Frequently Asked Questions

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(Note that there are many collections of Questions and Answers. Some are linked from the sidebar: Robert Kulagowski's Official FAQ/Install Guide. You might want to check those before adding a question -- or answer -- here.)

Contents

General Questions

What is MythTV?

See User Manual:Introduction

Where can I ask questions?

You can ask questions on the mythtv-users mailing list. Make sure you read the Mailing List etiquette page before posting.

You can also try the #mythtv-users IRC channel on irc.freenode.net. There are often people around who are willing to help you out when possible.

You can also try asking questions on an unofficial forum.

Development Questions

Is MythTV development dead? Where is the next stable release?

No, the MythTV developers have been working hard.

Your guess is as good as mine. Isaac typically packages releases at points in time that he feels are stable and a good time for a release. He doesn't do so on a fixed schedule, and so far, we have not gotten any significant advanced notice of pending releases. This is just the way it works.

  • v0.18 was released on Friday 15 April 2005.
  • v0.19 was released on Sunday 12 February 2006.
  • v0.20 was released on Monday 11 September 2006.
    • v0.20.1 was released on Saturday, April 28, 2007
    • v0.20.2 was released on Friday 24 August 2007, and supports Schedules Direct
  • v0.21 is now under development, see Release Notes - 0.21.

Does MythTV have a bug tracker?

Why, yes it does. It is located at: http://svn.mythtv.org. This is a website running Trac, which merges together a ticketing system with Subversion version management tools. You can even browse the source code through this page.

What has changed in SVN since blah (time/revision)?

Undoubtedly several things have changed in SVN. If you are interested in knowing the changes, your best bet is to subscribe to the mythtv-commits mailing list and read the commit messages as they come out.

If you are compiling from source, you can run "svn log -rBASE:HEAD" from the svn working copy to see the commit logs since you last upadated.

When will MythTV be ported to QT4?

The short answer is, a very long time.

QT4 involves thousands of changes to get working, and it will take a long time for those changes to be made. Even starting the changes is difficult, once started mythtv will not function until they are complete and no other work can be done during this period.

Please see threads on the mailing lists:

Words from Issac Mythtv-users Mythtv-dev

When will Myth reach 1.0?

Whenever the developers decide it's time. There's no set reason or list of things to do before 1.0. It's just not time yet and that's all that can be said.

Myth should be released more often! Why wait so long?

Because it's run by people donating their time and they have their reasons. You can put up with it, or you can do your own release schedule. The source is stilling there, waiting for you to do whatever you want. Just don't bother bringing it up on the mailing lists or irc. It's a long dead horse. Let it rest in peace...

MythTV Operational Questions

Can I use SVN frontend/backend with release X frontend/backend?

Short answer: not usually.

Slightly longer answer: not usually, and never recommended.

Quite often, SVN changes will incorporate database schema changes and/or backend protocol changes. All of your frontend/backend/mythweb/DSMyth installs must use the same database schema and backend protocols, or things will surely break.

This means that all parts of MythTV (mythtv, mythplugins, and myththemes) should be installed from the same SVN revision or release version. Likewise, all computers running MythTV on your network (the master backend, slave backends, combined frontend/backend systems, dedicated frontends, etc.) should use the same revision/version. Therefore, when using packaged versions of MythTV, you should use the same distribution on all systems.

Note, also, that there are multiple branches of development in SVN. At a minimum, these include 0.XX-fixes (which is usually used for packaged "binary" versions of MythTV) and SVN "trunk" (the main development branch). You should never mix components from different branches. Therefore, even if you acquire a specific SVN revision from both 0.XX-fixes and SVN trunk, you must choose to use either the 0.XX-fixes or SVN trunk branch for all your systems.

If you do try to mix and match revisions or branches of MythTV code, debugging problems is your own responsibility. If mixing and matching revisions or branches of MythTV code breaks your data (doing so could corrupt the database that includes all of your MythTV usage data including lists of recorded programs and recordings available for watching), fixing the broken data is your responsibility.

How can I go back from SVN code to release X?

I hope you backed up your database before the upgrade to SVN code. See the "Miscellaneous" section of the MythTV Documentation for more details.

You will likely need to recreate your database as the SVN code will have upgraded it automatically, and the old release code won't likely work with it. If you saved your old database, dump the database and reinsert the old one. If you didn't save your old database, good luck. You may have to just recreate the database as if you just installed for the first time.

