The ongoing MythTV saga continues

I have good news, bad news, and worse news. The good news is that I managed to get MythTV working well enough that it now plays standard definition channels better than the cable box alone, even though it's getting its signal from the cable output of the cable box. I get this benefit because MythTV allows me to tweak various parameters that you can't change on the cable box.

The bad news is that high definition channels still look worse through MythTV than they do if I watch then directly from the cable box. I don't expect to solve this problem. The cable box may be able to handle HDTV itself, but it outputs a digital signal in 480p, which is basically standard definition. The fact that I have two HDTV-capable tuner cards does me little good.

Here's the worse news. I had to learn way too much to get this far.

I now know the difference between ATSC and NTSC, what vertical blanking is, how to use things like overscan percentages to adjust a picture, and much more. I still haven't tried to set up a remote and IR blaster, so there's a lot of research left to be done. Aside from a little more tweaking, this will be my final step -- to add a remote control that sends a signal to an IR blaster in order to change channels on the cable box.

I admit that I find everything I have learned interesting, and I will enjoy writing it up as a Linux Journal article when I'm done taking this project to a point where I'm satisfied with the results. But I don't think I should have had to become so familiar with everything from driver firmware to the way television signals are formatted in order to get satisfactory results. It was never my goal to learn any of this.

Bad simile

It's unrealistic to make a one-for-one comparison to buying a car. This is, after all, a PC, and it requires additional hardware like a tuner card just to get started. Even a Windows installation of similar software would require you to install a driver, reboot, and then step through a wizard setup program to get everything working. Of course, there is Windows Media Center Edition. I've heard that it is relatively trivial to install a tuner card and get Windows MCE to behave as a PVR, but I can't confirm or deny it from personal experience.

Regardless, I am tempted to compare it to buying and driving a car if only because I have absolutely no interest in learning how a piston engine works. I'd rather walk than learn about piston engine internals. It is pure coincidence that I found the technology interesting in the case of MythTV. There's no reason why anyone who isn't interested should have to know these things just to turn a Linux box into a decent PVR.

No way out

One cannot solve this problem by writing a good How-To, either. You need to know too many details about your own equipment in order to get optimal results. The MythTV software doesn't make any attempt to detect hardware, television signals, configuration details. It doesn't walk you through the process of discovering these details and it doesn't give you any advice on what to do with the information you glean on your own. It even puts some configuration options in unusually awkward places.

For example, you can't adjust the contrast or brightness from the MythTV front end software. You have to run the MythTV setup program to do that, and you have to do it channel-by-channel. Not only is this inconvenient, you can't view how your settings will affect the quality of the picture until you exit the setup program and start the front end again. Maybe you can run the two programs simultaneously, but it was more trouble than it was worth to find out. I only want MythTV to receive channel 3. That's the output of my cable box. But I pity the poor fool who needs to adjust things like contrast, brightness, color and hue for multiple channels.

MythTV is still excellent

Some of MythTV is simply brilliant. I love the fact that MythTV is a client/server application. You can connect a back-end server to the cable box and watch TV with the front-end software on any other computer on your network. There's a lot more to like, too, such as the variety of add-ons that make MythTV much more than a PVR. I'm not ready to talk about these plug-ins because I haven't tried them yet. But there's a music player, phone plug-in, browser, picture gallery, speech synthesis (via festival), and more.

I guess I'm simply disappointed that MythTV is like so much other free software. It is built under the assumption that people who use it know (and care) about the technical details that the authors know (and care) about. In short, it's by geeks, for geeks. I confess, I'm a geek, and many of you are geeks, too, so I hope you enjoy the How-To article when I get to it. But I still have compassion for the non-geek population, and I wish more developers had the same.

To be continued...


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Well its early yet

philc's picture

The world of TV is rapidly changing both from the broadcasters/cable end and the receiver end. The funky details are complex and not easy to understand. Here in the Boston MA USA area, we have broadcast NTSC (old style TV), ATSC (digital TV including HD), Cable both analog and digital, and Satalite TV. For example, given a TV card what is the required driver? What does it connect to (antenna, cable)? How do you find the channels you can receive? For example I have an analog tuner card directly connected to the Cable. It tunes analog cable channels very well. I also have a PCHDTV card connected to an antenna for broadcast HD tv, that works great too.

The display end is no less complex with various CRT/LCD displays and TV monitors of various resolutions with component/S video/RF/vga/hdmi connectors. Then there is the graphics card. There are dozens to choose from. Then, of course, there is configuring X properly.

And then there is the sound. Any number of cards work. HD supports Dolby 5.1 sound. Do you want to go there? Whatever you choose get it working first before getting to Mythtv.

None of this is really directly addressed by Mythtv. You are expected to have an up and running system by the time you get to Mythtv.

Mythtv adds the complexity of working with a database, MSQL 4. This in and of itself is a challenge. It also permits working with a remote. However, as before it expects you to get the remote and its driver setup and working before getting to Mythtv.

Today its a real chore to get all of this up and working, before attempting Mythtv. However, with all of this working, its pretty easy to compile/install/configure/run and enjoy Mythtv.

For being a 0.19 project Mythtv is pretty impressive.

Don't blame MythTv for low level device problems.

