just still couldn't tune anything encrypted. Going to an encrypted channel (which of course would not display) did not have any effect on the "CP Status."

Brainiac 5 · 11-02-2006, 08:55 PM

Quote:

Originally Posted by dbenrosen

I have the exact same problem, and my cablecards are also SA. Cablevision is coming out for the 3rd time tomorrow to give me new cards. One of my cards seems to be working with the latest change, but the other one is dead. Rebooting always fixes the problem.

When you say one is working, does that mean that you're not seeing the problem on it? And does that also mean that you only have one card in the TiVo right now?

I previously had only one card in my TiVo for about a week, during which time I did not see this problem. However, after adding a second card, the problem now occurs on BOTH cards.

dbenrosen · 11-15-2006, 02:32 PM

Quote:

Originally Posted by Brainiac 5

When you say one is working, does that mean that you're not seeing the problem on it? And does that also mean that you only have one card in the TiVo right now?

I had both cards in my TiVo, but only one card was showing the problem and the other one was working fine. After the 3rd time replacing cards, and wasting another 3 hours of my life on this, I called TiVo and they sent me a replacement unit.

When the new T3 came:

I took the cards out of my original T3 and went through the install with Cablevision on my new T3. Another wasted hour, but both cards were working. That lasted about 11 hours, when the card that was working in my original T3 had authorization fail. A reboot of the new T3 brought authorization back, but this is unbelievably frustrating and totally unacceptable.