While it may seem that MythTV works fine after downgrading versions, any data being added to your database is likely being corrupted. And--if nothing else--new data is being inserted into the database in the old format. Therefore, running MythTV with the "upgraded" database after downgrading versions is a time-bomb. While MythTV may work fine now with the older version, it will surely fail when you upgrade later. So, the longer you run in this broken state, the more data you'll have to fix (or the more data you'll lose) when you later upgrade. Therefore, regardless of whether you think it's working, you should always revert back to the pre-upgrade database (from your backup) when downgrading MythTV versions.

Do I really need this backend thingie?

Strictly speaking, no, you do not, but only a few things will work.

Does the backend need to be running all the time?

If you are looking for the easiest solution then yes, it can't record when it is not running!

If you don't mind a challenge, then no, but you need to consider whether the hassle of starting mythbackend at the right times is worthwhile. If you want to shutdown the computer completely you might use Wake On Lan or a bios wakeup timer, but this can be complicated and unreliable. See Shutdown Wakeup, ACPI Wakeup and Mythwelcome for more details.

Well then, what about this mysql thing?

MySQL is required for the frontend and the backend. It stores all the data they need to run and to do things, so yes, you will need it running whenever the backend or frontend are being used, which typically is all the time (see previous question).

Hardware Questions

I can't get <insert component here> working. Help!

A tried and true rule: Get it working outside of MythTV before you try to get it working inside.

MythTV isn't an operating system. It requires working components to work. You would never try installing a PVR application on Windows before you got your video card, capture card, and audio system working perfectly. Don't try to do it on Linux.

Confirm that all of your hardware is working with an application outside of MythTV before attempting to run MythTV. It will save you innumerable hours of barking up the wrong tree and generally make your MythTV experience better.


I want a low power, quiet computer to use as a frontend. What are my choices?

Probably the best two choices are the Mac Mini and computers based around the mini-ITX form factor.

The Mac Mini is Apple's small form factor computer. It has the benefit of looking extremely nice and being extremely small. While it does have a fan, this is generally regarded to be so quiet that it is not an issue. Power consumption is low (Tom's Hardware quotes 28W while playing DVDs) and since the operating system, Mac OS X, is basically a Unix derivative, it has been possible to port Mythfrontend to it. The newest models of the Mac Mini use Intel's Core Duo processor, which means - using Apple's BootCamp - it is now possible to install LINUX on the Mac Mini and run the full MythTV backend system, as well as the frontend.

The mini-ITX systems (often referred to as EPIA or VIA Eden boards) are another small factor computer, this time based on the x86 instruction set. They are not quite as small as the Mac Mini, but still pretty tiny and again they are very low power which is good for any computer that's going to be left on all the time. They come with a range of processor speeds (between 600MHz and 1.4GHz) although the processing power is less than would be achieved with the equivalently clocked Intel chip. With the lower power chips it is possible for them to run fanless, although these will probably struggle for tasks such as transcoding and commercial flagging.

Can I use MythTV without using my cable / satellite companies provided cable box?

United States:

  • Normal Analog Cable: Yes, you can usually use MythTV without their provided cable box.
  • Digital Cable, analog channels: In many cases you can tune the analog cable channels off the same line, but sometimes you will need to use the cable box.
  • Digital Cable, digital channels: Certain cards, such as the pcHDTV 3000, can receive non-scrambled QAM-256 channels. These will generally only be your local HDTV channels. For all other channels you will need the cable box and an analog capture card.
  • Satellite: No, you will need the satellite box.

Since I need to keep using my Cable/Sat box, how can I control it with MythTV?

A few different ways, and it depends on your specific hardware and the provider. Possibilities include Serial Control, USB Control, FireWire Control, and IR Blaster (using the PC as a programmable IR Remote Control). See the HOWTO for details. At least some models of the Hauppauge PVR-150 include an IR output capability.


Operating System Questions

Does MythTV run on Windows?

The short answer is not really. What program really does work properly on Windows? Currently, the best solution has been MythTvPlayer, but that is not really MythTV - just a frontend to recordings on a Mythtv Backend. Many people are optimistic that eventually, we'll have mythtv running well enough under cygwin to actually be able to have binaries for a full mythtv frontend. In the meantime, if you want to watch Mythtv recordings on Windows, your best options are:

