MythTV failing recordings and device mappings

After upgrading from FC12 to FC16, I began having some issues with failing recordings. After boot, recordings from certain channels would always fail (in this case channels using DVB CAM).

My setup is this:

• “ST STV0297 DVB-C” -> Free channels
• “ST STV0297 DVB-C” + CAM -> Pay channels
• “Philips TDA10023 DVB-C” -> Free channels

I had mythtv configured that my CAM card is on /dev/dvb/adapter2/frontend0.

What I eventually figured out was that after the upgrade from FC12->FC16, my DVB CAM card was no longer always being assigned the above adapter2 mapping. Instead, the hardware used for “adapter2” kept on changing each boot:

Jul 21 14:38:13 localhost kernel: [    7.187973] DVB: registering adapter 2 frontend 0 (ST STV0297 DVB-C)…
Jul 21 19:47:43 localhost kernel: [    8.625730] DVB: registering adapter 2 frontend 0 (ST STV0297 DVB-C)…
Jul 21 19:52:49 localhost kernel: [    8.572348] DVB: registering adapter 2 frontend 0 (Philips TDA10023 DVB-C)…
Jul 21 21:03:04 localhost kernel: [    7.606219] DVB: registering adapter 2 frontend 0 (Philips TDA10023 DVB-C)…

Still, mythtv assumed that adapter 2 had the CAM. This of course led to a situation where mythtv couldn’t record, because it didn’t have the hardware to decode the channel on the specified adapter. This was evident when watching live TV, the “LMSc” never changed to “LMSC”. The capital C means it’s successfully decoding.

So, basically, you need to fix this by manually assigning the device mappings. After doing that, I now have symlinks like these:

/dev/dvb/adapter-ttfree/frontend0 -> ../adapter0/frontend0
/dev/dvb/adapter-ttcam/frontend0 -> ../adapter2/frontend0
…

The instructions for setting up permanent device mappings can be found here: http://www.mythtv.org/wiki/Device_Filenames_and_udev

This is basically the file I ended up with:

/etc/udev/rules.d/55-dvb.rules
SUBSYSTEM==”dvb”, ATTRS{product}==”anysee*”, PROGRAM=”/bin/sh -c ‘K=%k; K=$${K#dvb}; printf dvb/adapter-anysee/%%s $${K#*.}'”, SYMLINK+=”%c”
SUBSYSTEM==”dvb”, ATTRS{vendor}==”0x1131″, KERNELS==”0000:07:01.0″, PROGRAM=”/bin/sh -c ‘K=%k; K=$${K#dvb}; printf dvb/adapter-ttfree/%%s $${K#*.}'”, SYMLINK+=”%c”
SUBSYSTEM==”dvb”, ATTRS{vendor}==”0x1131″, KERNELS==”0000:08:01.0″, PROGRAM=”/bin/sh -c ‘K=%k; K=$${K#dvb}; printf dvb/adapter-ttcam/%%s $${K#*.}'”, SYMLINK+=”%c”

Note, the file is hardware specified, so you need to create your own according to the instructions on the above page. Next reboot, you should have the device mapping symlinks setup correctly.

Now you just need to configure mythtv to use these symlinks instead of referring to adapterX directly. Personally, I deleted all mythtv capture card configuration and re-did it. I don’t think that’s strictly needed, but I just wanted to clean up my configuration a bit at the same time.