MythTV DVB Setup Guide Part 3

Compiled by Martin Smith
V0.20 March 2005 (For MythTV 0.17)

Additional Information

Kenneth Aafl°y sent me the following text on using MythTV with a Conditional Access Module to access encrypted transmissions. I don't have one of these devices as none of the transmissions I can access require them. Also note that not all PCI adapters have the necessary hardware to support them. He has also sent me a note on using the 2.6 kernel and the DVB drivers.

I suppose I should note that there are now some encrypted channels on DVB-T in the UK. I'm unlikely to be paying to see them though so I doubt I'll be playing with a CAM anytime soon.

Conditional Access Module Support

There is limited support for using a CAM in MythTV, limited as in; there is no support for the CAM menus (yet). When using a CAM to decrypt channels the CAM needs to know which channel to decrypt, so the ServiceID in the channel setup needs to be entered correctly.

When using a CAM you will receive something like this in your mythbackend log output:
Starting up as the master server.
2004-01-14 16:04:40 DVB#0 Using DVB card 0, with frontend STV0299/TSA5059/SL1935 based.
2004-01-14 16:04:40 DVB#0 Trying to tune to channel 99.
2004-01-14 16:04:40 DVB#0 Frequency: 11325000 Symbol Rate: 24500000 Pol: H Inv:Off
2004-01-14 16:04:40 DVB#0 Setting LNB: Tone OFF 18V
2004-01-14 16:04:40 DVB#0 Waiting for frontend event after tune.
2004-01-14 16:04:40 DVB#0 Status: CARRIER | VITERBI | SIGNAL | SYNC | LOCK.
2004-01-14 16:04:40 mythbackend version: 0.14.20040102-1
2004-01-14 16:04:40 Enabled verbose msgs : important general channel
This next line is important, as it tells you that mythbackend was able to open a connection to the CAM Slots.
2004-01-14 16:04:40 DVB#0 CAM Support initialized successfully.
2004-01-14 16:04:42 Found changes in the todo list.
This line will tell you that this type of CAM is ready to be used.

CAM: Conax 4.00e, 01, 0B00, 04B1

This line tells you that the required data has been sent to the CAM, and you should expect a picture very soon.
2004-01-14 16:04:45 DVB#0 Sending PMT to CAM in slot 1.

2.6 Kernel Notes

Kenneth sent me the following notes based on a problem people have been having:

"It has been mentioned before that you should not at all include the path of the linux-2.6 kernel include tree, that is private to the kernel. Either copy the files under include/linux/dvb to another directory structure with linux/dvb in it, and point mythtv to that. Or download the latest linuxtv driver package, and point mythtv to the include dir in there."

Also note that the linuxtv driver may be a slightly different and newer version than the one shipped with the latest released 2.6 kernel.

My main MythTV system now runs Fedora Core 3 (with a stock 2.6 kernel rather than a RedHat patched one). I didn't notice any problems switching to the 2.6 DVB drivers and as 2.6 also includes Alsa sound drivers it's a couple less things to worry about after each future kernel upgrade.

The Fedora kernels include the DVB drivers. If you build custom kernels Video For Linux and DVB will need to be enabled. Compile the DVB modules you need or all of them if you're not sure. Don't compile this sort of code into the kernel directly even if you have the option. Sometimes you can get round problems by removing and reinserting drivers, avoiding the need for a reboot.

The 2.6 kernel includes Alsa drivers and deprecates the OSS ones. I haven't enabled the Alsa code in MythTV yet and I haven't noticed any problems with 2.6 Alsa audio drivers in OSS compatible mode.

Firefox Users Read This!

These pages currently see about 200-300Mb of traffic a month. As of November 2004 Firefox is now the most used browser to access this site, taking 38% of traffic overall. For comparison in July 2004 it was only 2.5% so it's easy to see the remendous progress this browser has made this year.

Personally I'm sticking to Mozilla but I thought anyone unfortunately still reading this in Internet Explorer might like to know that they are now officially in the minority.

Useful Links

This is unlikely to become an exhaustive list of places to find DVB information. I'll add sites and resources that I've found useful while setting up my system.

Came across this utility today for dumping out and decoding DVB streams. I haven't tried it yet but it looks useful. FAQ
Answers to frequent questions, mostly about Freeview / DVB-T in the UK
The Metzler Brothers
Useful drivers and utilities including REPLEX for working with DVB streams.

Martin Smith
Last Updated March 2005. Hosted with the nice people at clued up hosting.