  • Run MythTvPlayer
  • Run mythstream. This will allow you to stream video from your backend to a Windows Frontend, on which you can use mediaplayer etc to watch the video.
  • Use Knoppmyth. This will allow you to boot up your windows box into mythfrontend in a way that won't touch you hard drive (so when you take the CD out and restart you'll go back into windows).
  • Use DS Myth. This is a series of direct show filters and applications, which enable the .nuv files created by MythTV to be played back on windows.
  • Use Tapeworm and VideoLAN. Tapeworm uses a mySQL connection to query and display recordings and a Samba share to launch your media player with the appropriate file.
  • Or use MythWeb and VideoLAN - With a few modifications, MythWeb with clickable thumbnails, a samba share and some third party software, can bring up the recordings in VideoLan.
  • Use MythTV compiled on cygwin - this is still in an early stage of development. Check the Trac Ticket 1590
  • Use MythTV running inside a Linux Virtual Machine running inside Windows. Tests using the free for personal use VirtualBox virtual machine show that this solution can work quite well. It's quite usable with a VM screen resolution size of 640x480 or 800x600. Adding realtime deinterlacing or larger screen sizes can result in some choppiness in the video playback. (tested with MythBuntu 7.10 running in VirtualBox 1.5.2 on Windows XP on an Athlon 64 X2 3800+ based system.)

Does MythTV run on Mac OS X?

Yes, but most recording devices will only work under Linux, so by default only the frontend is compiled.

Which Linux distribution should I use?

If you are already comfortable with Linux then it's probably best sticking to the distribution you know best. If, however you're a Linux novice then the best bet is to go with one of the following five options:

  1. Fedora. Jarod Wilson has written what is almost certainly the best guide to getting MythTV up and running and he's done it based on Fedora. Find out more here.
  2. KnoppMyth. This is a version of Knoppix bundled with all of the stuff needed to get Myth up and running.
  3. MythDora. This is a custom based version of Fedora that will install MythTV for you. Everything that you need is right on the disk along with some extras.
  4. SuSE Offers an easy to use straight forward interface.
  5. Ubuntu The latest releases of Ubuntu feature full support for MythTV. Its ease of installation and use has made it very popular among the LINUX desktop crowd.

This is one of the most hotly disputed topics on #mythtv-users (other than politics or religion). All Linux distributions that are capable of installing or compiling all of the prerequisites are usable. Asking for advice in choosing a distro is ill-advised as many of us have strong opinions based on our usage requirements, and these requirements will likely not match yours. However, Fedora and Debian are some of the most used, and easiest to work with.

Please also note that if you choose an obscure, unknown distro, not many people will be able to help you with distro-related issues.

Software Questions

Why is X taking 100% CPU just drawing the frontend menu?

A1: If you compiled X yourself you may have used -Os or another problematic optimization flag. Use -O2 when compiling Xorg 6.8 through 7.1.

A2: If you enabled OpenGL menu drawing, then this is probably because you do not have hardware accelerated OpenGL working.

I upgraded X, Y, and Z and now everything is broken. Help!

The one piece of advice I can most often give Myth users is to keep it simple. Distribution packages, automatic installers, and many other Linux packaging features have made it very easy to get a MythTV system installed by even the most novice MythTV user. This does not mean that you should arbitrarily run apt-get/yum upgrade on a whim and install every package update that is available to you.

MythTV is designed as a PVR appliance, first and foremost. Once it is working, it should be hands off, even for what seems the most innocent of upgrades. As tinkerers, most of us can't resist installing the lastest this, or the newest that. But more often than not, a mass upgrade of every component on your system leads to trouble.

If it ain't broke, don't fix it

It may sound simple and foolish, but many people will tell you that once you have your MythTV system working, don't upgrade anything other than the MythTV application unless you absolutely have to. If you want to tinker with the latest of everything, build a slave backend and mess with it there.

Do I need to have X-windows installed on my backend? I don't want it.

MythTV requires Qt
Qt requires X-windows

You are not required to boot into graphical mode (see the documentation for your operating systems for details on how to boot to a console login). The mythtv-setup program run on the backend system is a graphical interface. You can either run this locally on the backend or use X11 forwarding to display the output of the program on another system.

And if you're concerned about the space that X-windows takes up, consider for a moment that your entire system is built to process multi-gigabyte files, a few megabytes for X-windows is a drop in the bucket.

Why am I getting QMYSQL3 errors?

QSqlDatabase warning: QMYSQL3 driver not loaded
QSqlDatabase: available drivers: 
Unable to connect to database!
No error type from QSqlError?  Strange...
couldn't open db

There are actually a few causes for this error that all revolve around the same basic problem, and that problem is that your Qt binaries are missing their MySQL support (which is required by MythTV). If you have Qt-3.3.x, either your Qt was not compiled with MySQL support (via -plugin-sql-mysql if you compiled it yourself), or you've accidentally left out the sub-package containing libqsqlmysql.so. If you have Qt-3.2.x, it's possible that the plugin is actually present but not in a directory your library linker has been searching.

