A MythTV Home Media System

Documentation

There is now a single main source of information about MythTV, the Wiki, at www.mythtv.org/wiki. The two primary sources of installation information are the Installation Manual and the Wiki Installation Page. Someone has been doing a great job updating the User's Manual, and I recommend it for information about using your MythTV system once setup.

There is an official mailing list for users of MythTV, which has a searchable archive. There is also searchable archive for the MythTV development mailing list.

There are a growing number of HOWTO documents being written. Here are a select few:

• Status Monitoring
• MythWeb SSH Tunnel
• nVidia MX4000
• DVD to DVD Backup

Other sites describing MythTV installs include:

• The EFF's Most Excellent Guide to Building Your Own PVR
• PVR-250 on Debian (R. Wilson)
• ITX hardware and Debian (Roger Lipscombe)
• Fedora Myth(TV)ology (Jarod Wilson)
• HD DVB-T on Fedora (Jani Talikka)
• PVR-250 on Ubuntu (Christopher Scholz)
• PVR-xx0 on Ubuntu (Daniel Hyams)
• PVR-150 on Ubuntu (Andrew Barbaccia)
• PVR-150 on Ubuntu (Joe Kallo)
• PVR-250 on FreeBSD (Ari Maniatis)
• ITX hardware and Gentoo (magicITX)
• Official Gentoo MythTV Install Guide
• X-Box front end

Email me if you find userful sites that I have missed

Hardware & Operating System

I strongly recommend using hardware encoders. The PVR-150/250/500 series from Hauppauge is a rock solid and cheap solution at this time for analog NTSC (terrestrial broadcast and cable in the US). Using hardware encoders means that you can use older equipment as the video server, and support many tuners.

How many tuners ? The rule of thumb I've developed is that you want at least 1 + N tuners, where N is the number of TV which are simultaneously watched in a home. If PIP is used heavily, this becomes 1 + 2N. You can add additional tuners in thick clients if N is large. This rule minimizes the number of times that a recording has to be cancelled due to a shortage of tuners.

My main home mediaserver is a Pentium III Celeron running at 900MHz (with 256 MBytes of 100MHz SDRAM on an i815 based ATX motherboard), and a 200 GByte Western Digital disk. It has two Hauppauge PVR-250 PCI cards, each providing a cable TV tuner, digitizer and hardware MPEG-2 encoders.

One dedicated remote client (and secondary mediaserver) is an AMD Sempron (K7) 2500 (with 512MB of 133MHz SDRAM) on an MSI KM4M-V mATX motherboard, and a 40 GByte local disk. It uses an nVidia GeForce4 MX4000 based graphics card for NTSC/S-Video video output. It has a single Hauppauge PVR-250 card for video input (and encoding) and does software decoding for display. It works very well, and also performs transcoding and commercial detection for the system with its idle processing power.

I have used several generations of Shuttle computers as MythTV servers/clients. These are compact, powerful little machines which recently have gotten quiet as well! (Shuttle Related Issues)

All mediaservers are running the Debian distribution of the Linux operating system. They are currently running a testing release with a custom 2.6.14 kernel, but the standard 2.6.8 kernel is fine. You will need to use GCC 3.3. While MythTV itself appears to be GCC 4.0 compatible, some of the codecs and support applications that you will want available in MythVideo and transcode do not compile with GCC 4.0 (or 3.4).

If you install a newer system, you can indicate your preference for a system compiler by replacing the gcc and g++ links in /usr/bin with ones to older versions:

sudo apt-get -y install gcc-3.3 g++-3.3
pushd /usr/bin
sudo ln -s gcc-3.3 gcc
sudo ln -s g++-3.3 g++

This is not an ideal situation, as some of the development libraries are provided by Debian and are compiled using the default, newer, compiler. You should probably have apt configured to support pinning, using both the stable and testing packages.

Required Packages

sudo apt-get install unzip mysql-server mysql-client libqt3c102-mt \
    libqt3-mt-dev/stable qt3-dev-tools/stable libqt3c102-mt-mysql \
    freetype2-dev libasound2-dev libxinerama-dev libxxf86vm-dev

sudo apt-get install automake autoconf libtool libtiff4-dev libcdaudio0-dev \
   liboggflac-dev libid3tag0-dev libmad0-dev kdelibs4-dev libdvdread3-dev \
   libgtk-dev lirc lirc-modules-source libxaw6-dev libmagick9-dev \
   libdts-dev libcdparanoia0-dev fftw3-dev libxml-simple-perl libwww-perl

If you are going to use a Debian machine to run a front end, make sure that sound is working correctly. If it isn't, see some of my installation suggestions.

