Frequently Asked Questions

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Revision as of 19:59, 14 August 2006 by Juski (talk | contribs) (Q: Why can't I see all of my desktop/MythTV screen on my TV?)

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

Contents

General Questions

Q: What is MythTV?

See User Manual:Introduction

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

No, the mythtv developers have been working hard.

There is no set release date for MythTV stable builds. They are released when they are considered ready to be released.

v0.19 was released at 0116 UTC, Sunday 12 Feb 2006. v0.20 is under development - see Release_Notes_-_0.20

Q: 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 channel on irc.freenode.net. There are often people around who are willing to help you out when possible.

Hardware Questions

Q: 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.

Q: I upgraded my ivtv drivers to the latest version and now I can't record anything.

In newer versions of the ivtv drivers, namely 0.4.1 and above, the tuner name has changed from Tuner 0 to Tuner. This means that your existing card configuration in MythTV is no longer valid. The easiest way to fix this is to delete all your card data in mythtv-setup and set your cards up again and make sure to redo the Input Connections screen.

Q: 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, OS X, is basically a UNIX derivative, it has been possible to port Mythfrontend to it.

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 theses will probably struggle for tasks such as transcoding and commercial flagging.

Q: 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.

Q: 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

Q: My console/log is full of messages about IVTV DMA errors and some of my recordings are truncated!

This is an IVTV problem. Some motherboard chipsets apparently don't respond correctly to DMA resets. The search for a solution is ongoing. See the IVTV mailing list (http://www.gossamer-threads.com/lists/ivtv/) for details.

Operating System Questions

Q: Does MythTV run on Windows?

The short answer is not really. The long answer is that there has been some work done to get basic frontend capability working on Windows by the win Myth people although the result is still fairly raw at this stage. Another potential avenue has been explored by those wishing to compile Myth on Windows by using cygwin, although as far as I'm aware there hasn't been much success on this as of yet. If you do have a desire to watch Mythtv on a windows box then your best options are:

  • 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.
  • Use MythTV compiled on cygwin - this is still in an early stage of development. Check the MythTV Dev mailing list for updates.

Q: 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.

Q: 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 three 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.

Software Questions

Q: 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.

Q: 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.

Q: 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

mysqlcheck --repair

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.

Q: Are there any Debian (Sid) packages for MythTV?

Please see http://debian.video.free.fr/ for the latest details

Q: 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 any keyboard input while watching a recording/live tv/video file/etc). 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 should save a world of headaches if you ever do have focus issues.

Setting up MythTV

Q: 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).

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

Please refer to the XmlTv page for information on non-US guide data

Q: 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

Q: 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 exception to this rule is the PVR 500 which contains two tuners and consequently counts as two capture cards. 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.

Q: 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

Q: Where have the options for the FF/RW jump sizes gone? They're not where they used to be in the Setup menu.

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

TV Out, Display and Xorg/XFree86 Questions

Q: 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 (?)

Q: 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.
  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. Theoretically this should give you the best output possible, although I strongly suspect the results seen will be dependent on your soldering skills. Instructions on how to make the circuit are here

Q: When viewing video there is an annoying blue border round the side of the screen. How do I get rid of it?

You need a program called xvattr. When your X server starts, run the command:

$ xvattr -a XV_COLORKEY -v 1

Q: 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 resolution at which Myth is designed to operate. To find out what your resolution is use the command:

$ xdpyinfo | grep dots

If the response from this isn't 100x100 dots per inch, you need to change your X configuration file (XF86Config/xorg.conf) file to tell the X server the resolution to use.

Add a line:

DisplaySize x y

Under the "Monitor" section in your xorg.conf. Where x = (horizontal resolution)*0.254 and y = (vertical resolution)*0.254, both rounded to the nearest integer.

If you're using NVIDIA display drivers version 8756 or above and your monitor reports an EDID DPI value, you must tell the drivers to ignore this value. Whereas before 8756, the NVIDIA drivers would use the DPI or DisplaySize setting specified in the X configuration file to set or calculate the DPI--/even if/ your display reported a valid DPI in the EDID information--8756 changed handling of EDID so this is no longer the case. At the same time this change was made, NVIDIA deprecated the IgnoreEDID option (and its synonym "NoDDC")--so take them out of there--and instead use the appropriate options from the list below:

  • UseEDID (boolean): disables the use of all EDID information--equivalent to disabling all the following
  • UseEdidFreqs (boolean): determines whether the driver uses the HorizSync and VertRefresh ranges provided by the EDID
  • UseEdidDpi (boolean): determines whether the driver uses the DPI provided by the EDID
  • ModeValidation (string): if set to "NoEdidModes", will ignore the modeline information specified by the EDID (see the documentation for other settings)
  • DPI (string): specifies the DPI to use for the X and Y axes.

So, for the simplest case with NVIDIA display drivers version 8756 or above, you can specify the following two options in the "Monitor" section of your X configuration file.

Option "UseEdidDpi" "FALSE"
Option "DPI" "100 x 100"

Note that specifying a DisplaySize will have no effect (either positive or negative) when these options are used. Also, you may specify the option "UseEdidDpi" (when using the NVIDIA display drivers) even if your monitor does not report an EDID DPI.

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.

Q: 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.

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

Probably because of overscan. See here: [[1]]

Questions about using MythTV

Q: 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 in the Watch Recordings screen and check to make sure that the View Filter and Group View are both set to All Programs.

Q: 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.

Q: 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

Q: 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: This is not a perfect solution; this switch wasn't actually designed for this, and will break LiveTV at the moment, among other side-effects. The person who wrote this code notes on the mailing list that he expects he might clean it up some after 0.19 comes out. So exercise caution.)

Q: 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.

Q: 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.

Q: 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.

Live TV Questions

Q: 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.

Q: 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 his 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 :)

Links To Useful Information