To determine if the Qt MySQL plugin is actually present your system, run the following command:

   find /usr /opt -name libqsqlmysql.so 2>/dev/null

If this command returns a filename (and you are using Qt-3.2.x) then you probably need to add this directory to the list of places your system's linker searches. So for example if it returns "/usr/lib/qt-3.2.1/plugins/sqldrivers/libqsqlmysql.so" you would add "/usr/lib/qt-3.2.1/plugins/sqldrivers/" (without the quotes) to /etc/ld.so.conf and then run `ldconfig` to rebuild the linker's cache.

If however it returns nothing then depending on your Linux distribution, adding this support may be as easy as installing a package (qt-MySQL for Fedora Core for instance, libqt3c102-mysql on Debian Sarge) or as nasty as recompiling Qt yourself with support for it. In Gentoo, putting 'mysql' in your USE flags and doing 'emerge qt' will also solve this problem.

I get a database 145 error. What is it?

Errors that look like this

QMYSQL3: Unable to execute query
Database error was:
Can't open file: 'inuseprograms.MYD'. (errno: 145)

An errno of 145 mean a corrupted database table. The mysqlcheck program from MySQL is used to repair tables. If mysqlcheck finds errors, you can run either (you will be promted for your database password)

mysqlcheck -u root -p  --repair mythconverg

or

mysqlrepair

to repair damaged tables. Be advised that sometimes repairs can cause data loss. It is always recommended that you perform a database backup often so that if problems arise, you have something to restore.

Are there any Debian packages for MythTV?

Please see http://www.debian-multimedia.org/ for the latest details. Packages for stable (etch), testing (lenny) and unstable (sid) are provided.

For information how to adapt your /etc/apt/sources.list file, see at the bottom of that page!

Do I really need a window manager for a frontend only box?

Of course not, but you are very likely to run into focus issues (the frontend won't receive keyboard and/or remote input while watching a recording/live tv/video file/etc), so running without a window manager is an unsupported configuration. There are plenty of very light-weight window managers, such as LWM, TWM, Ratpoision, blackbox/fluxbox/*box, XFCE, and so on. Using one of these should never impact your performance, and will prevent invalid "bug" reports of focus issues that are actually due to not using a window manager.

To put things in perspective, after accounting for shared libraries that you need to load for other parts of X/MythTV, the incremental cost of running FluxBox is less than 1MB of RAM. The incremental cost of running RatPoison is only 300KB. If your system needs that 1MB or less of RAM, that's not all the RAM it needs (so you're better off getting more RAM than trying to run without a Window Manager). See, also, http://www.gossamer-threads.com/lists/mythtv/users/230352#230352 and http://www.gossamer-threads.com/lists/mythtv/users/230354#230354 .

How can I get DVD menus to work?

If you are using an older install of MythDVD you may still be using mplayer to play DVDs. Mplayer doesn't support DVD menus. MythDVD now uses an Internal player to play DVDs which supports all DVD functionality including menus. If you change the DVD Player Command from mplayer to Internal (Capital I) you should be able to use DVD menus.

Why is my guide an hour ahead after Daylight Savings Time?

A bug in Qt was worked around in MythTV, but that bug was fixed in Qt 3.3.4. You can downgrade your Qt to 3.3.3 or patch MythTV with the patch found here. If you use Gentoo, you can also download an ebuild and a patch there, and update MythTV.

How do I remove recordings that no longer exist on disk?

If you have deleted some of the .nuv files, or put a new disk in, you have probably noticed that you can no longer delete the recordings from within the frontend. If you want to clean the recordings out of the frontend, you can run the following command from within your recordings directory:

for line in `mysql -u mythtv -pmythtv -e 'SELECT
CONCAT(chanid, "_",
       date_format(starttime, "%Y%m%d%H%i%s"),
       "_", date_format(endtime, "%Y%m%d%H%i%s"),
       ".nuv") AS filename FROM recorded;' \
mythconverg | grep -v filename`;
do if [ ! -f $line ]; then touch $line; fi; done

Which will touch each recording file that should exist if it doesn't already. All this does is create an empty file so that the frontend has something to delete.

How long is mythfilldatabase take to run? It seems to be stuck in a loop?

It can take a few minutes to a long time, depends on how much data and where you are getting it.

It's actually not stuck in a loop, it grabs data for each day, processes it and goes onto the next day, so don't worry about it looking like it's stuck in a loop, it's really not.

Setting up MythTV

What are the types of channels I can record and what type of capture card(s) do I need?