Program Guide

The program quide for MythTV is obtained from Schedules Direct, a non-profit distributor of such information to open source projects. It does cost money, unlike earlier MythTV program guide suppliers, but it is relatively cheap ($15 per six months). You will need to open an account with Schedules Direct --- the username and password will be entered into mythtv-setup for downloading your program guide information (my member ID is wad451 and my password is the ML hardware mailing list).

The guide information needs to be downloaded periodically. This is best left to the MythTV software. There is a check box somewhere in the configuration maze for disabling the automatic download by the master backend server (it was handled by a cron job in older installations), but I recommend against it.

You can check on the status of your subscription from a MythTV top-level menu by selecting Information, then System Status, or using MythWeb (status page, at the bottom).

IVTV

IVTV is the wonderful piece of open source driver software which allows us to use the readily available Hauppauge MPEG compression cards (PVR-150, PVR-250, PVR-350, and PVR-500) with MythTV.

The Debian Way

One approach is to pull the sources from a non-Debian repository, and compile and install them using the module assistant tool. Take a look at the Debian How-To. (Let me know how this approach works for you...)

Manual Installation

You can download the driver source for your kernel (check the download page, currently 0.4.7 for pre-2.6.15 kernels and 0.8.0 for post-2.6.17 kernels) and compile it against your kernel source to produce a driver suitable for your system. This requires that you have either compiled up your local kernel or have the appropriate kernel-headers or kernel-source package for your kernel installed.

wget http://dl.ivtvdriver.org/ivtv/archive/0.4.x/ivtv-0.4.7.tar.gz
tar xfz ivtv-0.4.7.tar.gz
pushd ivtv-0.4.7 ; make

wget http://dl.ivtvdriver.org/ivtv/archive/0.4.x/ivtv-0.8.0.tar.gz
tar xfz ivtv-0.8.0.tar.gz
pushd ivtv-0.8.0 ; make

At this point, you should move some drivers provided with the kernel which conflict with those provided with IVTV:

pushd /lib/modules/`uname -r`/kernel/drivers/media/video/
sudo mv msp3400.ko msp3400.ko.old
sudo mv tuner.ko tuner.ko.old
sudo mv tveeprom.ko tveeprom.ko.old
sudo mv tda9887.ko tda9887.ko.old
popd
sudo make install

NB: Make sure that you are using exactly the same compiler as was used to compile the kernel. If you've upgraded the compiler (even from 3.3.5 to 3.3.6), you will need to recompile the kernel again...

Firmware

The open source drivers do not include the microcode firmware needed operate the encoder/decoder chip. It must be extracted from drivers provided by Hauppauge. You will need to download these drivers (or get them from the CD included with the card), then extract the firmware using a tool provided with the ivtv driver (utils/ivtvfwextract.pl). These instructions must be executed from the ivtv source directory (/opt/mythtv/ivtv-0.4.3/ in this installation).

wget ftp://ftp.shspvr.com/download/wintv-pvr_150-500/inf/pvr_2.0.24.23035.zip
unzip pvr_2.0.24.23035.zip
sudo cp HcwMakoA.ROM /usr/lib/hotplug/firmware/v4l-cx25840.fw
sudo cp HcwFalcn.rom /usr/lib/hotplug/firmware/v4l-cx2341x-enc.fw
wget ftp://ftp.shspvr.com/download/wintv-pvr_250-350/inf/pvr_1.18.21.22301_inf.zip 
sudo utils/ivtvfwextract.pl pvr_1.18.21.22301_inf.zip
sudo rm /lib/modules/ivtv-fw-enc.bin
sudo mv /lib/modules/ivtv-fw-dec.bin /usr/lib/hotplug/firmware/v4l-cx2341x-dec.fw
sudo cp v4l-cx2341x-init.mpg /usr/lib/hotplug/firmware

This will place the extracted firmware in the location where the current version of the ivtv driver expects to find it (/usr/lib/hotplug/firmware/). Versions earlier than 0.40 of ivtv store the firmware in a different location (/lib/modules/) and use different filenames than earlier versions.

