0.18 – Usable!

So I spent a little bit of time playing with myth last night.

I’m now using Matt Zimmerman’s debs to get around compiling things.

I used Debian’s module-assistant to compile the nVidia kernel modules that I need for TV-out, a wonderful tool that does all the tricky stuff for you.

There’s even a recent enough release of lirc in Debian now that supports kernel events interface; although, setting it up was a nightmare, much harder than last time. The configuration file format seems to have changed, but there were no parsing errors, just silent failure. And the walk-through setup wizard output incorrect configuration information…

The web interface needed a tiny patch to work, a call to intval() around the port parameter passed to the fsockconnect call that connects to the backend, no idea what’s going on there.

I also had to hack the database a fair bit, it had metadata about hundreds of recordings made last year that had long been deleted from the filesystem, listing the recorded programs was taking an age as it attempts to get a keyframe of each and every missing recording.

The new version has much better DVB support than previous versions, though the channel input dialog is a big finicky (add a transport for each station frequency, then do a scan on all existing transports). Channel Seven doesn’t seem to play ball here, but I haven’t tried recording anything yet.

As for playback, colours look off, I’m not sure why yet. Panning and scrolling look horrible, not enough grunt maybe, I’m yet to look at the load of the box during playback. The speedup on playback option rocks, Kevin Rudd almost speaks as quickly as a normal person using it.

Channel Icons

I’ve now extended my D1 parser to grab channel icons. There’s a winding path to follow to get mythtv to use channel icons, I think it’s to do with non .au networks having multiple channels per network. Instead of just using the icon element in the channel description, there’s an icon mapping file that needs to be imported into mythtv. My parser generates that file, the user imports it, then mythtv takes care of the rest.

Oh well, it works.

D1 Parser

The folks at D1 make commercial myth boxes, they’ve got program data up that I wrote a tv_grab_d1 script for use with myth.

I’m gonna wash that XSLT right outa my hair..

TV cable splitter

Finally got around to buying a two dollar cable splitter so it’s not necessary to do any cable switching; there doesn’t seem to be any interference between PC and TV.

tv_grab_dvb

One of the data streams that can be pumped out in parallel to the TV signal is an electronic program guide (epg). tv_grab_dvb parses this information and outputs an XMLTV format file for use with myth.

The program worked just fine, but it seems that the Queensland broadcasters only transmit a program guide that’s a few hours ahead, rather than a seven guide day that Sydney siders get.

Mythtv on Debian guide.

Now that I’m getting close to having a working mythtv setup, it behoves me to write up my experiences in the hope that it helps someone else out there. My guide is a work in progress, but hopefully there’s that useful bit of information to save people scratching their heads for hours on end.

XVMC

Without actually knowing what XVMC actually is, XVMC is the X11 interface to MPEG playback hardware on modern video cards. NVidia is the only brand of cards that people talk about using it with, I’m not sure if that’s just because NVidia are the only people to write drivers for it or what.

I finally got around to getting xvmc working with mythtv, and on my woefully underpowered system it makes all the difference in the world: live TV is stutter free (the front end no longer pauses to buffer input) and the CPU usage is down to around 40% when displaying a 460×480 picture.

There was a fair bit of stuffing around involved as I eventually discovered that XVMC and TwinView (an NVidia configuration option that allows the Monitor and TV to display the same image) don’t work together, only one display can use the MPEG hardware at one time. The NVidia documentation came to the rescue again, however, and walked me through setting up the TV and Monitor to be separate screens on the same display, such that the TV is :0.0 and the Monitor is :0.1, which lets the myth frontend use the MPEG hardware.

I also setup the NVidia AGP driver, it seems to provide some marginal improvements.

All in all, the current setup is almost usable. The picture on the TV is not full sized, or particularly smoothly rendered.

Bugs, patches and ..more bugs

Filed Debian bug 241449 initial scan data not packaged.

Sent some Brisbane data for the dvb utility scan upstream.

My current problem is getting the myth front end to use the ALSA sound driver, configuring mythfrontend using ALSA:hw:0,0 just doesn’t work, the gui just ignores that device string, with no reason.

Sound and remote success

All I’d done was plug in the wrong value for the sound ID, how silly of me.

The remote setup is *finally* there. Unfortunately I have to use a pre release version of lirc for it to work, but oh well. I still had to stuff around with the lircd.conf to add scan codes for half my remote’s buttons, and then muck around with Mythtv’s lircrc file to map the keys to something sensible, but now that I know how to do it, it’s not so bad.

Linux TV 1.1.1 and some Mythtv success

I’ve upgraded to the 1.1.1 dvb drivers, if anything, it feels slower :/

On the other hand, after a *lot* of futzing around with the new mythtv channel picker I finally was able to watch some TV (sans sound) through Myth. Why oh why is it so darn hard to import tzap’s channels.conf file into Mythtv, surely someone has wanted to do that before? There’s very little docco out there on either configuration format.

At least I’m learning, through bitter experience, all those things which make a program easier to use. For example, if you spit out a critical error saying such and such isn’t configured, you damn well better mention such and such in the documentation.