In general, channels are received by mythtv through either an antenna connection or a cable connection to the capture card(s). To find channels in your area, you can do a search using labs.zap2it.com. You will be able to determine which channels are over-the-air broadcasts (whether NTSC, digital TV (DT) or High Definition (HD)). For example, you may find that your cable provider provides you with "Channel 10 KXXX", and "Channel 10 KXXXDT". The former is an NTSC broadcast and the latter is a digital broadcast.

In general, you should be able to receive at least one digital signal per local station that you can receive normally over the air.

To capture NTSC broadcasts, you will need a card like the PVR-350. That card cannot recognize digital or HD broadcasts. To capture those, you will need a card such as the pcHDTV 3000 (although the pcHDTV 3000 also has the capability of capturing NTSC as well).

If you live in an area where Digital Terrestrial Television (DTT, also known as DVB-T) is an option, then this is a particularly good option, as the received signal is already MPEG-encoded, lowering CPU requirements for the backend. The author of this paragraph has measured recording three 4.5Mbit/s DVB-T channels simultaneously as requiring about 7% CPU on a Celeron 1.7 machine (using Hauppauge Nova-T and Nova-T-500 tuner cards on FC8rc3).

Where do I get my TV guide data outside the US?

Mythtv can integrate with a separate set of scripts maintained by the XmlTv project to provide guide data for countries outside the USA. Please refer to the XmlTv page for more information. For digital broadcasts, Mythtv may alternatively use the Electronic Programme Guide data broadcast as part of the DVB or ATSC specification, known as generally as EIT.

How do I view/record video through Composite/SVideo?

  • First verify if works outside MythTV eg test with TVTIME, These devices may be supported by Video4Linux (V4L).
  • Configure using mythtvsetup

How many capture cards do I need?

Basically you need one capture card for each program you wish to record at any given time, and one extra, if you want to simultaneously watch live TV. The exceptions to this rule are the PVR 500 which contains two NTSC tuners and the HDHomeRun which contains two ATSC/QAM tuners; they consequently count as two capture cards each. Examples:

  • With a single capture card you will be able to record a single program or watch live TV at any given time
  • With three capture cards you will be able to record up to two programs whilst still having the ability to watch live TV. You may then begin recording a third program but will then lose the ability to watch live TV.

How much disk space do I need?

The short answer is as much as you can afford. If, however, you're not made of money, here are a few guidelines:

  • Video recorded via a PVR x50 typically comes in at 2GB/Hour
  • Standard Def DVB will typically be 1.2-2GB/Hour
  • High Def video will be somewhere between 3.5GB and 7GB/hour

Where have the options for the FF/RW jump sizes gone?

This functionality has been moved to the Playback Groups setup menu. Here you can create Groups to apply different skip, jump and stretch to any programs you want. You'll find it at Utilities/Setup -> Setup -> TV Settings -> Playback Groups

MySQL sucks! Can I use a different database?

No. Supporting multiple database engines is not considered a worthwhile use of the developers time. Furthermore, simple or lightweight databases like SQLite just can't cope with myth's needs.

It is planned that in the future Mythtv will move to use embedded mysql and running a seperate mysql server will no longer be necessary.

TV Out, Display and Xorg/XFree86 Questions

I'm using the TV-Out on the PVR 350 and I can't see dialog Boxes

If dialog boxes do not appear when you press play, pause etc with a recent ivtv driver, then you should activate ivtv osd compatibility. You need to specify the option osd_compat=1 when loading the ivtv-fb module (see ivtv driver README).

I'm using the TV-Out on the PVR 350 and X is larger than the screen. Parts of the desktop and Myth interface are cut off around the edges

Currently the IVTV X driver only supports being run in full screen mode (720x 576 or 480). This will result in some of the picture being lost due to overscan. The way to fix this for MythTV (but not X in general) is to play about with the GUI X/Y size and displacement options under settings>playback settings (?) --merlin: recommended values that worked for me for a PVR 250 were: x/y offsets:+26/+18 width/height: 646/450

What are my options for connecting my computer to my TV?