Testing

You can test the drivers by simply typing:

cat /dev/video0 > scratch_video.mpg

and stopping it with ^C after a while. There should be roughly 256 to 512 KBytes of data in scratch_video.mpg for each second that cat was running. For a better test, type the following to set capture parameters (test_ioctl is in the utils/ subdirectory of ivtv) :

/usr/bin/test_ioctl -u 0x3000
/usr/bin/test_ioctl -p 4
/usr/bin/test_ioctl -f width=720,height=480     

Now cat some data from /dev/video0 and you should be able to watch it using MPlayer.

Loading at Startup

This section is no longer needed, due to more intelligent /dev systems in newer kernels.

You will need to establish a relationship between the driver module and the /dev filesystem entry. This is done by adding this file to /etc/modutils and running update-modules. The drivers are loaded by calling this script, which should be placed in /etc/init.d/ivtv, and links to it placed in the appropriate runlevel directories (/etc/rc3.d).

Getting Composite/S-Video Out

While VGA output from your MythTV clients is fine if you have a newer flat panel TV, composite or S-video output allows you to keep using your old TV, and dump videos to VCR (although at current hard drive prices, a two-hour movie encoded with MPEG2 at high quality (640x480,4Mb/s) costs slightly more than a dollar to store, beating VHS tapes in price !)

If using a graphics card with an nVidia chip, simply follow the directions on their web site to get configure the main display for NTSC. My X config file is an example.

Another approach if using an nVidia system is the nVidia TV Out software project.

Automatically Starting the Backend

The MythTV backend should be started automatically when a mediaserver (or client/slave server) is turned on. This is done with a startup script. On a debian system, this script should be placed in /etc/init.d/mythtvbackend, and links to it placed in the appropriate runlevel directories (/etc/rc3.d on my systems --- I like to keep runlevel two as an TTY interface, server-free, maintenance level, with runlevel three being the normal one.) ).

Host specific definitions may be placed in /etc/default/mythtv. See the startup script for details.

You can easily manually start/stop the backend using the script (which must be run as root.) The options to the script are:

start

Starts the MythTV back-end server running.

stop

Stops the MythTV back-end server.

restart

Stops, then restarts the MythTV back-end server.

status

Reports the status of the MythTV back-end server.

sudo cp -r ~/.mythtv ~root/

2005-08-17 22:02:26.930 Unable to connect to database!
2005-08-17 22:02:26.931 Driver error was [1/2002]:
QMYSQL3: Unable to connect
Database error was:
Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
2005-08-17 22:02:26.932 Failed to init MythContext, exiting.

faad2

The Freeware Advanced Audio Decoder and Coder libraries are needed for FFmpeg (hence transcode) to support MP4. Get them from http://www.audiocoding.com.

faad2 requires some work to get it to compile, due to confusing errors caused by it being in DOS text file format. I suggest:

wget http://umn.dl.sourceforge.net/sourceforge/faac/faad2-2.0.zip
unzip faad2-2.0.zip; pushd faad2
for i in `find . -type f`; do mv $i $i~; tr -d '\r' < $i~  > $i; rm $i~; done

At this point, remove the build commands for an rpm out of faad2/Makefile.am (or fetch the example). Then configure and build the library as shown below. (BTW, this is a very broken way to use the automake and autoconf tools. End users shouldn't have to install them !)

wget http://watlington.homelinux.org:8000/wad/mythtv/Makefile.am.faad2-2.0.txt
mv Makefile.am.faad2-2.0.txt Makefile.am
aclocal -I .
autoheader
libtoolize --automake --copy
automake --add-missing --copy
autoconf
./configure --with-mp4v2
make
sudo make install

Ignore any errors from automake about source file 'foo.h' is in subdirectory. (See Davesource for another example compilation, including xmms, but note that his DOS format fix doesn't work.)

If you are building mythmusic, you will need to fix a problem with the faad2 installer:

sudo cp faad2/common/mp4ff/mp4ff_int_types.h /usr/local/include/

faac

faac has the same problem with DOS text file format, but since it doesn't generate actual errors upon compilation, it is handled by the codec install script.

