Fettling Myth - New Freeview channel

Prompted by a post on the myth users list, I thought I'd have a stab a manually adding two new channels to my Myth system. It turn out to be trickier than I expeected.

The post covered adding the new channels to the xmltv configuration, but not Myth. As it turns out, it is not strictly necessary to alter xmltv at all, but it is better to do so.

The mods to xmltv expend the set of channels that it is aware of, allowing it to output data using sensible id's, instead of generating default id's. The 'channel_ids' file of xmltv essentially contains a mapping from the channel identity used by the source on the web, to a more meaningful version. The data is still accessible without the mapping, but it is then necessary to use the default, which is Cxxxx.radiotime.com.

The integration between myth and xmltv involves separate definition file for each myth input source. These files contain a list of the channels that are of interest in each case. So it was also necessary to add the xmltv id's of the new channels to the relevant input source file.

Once the mods to xmltv and the input source definition were made, running mythfilldatabase created two new channels in myth.

At this stage, I realised I had probably go about this in the wrong way, since the new myth channel records were missing a number of key fields. To fix this I shut down mythbackend, and ran dvbscan to get the latest dvb on-air channel data, and used this to fill in the serviceid for the new channels.

I would expect that Myth could do this automatically, but it was late and I did not feel like taking the risk.

When changed my ISP, outbound e-mail stopped working, which I expected, for reasons that I did not.

I could have sworn that all my outgoing e-mail was being relayed via a server at my old ISP. This turns out not to have been that case. Specifically, I could find no trace of any reference to any ISP smtp server.

I have to assume that the old ISP was not stopping my system delivering e-mail directly. The new ISP quite definitely does.

So, I added an entry to my /etc/postfix/main.cf file as per http://nlug.org/mail/nlug__2004_01/0177.html. This re-enabled my outbound e-mail.

Getting DVGRAB to just work

Despite previous attempt, I could not get DVGRAB to work unless I typed some magic words. Turns out I was casting the wrong spell.

The machine concerned runs FC3, and connecting a camcorder would create a entry at /dev/raw/raw1394. DVGRAB looks for /dev/raw1394, so I needed a fix. I had found a post somewhere that suggested an alias based approach, but this would not stick, needing to be invoked after each reboot.

I had figured out that this was all connected with UDEV, and google took me to http://www.linux1394.org/faq.php#udev, which I tried, but to no avail.

When I gave up the trial and error approach, I discovered that I was ever so close. My FC3 setup has the UDEV rules in /etc/udev/rules.d, so I moved the file I had placed /etc/udev/10-ieee1394.rules into rules.d and hey-presto, it worked.

Mystery solved : why MythFillDatabase does not just work

If you keep plugging away, you get the answer in the end. Ever since I rebuilt my first myth box, the option to have mythbackend run mythfilldatabase did not work. For ages I just lived with it, running MFDB manually. Finally I got fed up with that, and we were going away for a couple of weeks, so I trawled around and found a fix.

The fix revolved around configuring mythbackend to invokde mfdb with an explict reference o the grabber config file. Being an utter newcomer to linux et-all, I had trouble but I got it working.

When I cloned this set-up and added a second video source to the clone, it all went pear shaped again. The fix that I had applied made no provision for multiple sources, so I was back where I started; The second source would not download. I should have exepcted this.

Anyway, I stopped stabbing in the dark and actually looked at the problem. Turns out that my grabber config files were in the wrong place all along. Mythbackend runs under root, but it's home directory is '/' not '/root'. I don't fully understand why this is, but I am kind of new to all this.

So... I created a soft-link to /root/.mythtv and called it /.mythtv . I figure that this is less likely to confuse me later on. It also fits the pattern where I already had links the make the grabber config files appear in /root/.mythtv when they are actually in /home/mythtv/.mythtv .