Ok firstly I'm not really going to touch upon High Def here because it's something I know little about. Secondly a full description of how to get perfect TV out is beyond the scope of this how to so I'll just stick with the basics. If you're really interested, however, go to the mythtv-users mailing list archive and search for posts by Cory Papenfuss. He explains it better than I ever could. Anyway your options are:

  1. TV out on a graphics card.
    Lots of graphics cards come with a TV out these days, usually in the form of an S-Video out which can then be converted to SCART if you live in Europe. The main piece of advice is to ensure that the graphic card you thinking of has Linux drivers that support the TV out functionality (until very recently some ATi cards had problems with this). If you've got a free choice, the best way to go is probably with an Nvidia based card, on the grounds that they have good Linux support and they're used by many of the developers. If noise is important to you then try and get one without a fan.
  2. TV out on the Hauppauge PVR 350.
    Unlike all the other Hauppauge cards, the PVR 350 includes an S-Video out socket on the back of the card. The big advantage of using this is that the quality of the picture you get form the PVR 350 is generally regarded as being the best available. The bad news is that the PVR 350 doesn't have any Open GL support, so if MythGame is going to be a large part of your life, this route probably isn't for you. Also, MythTV will soon be going to OpenGL for the menus, so it will not be supported at all for that.
  3. A Scan converter
    This is a single box, which converts the VGA signal from your video card into NTSC/PAL/SECAM for your TV. This has the advantage of working with any graphics card that has drivers available, and is relatively simple, but the output probably won't be frame- or scanline-accurate.
  4. A homebrew VGA to SCART conversion circuit
    If you're a dab hand with a soldering iron and you live in Europe then you can cheaply make a circuit which will enable you to take the VGA output of the video card and plug it straight into the SCART socket on your TV. This should give you the best output possible (other than direct VGA!), although I strongly suspect the results seen will be dependent on your soldering skills. Instructions on how to make the circuit are here. nVidia GeForce 440MX cards work well, and a fanless design is preferred. The author of this paragraph recommends using Linear Blend deinterlacing, rtprio scheduling (by editing limits.conf), disabling OpenGL sync in MythTV, but leaving the video texture and video blitting sync options in nvidia-settings set. Note that you may need to modify the On-Screen Display themes and MythTV GUI appearance settings to make sure the graphical elements are properly framed on your TV. Recommended PAL modelines are:


ModeLine "1024x576pali" 19.750 1024 1056 1152 1264 576 581 586 625 -hsync -vsync interlace # 16:9
ModeLine "720x576pali" 13.5 720 722 786 864 576 581 586 625 -hsync -vsync interlace # 4:3 DVB
ModeLine "768x576pali" 14.75 768 789 858 944 576 581 586 625 -hsync -vsync interlace # 4:3 Analogue

  1. Direct VGA connection.
    If your display supports it (some LCD TVs have a VGA input) this input type is simple, but you may be limited with supported resolutions. This is a particularly a problem, for example, if your TV is widescreen, but only accepts 1024x768.
  2. Direct DVI connection.
    Many video cards have a DVI connection these days, and it's available on some TVs as well. There is the possibility of limitations with supported resolutions for this case as well.
  3. DVI to HDMI cable.
    This is a fairly attractive solution, as HDMI inputs are a current standard for High Definition sets. This is just a simple cable with a DVI connector that plugs into a compatible video card at one end, and the HDMI input to the display on the other end.

All my fonts look like they are the wrong sizes, how can I correct this?

The first thing to do is to make sure that the X Server is running at 100x100dpi as this is the pitch (DPI) at which Myth is designed to operate. To find out what your vertical and horizontal pitch is (with the display running) use the command:

$ xdpyinfo | grep dots

If the response from this isn't 100x100 dots per inch, you need to change your system configuration to force X to calculate dimensions appropriately for Myth usage. Unfortunately, there are many ways to specify the pitch, but X will use only one. The "-dpi" command-line argument to the X server takes precedence over all others. Note that some distributions use this argument in their X start scripts (such as the "startx" script) or by calling "startx -- -dpi 75". If your distribution does this, you'll need to modify the start script to either specify 100 DPI or simply remove the option (preferred) and use the configuration files as described below.

If your system does not specify a command-line argument to set the DPI, you should configure the pitch using the X configuration file (XF86Config or xorg.conf, usually in the /etc/X11/ directory ). The standard X approach for configuring the pitch is through the "DisplaySize" setting. This approach will work with all video card drivers (if using an NVIDIA card, however, see below). To set 100x100 DPI with the DisplaySize option, add a line:

To force a system wide usage of 100 dpi you can add the following line "Xft.dpi:100" to /etc/X11/Xresources. If you like to limit it for an user only use ~/.Xresources.

DisplaySize x y

Under the "Monitor" section in your X configuration file. Where x = (horizontal resolution)*0.254 and y = (vertical resolution)*0.254, both rounded to the nearest integer. See the Display Size page for appropriate settings for common monitor and TV resolutions or if your display is using non-square pixels (i.e. the ratio of the physical display's dimensions are different from the ratio of the X and Y resolutions). It's important to choose a DisplaySize whose aspect ratio is the same as your physical display's aspect ratio, so if you have a 16:9 TV, choose a 16:9 DisplaySize. If you have a 4:3 TV or monitor, choose a 4:3 DisplaySize.