You can manually install, unpack and compile it using:

wget http://umn.dl.sourceforge.net/sourceforge/faac/faac-1.24.zip
unzip faac-1.24.zip; pushd faac
for i in `find . -type f`; do mv $i $i~; tr -d '\r' < $i~  > $i; rm $i~; done
chmod a+x bootstrap; ./bootstrap
./configure
make
sudo make install

Theora

Transcode supports the Theora video codecs. You might want to download and install libtheora :

wget http://downloads.xiph.org/releases/theora/libtheora-1.0alpha5.tar.bz2
tar xfj libtheora-1.0alpha5.tar.bz2
pushd libtheora-1.0alpha5
./configure
make
sudo make install

Xvid

This is an open source MPEG4 Simple Video profile codec which I use for almost all video. It provides good results (in two-pass mode) at bitrates of 700 - 1400 kbits/sec.

Install and compile it using the Debian model:

wget http://downloads.xvid.org/downloads/xvidcore-1.1.0-beta2.tar.bz2
tar xfj xvidcore-1.1.0-beta2.tar.bz2
pushd xvidcore-1.1.0-beta2
dpkg-buildpackage -rfakeroot
sudo dpkg -i ../libxvidcore4_1.1.0-0beta2_i386.deb
sudo dpkg -i ../libxvidcore4-dev_1.1.0-0beta2_i386.deb

Unless you've done this before, you will probably need to install the following Debian packages:

sudo apt-get install debhelper fakeroot nasm

NOTE: (2/23/06) If you are using GCC 4.0 as your default compiler, you need to use the .final version of this library. Unfortunately, it doesn't include the debian build directory. You can copy the debian directory from a beta release, making sure to add an entry in the changelog reflecting the different version (example new changelog).

Here's a kludgy script for doing the aforementioned:

wget http://downloads.xvid.org/downloads/xvidcore-1.1.0-beta2.tar.bz2
wget http://downloads.xvid.org/downloads/xvidcore-1.1.0.tar.bz2
tar xfj xvidcore-1.1.0-beta2.tar.bz2
tar xfj xvidcore-1.1.0.tar.bz2
pushd xvidcore-1.1.0
cp -r ../xvidcore-1.1.0-beta2/debian .
wget http://watlington.homelinux.org:8000/wad/mythtv/xvidcore_changelog_1.1.0.txt
mv xvidcore_changelog_1.1.0.txt debian/changelog
dpkg-buildpackage -rfakeroot
sudo dpkg -i ../libxvidcore4_1.1.0-1_i386.deb
sudo dpkg -i ../libxvidcore4-dev_1.1.0-1_i386.deb

FFMpeg

There are many ways of obtaining the FFmpeg libraries, such as mplayer, or directly from CVS. One reasonable approach is to download them from Sourceforge:

wget http://umn.dl.sourceforge.net/sourceforge/ffmpeg/ffmpeg-0.4.9-pre1.tar.gz

After configuring it, make sure to check for errors ! You will need to manually install the libavcodec library, it is not installed by the top level makefile. Configure, compile, and install FFmpeg with commands like:

./configure --enable-shared --enable-pthreads \
  --enable-libvorbis --enable-libogg --enable-libtheora \
  --enable-libmp3lame --enable-libfaac --enable-libfaad --enable-gpl

for the latest version checked out from subversion, or

./configure --enable-shared --enable-pthreads \
            --enable-vorbis --enable-mp3lame \
            --enable-faac --enable-faad --enable-gpl

for version 0.4.9pre1. In both cases, follow with:

make
sudo make install
pushd libavcodec; sudo make install
pushd ../libavformat; sudo make install

libmpeg2

Download the latest tarball for mpeg2dec, and install it using the usual ./configure, make, and sudo make install routine. It installs libmpeg2 as a side effect.

Note: This is probably a good time to point out that some of the software packages being installed do not properly install themselves for the debian default pkg-config installation. Copy the .pc files for libao (ao.pc) and libmpeg2 (libmpeg2*.pc) from /usr/local/lib/pkgconfig to /usr/lib/pkgconfig to correct the problem.

Recent versions of transcode

A recent version of transcode (1.0.2) has problems compiling against the CVS version of FFMpeg. This is due to it needing the pkg-config information but being unable to find it as transcode uses obsolete package names and version defines. Copy libavformat.pc into FFMpeg.pc (adding -lavutil to the libraries), and libmpeg2.pc into mpeg2dec.pc. You will also need to add:

#define FFMPEG_VERSION "0.4.9pre1 build xx.xx.xx"

to ffmpeg/avcodec.h

LibquickTime

This library provides support for the quicktime format, using a number of codecs which we have already compiled up !