OpenMedia myPVR MythTV Appliance

Steven Ellis's picture

At OpenMedia have developed a MythTV based appliance for the New Zealand market called myPVR. One of the tricks is to standardise your hardware platform to assure support for customers. Only selected video capture cards and wireless cards will be used to assure compatability.

One difference here in NZ is the reduced choice for consumers. We don't have a lot of channels, and no HDTV. We are already have full support for the new digital network that isn't due to be launched until next year, but at presengt that will only broadcast in SD.


SD vs. HD

Nicholas Petreley's picture

This is the crux of the problem for me. My cable box (Scientific Atlanta 8300HD) receives HD cable and renders it beautifully. It has a built-in PVR, and it records HD very well. Even though it has to scale it down to S-Video, I can even play back PVR-recorded HD content and use the output to record it to DVD. The result is not as crisp as watching the show live, but it's still great.

Unfortunately, there are only 3 outputs of the 8300HD for use with a MythTV box: AVI (composite), S-Video (and audio from the composite), and the cable out (tuned to channel 3). None of these transmite HD. The cable out transmits ATSC at various resolutions, so I should still be able to get decent quality on MythTV, but so far, I can't. I said a while back that I was able to get the quality of SD channels to look better than SD on the cable box, but that isn't consistently true. I'm not sure why it is better one moment and worse the next. But HD content is always much worse -- worse than it looks when I record it via S-Video to a DVD! That doesn't make much sense, does it? If the S-Video is sending good quality video to the DVD recorder, why doesn't it send good quality video to my capture card? Or if it is sending good quality video to the capture card, what am I doing such that it's making the quality worse when it puts it on the TV? I still don't have answers yet.

So if the 8300HD is a PVR and does everything so well, why do I want a MythTV box? Well, I certainly don't need one, but I'm terribly spoiled on the magnificent user interface of my old TiVo, and the 8300HD has a TERRIBLE user interface for scheduling recordings and managing them. That alone wouldn't make me build a MythTV box, but I thought the process of doing so would help me write a good article for Linux Journal, so I figured I'd tackle it.

I'm glad I did, because I learned a lot. Even if I give up on MythTV for my own use, at least I'll have a lot of knowledge to share in the article.

S-Video quality

pbardet's picture

It's true that it's weird that you can't get the same quality out of the S-Video, between the DVD recorder and the capture card. Maybe you have a "bad" capture card. I've never noticed any problems with mine (Hauppauge 250) while capturing Bell ExpressVu sat feed from Svideo. They were as clean as they were on the PVR.

I use the past tense since I switched to Freevo as it handles better my needs and since then I haven't setup yet the video recording. MythTV was like using a sledgehammer to smash a fly. I was not using half the features/plugins of MythTV, neither did I like the MySQL needs.

SA 8300HD does FireWire

Rick's picture

You didn't mention firewire on the 8300HD, which does exist, but may or may not be enabled. I believe by law, your cable provider must enable the port if requested. It may take some "talking to the right people", but I know people who have had it done (at least on Cox).

There are also HDMI and component outputs - are there capture/tuner cards capable of receiving either signal for PC that are Linux compatible?

I agree, however, that the 8300HD interface is horrible. I'm looking forward to a howto as I'd love to use MythTV just to archive my DVD's and music to disk so that my kids don't need to (mis)handle DVD's and CD's.


Nicholas Petreley's picture

The firewire ports aren't on my model. There are 8300HDs that have 2 firewire ports on them, but mine doesn't have any. When I get the time, I'll check with the local Time-Warner office to see if they have any 8300HDs with firewire.

Granted that "there would

Anonymous's picture

Granted that "there would always be incurable problems on obscure/cheap hardware," we do need to strike a more usable balance. What's the difference between your specialized, sold-as-a-unit hardware/software combo and a Tivo?

the difference

ms's picture

The difference is that you cannot "tweak" the TiVo's insides.

Look here:
... and here:

Also, TiVo spies on you...

Basic mythtv problems

Anonymous's picture

The current problems with mythtv as I see them are...

lirc is not in the main kernel
canned lirc configs are not available/installed
ivtv is not in the main kernel
mythtv binary package support isn't quite there
"easy" distros don't include kernel mod support by default

required alterations to mysql to get remote frontend support aren't automated. -- This is something that I also see as an architecural issue. The frontend should just talk to the mythd on the backend and not even know about the database.

Most of those major stumbling blocks are pretty simple actually.

My first mythtv install was completely automated by using binaries present in the Debian repositories. Didn't have lirc or ivtv support though.

That kernel module build issue is also a problem for Nvidia binary drivers, ati binary drivers and vmware installs.

MythTv architecture

TexasMythTvUser's picture

I concur with the remarks of Anonymous. The MythTv architecture is strange in that the frontend requires a DB connection to the backend sql server. Also, the only way I was able to get my frontend on one machine talking to the backend was to NFS-mount the stored recordings. I would expect that the backend should stream playback to the frontend. As far as I can tell, it can't do that right now. Or maybe it is time for me to RTFM again. MythTv is powerful, but its configuration is definitely not simple. There are some novel features in the UI, but in general, it looks like one of those UIs designed by programmers/engineers, not by a human factors specialist. That being said, I'm a big fan of linux and MythTv, and use both daily.

MythTV distro

Anonymous's picture

Anyone has test this linux distro