If you're using NVIDIA display drivers, see, also, the section Specifying DPI for NVIDIA Cards

If this doesn't solve the problem then the chances are it's a broken font package or something. Feel free to post the problem to the mailing list at this point, but make it clear you know you're running at 100dpi or you'll get lots of requests telling you to make the changes listed above.

Should I use the mailing list to find out where I can download TV shows/Films?

No. When you use MythTV you will find out that it is a very useful piece of software that can completely change the way you watch TV. It is not, however, a means to circumvent copyright and this list is no place to be asking for tips on how you should do so.

Why can't I see all of my desktop/MythTV screen on my TV?

Probably because of overscan. See here: Overscan

Questions about using MythTV

I'm getting a protocol mismatch. What is wrong?

You are running different versions of MythTV on your frontend and backend. This occurs when a protocol change is implemented as part of a MythTV release. Update your systems to the same version to prevent this problem.

Why aren't my new recordings showing up in Watch Recordings?

You probably have a filter set on Watch Recordings from a previous session. Hit MENU (press M on your keyboard) in the Watch Recordings screen and check to make sure that the View Filter and Group View are both set to All Programs.

How do I import recordings from other sources into Myth?

In the contrib folder of the MythTV sources, there is a script named myth.rebuilddatabase.pl which takes an "--ext" command-line option followed by a file extension. This will prompt the script to search for those files that match the extension and prompt you for information about them to import them into the database along-side your existing recordings. or use MythVideo to import videos.

I have no interest in recording Tv but I wish to use Myth as a music/video jukebox. Is this possible?

Yes. Myth has two plugins called MythMusic and MythVideo which can be used to handle video and audio libraries respectively. You will still have to install both Mythfrontend and Myth Backend, however Myth will work perfectly well without any capture cards installed

Can I temporarily keep MythTV from attempting to record my scheduled programs?

If you're going to, for example, have your cable TV feed temporarily disconnected, and you don't want to record static, but you don't want to lose your schedules:

A1: Go to the "Upcoming Recordings" page of the frontend (or MythWeb) and add a "do not record this episode" override for each scheduled recording during the expected service outage. (This solution will not work for episodes with empty subtitles or descriptions because they are exempt from duplicate checking. You can simply delete these recordings after they have occurred and they will have no impact on future recordings.)

A2: Use the frontend or MythWeb to edit each recording rule and set the "Inactive" flag. If you're comfortable with typing MySQL commands you can update all of your rules at the same time by entering the following command at the MySQL prompt:

update mythconverg.record set inactive=1;

Set inactive=0 to resume recording. This method simply updates all existing rules. Any rule-changes or episode overrides created after this SQL command is entered WILL be actioned. (Note: Whenever you change the recording properties directly in the database you must force MythTV to re-read the recording rules. This can be done by restarting the backend program, by signalling a running backend using "mythbackend --resched" or by making a trivial change to the schedule using MythWeb or a frontend.)

A3: Modify whatever starts your machine's backend to add the --nosched flag, like this:

mythbackend --nosched

This will cause the backend to run normally, but not execute scheduled recordings. When your problem has been cleared up, remove or comment out that switch. (Note: In 0.20 and prior, this was not a perfect solution; this switch wasn't originally designed for this, and would break LiveTV, among other side-effects because the scheduler was not even started. In 0.21 (when it is released) and later, the --nosched switch works much better. The full scheduler will run allowing LiveTV, testing, etc. to work properly, but no recordings will actually fire off.)

Myth won't record a later showing of a program

The scheduler, by default, will not bump programs of higher priority even if there is a later showing as it assumes that you want to see higher priority shows sooner rather than later. If you feel it is acceptable to bump them, there is a setting in the frontend setup to allow rescheduling of higher priority items that can be checked. Just be aware, that exciting episode of 24 might be recorded a week or two later leaving you in the dark and plugging your ears as your friends talk about it.

Myth won't recognize when I insert a CD or DVD

First, make sure that the media monitoring is checked in the general settings. Also make sure that it is enabled in the plugins for MythDVD or MythMusic. Lastly, check if your mount point for your drive is set to use filesystems of "udf, iso9660" instead of "auto" which can correct problems with lowercase directory entries failing to be detected on DVDs.

Myth removes commercials but when I watch the file elsewhere or transcode, the commercials are still there. Why?

See Removing Commercials for details. The simple answer is, because commercial flagging is flagging, not removal.