You will need to make sure you have the development version of the libxaw package (libxaw6-dev) installed.

wget http://umn.dl.sourceforge.net/sourceforge/libquicktime/libquicktime-0.9.10.tar.gz
tar xfz libquicktime-0.9.10.tar.gz; pushd libquicktime-0.9.10
./configure
make
sudo make install

I tried and tried to get libquicktime to recognize the libavcodec installation, and haven't succeeded yet. I got closest by adding this file as /usr/lib/pkgconfig/avcodec_acl.pc.

In order for other software to auto-detect the libquicktime installation in some installations, it was necessary to copy the pkgconfig configuration:

sudo cp /usr/local/lib/pkgconfig/libquicktime.pc /usr/lib/pkgconfig/

Ogle

Ogle is a standalone open source DVD reader, which includes support for interpreting the DVD menus ! What we really need here is the dvdread library, but we might as well pull down Ogle, it comes from the same folks. Since we are running Debian, we can directly install it:

sudo apt-get install ogle-mmx libdvdread3-dev

Make sure that you and mythtv (and anyone else you like) is a member of the cdrom group (edit /etc/group). You will have to exit and start a new shell (terminal window) for the changes to /etc/group to take effect.

If you aren't running udev, you will have to change the group on your DVD-ROM device (if connected using IDE, it will be something like /dev/hdc, or /dev/hdb) to cdrom. You will also need to manually make a symlink between /dev/dvd and the real device:

sudo chgrp cdrom /dev/hdc
sudo ln -s /dev/hdc /dev/dvd

You might want to install and run regionset to make sure that your region has been set. If it hasn't, the DVD library will fail.

sudo apt-get install regionset
regionset

You can test that Ogle (and your DVD ROM subsystem) is working by inserting a DVD into your drive and running it:

ogle

Finally, you will need to configure each frontend to use Ogle as its DVD player. This is done from within mythfrontend.

MPlayer

MPlayer is the original movie player for Linux. Due to its ignoring any intellectual property claims on codecs it cannot be distributed by the Debian organization. While precompiled versions exist for Debian, I recommend downloading and compiling the latest source:

wget ftp://ftp5.mplayerhq.hu/MPlayer/releases/MPlayer-1.0rc1.tar.bz2
tar xfj MPlayer-1.0rc1.tar.bz2; pushd MPlayer-1.0rc1
./configure
make; sudo make install

MPlayer's configuration script is pretty good at figuring out what you have already installed and using it. You will, however, want to download two additional software packages: some binary Windows codecs (only useful on x86 platforms, for oddball Windows-only movie formats):

wget ftp://ftp5.mplayerhq.hu/MPlayer/releases/codecs/essential-20061022.tar.bz2
pushd /usr/local/lib/
sudo tar xfj /opt/mythtv/essential-20061022.tar.bz2
sudo mv essential-20061022 codecs

and the onscreen fonts used (you can choose a size different than the 18pt one selected here):

wget http://ftp5.mplayerhq.hu/mplayer/releases/fonts/font-arial-iso-8859-1.tar.bz2
tar xfj font-arial-iso-8859-1.tar.bz2
sudo mkdir -p /usr/local/share/mplayer/font
sudo cp -r font-arial-iso-8859-1/font-arial-18-iso-8859-1 /usr/local/share/mplayer/font

If upgrading from an earlier version of MPlayer, be aware that the font format has changed and you will need to download new ones.

Skins for the GUI are now available, if you use MPlayer outside of MythTV.

RTC

If you are getting an warning message when you run MPlayer along the lines of "Failed to open /dev/rtc: No such file or directory", then you need to check the Linux Real-Time Clock kernel module. This is not loaded automatically, if not compiled directly into the kernel, requiring you to add it to /etc/modules.

Once you do have the RTC module loading, MPlayer might respond with an error message like, "Linux RTC init error in ioctl (rtc_irqp_set 1024): Permission denied". You can fix this by adding a file containing the following command to /etc/init.d, and linking to it from /etc/rcS.d.

echo 1024 > /proc/sys/dev/rtc/max-user-freq

or

wget http://watlington.homelinux.org:8000/wad/mythtv/rtc
sudo mv rtc /etc/init.d/rtc
sudo chmod a+x /etc/init.d/rtc
pushd /etc/rcS.d
sudo ln -s ../init.d/rtc S56rtc

MythVideo

MythVideo is a must-have, due to MythTV's native inability to play video recorded elsewhere (in its designer's defense, this also makes it much, much easier to install !). MythVideo simply hands over the playback of the video file to a helper application such as MPlayer or Xine. If you've succesfully run the codec install script, MythVideo should just work, using MPlayer.

