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Technotrend C-1500+Technotrend CI+Conax CAM

January 19, 2011 Leave a comment Go to comments

I finally received my Technotrend CI module + Conax CAM order. So now I have the following hardware working (with some minor tweaks below): Technotrend C-1500 + Technotrend CI module + Conax CAM. These are my software versions: Fedora 12, kernel 2.6.32.21-168.fc12.i686 and MythTV 0.23.1.

Initially, I had some issues with recordings sometimes failing with the following error message in mythbackend.log:

2011-01-18 21:48:18.268 PID 0x1f9c status: Encrypted
2011-01-18 21:48:18.798 PID 0x1f9b status: Encrypted
2011-01-18 22:00:07.363 PID 0x44d status: Encrypted

Once I got this message, all subsequent recordings failed. What I quickly discovered was that if I restarted mythbackend, then the recordings would start working again. There seems to be some issue with the CAM or mythtv going into an invalid state if the DVB card/CAM is kept open for a long time.

So I changed the following mythtvsetup options under “2. Capture cards“:

Open DVB card on demand -> turned on
Use DVB Card for active EIT scan -> turned off
DVB Tuning Delay (msec) -> 2000
Tuning timeout (msec) -> 5000

If you set these and use EIT data, make sure to set “Use quick tuning” to “Never” under “4. Video sources”. Otherwise you might not get any EIT data. Based on the description, it sounds that after this change you will only get EIT data when you are actually watching TV or recording…

Anyway, what I assume fixed the issue was that now the card is opened for each recording, and therefore the CAM is re-initialized. This triggers the following message in /var/log/messages at the start of each recording (when the card is opened):

Jan 19 17:00:02 xxx kernel: dvb_ca adapter 2: DVB CAM detected and initialised successfully

Since these changes I’ve had the card running for 18 hours and successfully completed about 20 recordings.

Update – status one week later: the card is quite stable and only 1 out of maybe 50-70 recordings has failed. It was related to a dvb read error (something I have never seen before with unencrypted data).

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  1. April 11, 2011 at 22:18

    Thank you for this post (and the whole blog as well). I have MythTV running on Ubuntu with the Technotrend T-1500 (DVB-T), CI and Conax CAM. Here in the Netherlands nearly all DVB-T channels are encrypted (Digitenne).

    I experience (I hope!) the same problem. Some recordings of encrypted channels fail. I will have a close look at it and when I’m sure that I suffer the same I will take the measures you describe.

    I get my program data from EIT, so I hope this will keep updating. I think it won’t be a problem if there is at least a recording every few days. I will probably install an extra USB-DVB-T receiver (for FTA only) and then you can tick cross source EIT.

    BTW Do you have experience recording multiple encrypted channels on the same ‘bouquet’ simultaneously? The T-1500 does this fine with unencrypted channels; tried up to three.

    • April 11, 2011 at 23:25

      Regarding your question about recording multiple encrypted channels from same multiplex… Yes, my experience is that you can record multiple encrypted channels at the same time if they are on the same multiplex. What multiplex channels are on depends on your provider. I can confirm successfully recording two channels at the same time using the setup above. I’m not sure if there is some limit depending on your hardware.

      To check which channels are on the same multiplex, run the following sql:
      use mythconverg
      select mplexid,callsign from channel order by mplexid;

      All channels that have identical mplexid seems to be recordable using the same tuner.

    • Octavian
      August 10, 2011 at 22:47

      I experience (I hope!) the same problem. Some recordings of encrypted channels fail. I will have a close look at it and when I’m sure that I suffer the same I will take the measures you describe.

      If you haev not found the issue it might be related to the CAM initialization. On the wiki page:
      http://linuxtv.org/wiki/index.php/TechnoTrend_TT-DVB-T_1500

      There is a simple patch for forcing a reinitialization. I am using that solution since 2007-2008 and never had a failure. Before I was having 50% chance of CAM init failure.

  2. April 20, 2011 at 20:41

    I noticed that some recordings of two shows on the same multiplex succeeded, while others did not. Strange… To be safe I set the number of tuners to 1 at this card.

    Your solution for recording encrypted shows worked, and I even got EPG data from the recorded channel. However, other channels on the same multiplex got no new EPG data.
    So I am now experimenting with the following script, which is run every minute from crontab (use at your own risk!):

    #!/bin/bash
    (
    host=`hostname`
    if [ `mythtv-status | grep “^$host” | grep -c “Recording”` -eq 0 ]
    then
    lastreset=0`cat /tmp/lastcamreset 2> /dev/null`

    now=`date +%s`
    ago=`expr $now – $lastreset`

    if [ $ago -ge 1800 ]
    then
    # reset!
    echo -n `date +”%F %H:%M Reset… “`
    echo $now > /tmp/lastcamreset
    echo -n `service mythtv-backend restart`

    # check the results
    sleep 10
    grep dvb_ca /var/log/messages | tail -1 | sed -e “s/.*://”
    fi
    fi

    Mythtv-status is a program which displays some statistics about the MythTV backends. I found it in the Ubuntu repositories.
    This script resets the backend (and with it the CAM) every half an hour when the backend is not recording. This is not my master backend.

    • April 20, 2011 at 22:09

      Interesting, I may know why you may not be getting EPG data. In the city I used to live, I noticed that my digital receiver couldn’t receive EPG data from other channels than the one it was recording. But when I moved to my current city, the digital receiver also started receiving EPG data for channels it wasn’t recording. This may be similar to your situation, maybe your provider only sends EPG data of the channel it is currently showing, and not for all channels…

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