Changing the volume and muting doesn't work, what should I do?

Ensure that you've got the correct audio output device. To route audio through the default ALSA Mixer, change /dev/dsp to ALSA:default. To route the audio through JACK, change the setting to JACK:

How can I get my channel icons?

Please see Channel_icons.

Why can't my remote frontend play recordings even though I can see them in 'watch recordings' ?

Ensure that all your MythTV machines have different hostnames. Myth works out whether or not to stream a recording (live tv or otherwise) by determining the frontend's hostname. If the frontend hostname is the same as the backend's hostname, it will try to play the file 'locally'. Having different hostnames for machines is useful (and correct) in many other scenarios too!

How can I override mythfrontend settings which are stored in the database?

See Override_settings

Live TV Questions

Why is MythTV recording EVERYTHING I watch in Live TV?

MythTV is not your average TV. It's a digital video recorder! When you watch TV, the ability to pause, rewind, and skip commercials is because it is actually recording everything you watch. As an added bonus, when you are watching something and decide you want to keep it, hitting record will just tag the existing recording as a keeper. The LiveTV page has lots more info, but here are the three most FAQs.

But my Harddrive keeps filling up from all these Live TV recordings! How do I stop it from recording?

  • Short answer: You can't.
  • Long answer: You can't stop it from recording, but you can stop it from filling up your harddrive. MythTV is designed with an autoexpire concept. Every time Myth tries to watch or record something, it first makes sure that it has room for it, and will delete the oldest available recording to make space. You can specify how much free space to leave, but it is recommended to dedicate a partition to Myth recordings and tell it to leave at least one gigabyte free. Live TV recordings by default have a shorter lifespan than normal recordings and a lower priority, so they will be expired before any recordings are.

It didn't used to do this, why did it change?

  • It always did. In versions before 0.19, it saved live TV recordings to a separate file (a ring buffer), which stayed within a certain size range. It got complicated when you have more than one tuner and more than one live broadcast being viewed. There was no easy way to transfer from that ring-buffer file into a normal recording, so even though you can pause the TV, there was no way to keep it (and if you paused for long enough, another scheduled recording would come around and wipe out your live TV buffer).

I don't want it to delete things unless I tell it to!

  • You have the option when recording a program to have it auto-expire or not, as well as the ability to change that setting on an individual-recording basis. If no programs are set to auto-expire, however, it will run out of space very quickly.

When using live TV, why is there a delay between the moment I change the channel and the time the channel actually changes?

When you are watching live tv in Myth, you are actually watching content which has first been written as a file to the hard disk. In doing so, the 'live TV' that you are watching is actually TV that has been captured a few seconds beforehand. Whenever you change channel, the old file has to be removed and a new file created. The fact that this takes a couple of seconds is responsible for the gap you are seeing in between channel changes.

Although this doesn't sound too good, it is necessary to create this file so that you can do cool stuff such as pausing and rewinding live TV. The 'approved' method of using live TV is to use 'browse mode' so that you can see what is on any given channel without having to change to that channel itself. The other main answer to this query is that once you have MythTV, you'll rarely use live TV anyway on the grounds that all you favourite programs will be sitting on the hard drive ready to watch.

Of course if you do have any coding skills, there's always the chance to have a look at the code to see if channel changing can be made any faster. You would certainly earn this FAQ writer's gratitude if you did :)

Need to prioritise cards/inputs for live TV

bjm's reply found in mythtv-users:

Note: Input preference has no impact on live tuner selection.

For live, by default it chooses an available card with the same hostname as the requesting frontend. If none, it chooses the lowest numbered cardid that is available. If none it shows a warning message. The default input for the chosen card is initially used. Pressing "Y" switches to the next higher available card and wraps after the highest number. If I have five card and I'm sitting at the host for card 4 while card 2 is in use, it will pick card 4. "Y" changes to 5. "Y" again goes to 1 and again goes to 3.

If the "Avoid conflicts between live TV and scheduled shows" checkbox (found in Setup->TV Settings->General on the first page) is checked, it ignores hostnames and chooses the highest numbered card available. "Y" still counts up and wraps.

For recording, for the same showing with the same priority score, it chooses the lowest numbered cardinputid available for the sourceid of the channel. It there are two single input cards for one video source, the input on card 1 will be chosen unless there is a higher priority show already assigned then it will choose card 2. If the Input preference is higher for cardinputid 2, the showing for card 2 is considered first (priority +1) before the showing on card 1 (priority +0). Therefore the episode wins the spot on the preferred card 2 before the same showing on card 1 is ever considered.

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