The best documentation for MythVideo seems to be the README file accompanying the source code.

You will need to create directories in which to store your movies and associated metadata (images and subtitles). Unfortunately, the metadata must be stored separately to avoid MythVideo assuming that it is a video file. I use /storage/library for the movies and /storage/movieposters and /storage/subtitles for the metatdata. The first two of these directories need to be specified in the MythVideo management interface.

Note that the helper application (MPlayer or Xine) must be separately configured to use an IR remote. This is already handled by the forementioned lircd configuration files.

If you have trouble fetching information from IMDB, make sure that you have the following libraries installed:

sudo apt-get install libxml-simple-perl libwww-perl

A frequent problem (40% of our DVDs) is the lack of a movie poster on IMDB. My work-around is to look up the DVD on Amazon, save the larger version of the DVD cover image and crop it to produce a "movie poster".

Subtitles are handled by specifying a complete command line to be executed in the "Player commands" parameter (this is a pain!) For example:

mplayer -zoom -fs -vobsub /storage/subtitles/Blue /storage/library/Drama/Blue.avi

MythGame

MythGame is a front-end for MAME, which includes simulators for both a large number of arcade games and some Ninetendo games. You have to install the MAME software, then obtain the ROMs from other locations and install them yourself.

Still working on getting this one working.

MythMusic

Myth Transcode Daemon

As of version 0.20, the Transcode Daemon is no longer a separate application.

The Myth Transcode Daemon (mtd) is used by a number of MythTV modules. As its name implies, it does conversions from one format to another. It is also used by MythDVD to rip the DVD.

You have already compiled up the daemon, but you need to test it and set it up to automatically start on machines hosting either a backend or frontend server. Try running it manually:

mtd -n

It should respond with some information, including a line like:

<time>: mtd is listening on port 2442

Once you get it to succesfully run manually, you should install a script in /etc/init.d, such as mythtranscode. and place links to it in the appropriate runlevel directories (/etc/rc3.d on my systems). You must make sure that the user the daemon runs as has a valid MythTV configuration

The Myth Transcode Daemon places it's log file (mtd.log) in the directory you specify for temporary storage of DVD files while they are being transcoded. (I tend to use /storage/dvdbuffer.)

Maintenance

OK. You've finally got everything that you want up and running, and configured to your liking. Unfortunately, Murphy's law has a way of intervening, identifying the components most critical to the operation of your finely tuned system and causing them to go "poof". How can you prepare for some of these eventualities ?

Disk Full ?

You might want to occasionally check to see if any server disk partitions are filling up (use the df command). Experience has shown, however, that the most common method of failure is a user configuration error which slowly fills up the main disk storage with shows which cannot be deleted, which then rapidly fills the partition containing /var with error messages about said disk full issue making the system unusable. The solution is to shut down mythtv, clean out the log files and delete one or two recordings. Then restart mythtv. It should run fine. Now go in and mark more shows (both recorded and yet-to-be recorded) as allowing auto-expire.

Database Backup

The User Manual has a section on periodic maintenance, where they mainly discuss how to back up the crucial information in your MythTV system: the SQL database. They don't discuss how to discard the 95% of this database which is useless (the guide info for upcoming weeks), but the remaining 5% is useful. Note that this doesn't do anything about saving the media files referenced by the database. It just maintains a lot of system state and your log of recorded shows for eliminating duplicates, etc.

The suggestion is to run a cron job (see my script) which periodically makes a backup copy of the SQL database and copies it to a remote server (rsync server, in my case).

The database could be reconstructed using the following commands: (mythsql_backup.sql is the saved SQL database dump, and the mc.sql file should come from the same version of MythTV that created the database --- even if that is not the version that will be using it!)

mysql -u root -e "drop database mythconverg;"
mysql -u root < /opt/mythtv/mythtv-0.20.2/database/mc.sql
mysql -u root < mythsql_backup.sql

After reinstalling the database, you should probably run mythtv-setup.

Keep a backup disk

A complementary technique --- essential in my opinion, given the time invested in installing the OS, drivers, codecs, and supporting applications --- is to copy the system drive of the main server onto a backup drive. This backup drive should be in offline storage (to prevent destruction in case of catastrophic power surge.)