MythTV a Second Look

MythTV a Second Look by Colin McGregor

The following is an updated version of an article I wrote for the Linux Journal website back in 2005. A number of things have changed since that 2005 article was written, and anyone wanting to get an idea as to how things have evolved should have a look at http://www.linuxjournal.com/article/8658

Cable TV companies, satellite TV companies and independent firms like TiVo are all pushing personal video recorders (PVRs), boxes that record TV shows on to a hard drive. MythTV is an open source option for doing what the commercial boxes do and more. As with the commercial boxes you have the ability to select the TV shows you want to record by using an on-screen menu, pointing and clicking your way way through a schedule by show name or time.

Unlike the commercial boxes in a MythTV box you can build as much storage into a MythTV box as the Linux kernel and/or your budget allows. MythTV supports multiple tuner cards, so you can record from as many channels simultaneously as your hardware allows. With multiple tuner cards you can simultaneously record TV shows from multiple sources, like over the air antenna and cable. Thanks to the program Miro, MythTV can automatically download video podcasts and present those. With its links to Xmame, MythTV also lets your box act as a video arcade. As with the X Window System, MythTV is set up on a client/server model. While most people set-up the client/server in one box you don't have to, this means you could set up a central TV server in one place feeding video to computers through out a building.

Another feature in MythTV is the ability to auto-skip commercials. MythTV can examine a TV show, attempt to figure out where the commercials are, tag them and then skip over them when you play the show. In practice this system works very well, in my experience over 95% of commercials are correctly tagged. Still, some US comedy show commercial parodies get incorrectly tagged and some commercials on TV channels originating in the European Union get missed. For the errors, you can tell MythTV to present a show, ignoring the tags or you can just fast forward through commercials.

MythTV is somewhat of a hardware pig, in estimating how much recording time you will get out of a hard drive assume about 7.5 GB / hr. for HDTV records and about 2.2 GB/hr., for analog TV. This means it is fortunate that 1+ GB hard drives are inexpensive. Further, if you are thinking of recycling an old computer for MythTV keep in mind that anything slower than a Pentium 4 3.2 GHz will likely be too slow to be usable with HDTV.

For TV tuner cards, the MythTV wiki maintains a list of supported tuner cards. The Hauppauge HVR series of PCI/PCIe cards and the SiliconDust HDHomeRun tuner to Ethernet external boxes are generally very well supported. For channels your cable or satellite provider encrypts you should look at the Hauppauge HD-PVR box that takes the output of the cable or satellite boxes and turns that into a digital stream suitable for MythTV.

While many PC motherboards do include built in video graphics, many have poor support under Linux and/or poor performance, so you may have to go to a separate video card. nVidia-based video cards rule when it it comes to high performance Linux video, with excellent Linux drivers. VDPAU offers video decoding on the card and is a feature that showed up starting with the nVidia GeForce 8200 series cards, and most subsequent cards. VDPAU is supported by MythTV and can significantly improve the performance of a MythTV machine. Other things to look for in a video card is fanless cards, as you would like your MythTV box to be as quiet as possible. One caution, some fanless video cards have heat sinks so large they will block the neighboring PCI/PCIe slot, a potentially major issue for people attempting to set-up a small form factor PC.

Anyone planning to build a MythTV box from scratch should think about cases. Most people will want a PC that blends into the living room / family room / bedroom decor. There only seem to be three firms that pay serious attention to the home theater PC case market, Antec, Silverstone and Thermaltake. All three firms produce some PC cases that could easily be mistaken for high-end audio equipment and could fit into most home situations.

It used to be that setting up a MythTV system was a major pain as you had to first install and configure the programs MythTV depended on, such as the MySQL database and the LIRC infrared remote control program. Now there are three MythTV specific Linux distributions that make setting up / maintaining a typical dedicated MythTV machine fairly painless. The distributions are, LinHES an Arch based installer, Mythbuntu an Ubuntu based installer, and MythDora a Fedora based installer. Which of the three is best can be argued, with the best advice being go with which ever is based on a Linux distribution you are familiar with.

A feature of all good PVRs is the ability to point and click what shows you want to record. This means MythTV needs to somehow know when/where, for example. Doctor Who or Lost Girl will be shown. In the United States or Canada, most MythTV users set up an account with Schedules Direct, a not for profit firm that provides TV listing data for open source software projects, for a modest yearly fee.

For those outside the US and Canada, most people use the XMLTV program. XMLTV as of this writing, can grab TV listings for Australia, Argentina, Belgium, Brazil, Britain, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Hungary, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Reunion Island (France), Romania, Slovenia, South Africa, Spain, Sweden and Switzerland from local Web sites. XMLTV then turns the listings into a format that MythTV is happy with.

As an alternative to XMLTV or Schedules Direct, MythTV can use EIT (Event Information Table), schedule information that many digital broadcasters are transmitting with their programming. The quality and quantity of data available depends on the broadcaster, so varies a great deal, but in some cases can be a replacement for Schedules Direct or XMLTV.

To support the ability to use a TV-style remote you will need a remote control / detector supported by the Linux Infrared Remote Control (LIRC) software. While infrared is in the name, the LIRC software does support a few radio (RF) based remote controls.

There is a MythTV users mailing list that is useful, but at around 100 messages a day, is high volume. The list is also international so some issues discussed will not apply to your part of the world. Other sources of help are the major search engines such as Google and Yahoo. A fairly safe bet is that someone else has had the same problem you have had and it is likely a solution has already been posted on-line somewhere.

There are possible legal issues with two MythTV plugins, add on programs MythDVD and MythGame.
In order to be able to watch the DVDs with MythDVD you need a program that can deal with the Content Scrambling System, or CSS. CSS is the encryption system used on most DVDs to supposedly prevent DVD piracy. Some movie studios have sued to keep CSS software or even links to CSS off the Internet. Still, some modest effort with the major search engines will turn up explanations on how to get CSS software and how to make it work with MythTV.

Other legal issues can come up with MythGame, which uses Xmame to allow you to play old video arcade games. Xmame mimics the hardware of old machines and can support over 6,000 games. After all, a quad core 2GHz, 64-bit PC has no trouble mimicking 35-year-old, 1MHz, 8-bit video game hardware. The old video game software for Xmame can be an issue, though, as all of it still is under copyright. Thus, there can be issues running it under Linux. Copyright holders for eleven Exidy video games plus three other games, Alien Arena, Gridlee and Robbie Roto, have given their permission for non-commercial use of their games. Before you can legally play the thousands of other old games available, you need to get the ROMs that originally were shipped with the game. Once you have an original set of, say, Pac Man, or Donkey Kong ROMs, you can in most jurisdictions legally make a backup copy to your PC and then run the backup copy on your PC.

Colin McGregor (colin@mcgregor.org) does consulting side and has served as President of the Toronto Free-Net. He also moderates the Unix Unanimous user group and is occasional guest speaker at the
Greater Toronto Area Linux User Group meetings.