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Help and FAQ

Contents

1. Support resources
2. Summary of new features by release
3. Summary of known bugs by release
4. Performance: run as root, use the real-time clock
5. Window manager issues with fullscreen mode
6. FAQ: How do I disable deinterlacing?
7. FAQ: Does tvtime support recording?
8. FAQ: Why is the tvtime window appear blue or black in screenshots?
9. FAQ: Purple lines in video? How do I avoid macrovision?
10. FAQ: Interference problems with soundcards
11. FAQ: Optimal settings for tvtime on TV output

1. Support resources

Interested in tvtime? Having trouble? Have suggestions? Why not hang out with us on IRC at irc.freenode.net, channel #livid. Hope to see you there!

There is also a tvtime mailing list which you can subscribe to, or read on the web.


2. Summary of new features by release

tvtime 0.9.8.5
  1. Some root safety improvements.
  2. Added support for long-format command line arguments.
  3. Added config file options to set startup window position.
  4. Compile fixes for non-C99 compilers and older DirectFB versions.
tvtime 0.9.8.4
  1. Support for norm switching between "compatible" norms for areas which receive both SECAM and PAL format stations.
  2. Added support for the mga_vid driver for the Matrox G200/G400 series cards from mplayer.
  3. Semi-experimental of the X code for better fullscreen support under many window managers. Testing appreciated.
  4. Support for changing the mixer device and channel (see 'man tvtime' and the config file documentation).
  5. Slightly less partial experimental UTF-8 support. Now works with any simple left-to-right scripts which are in FreeSansBold.ttf .
tvtime 0.9.8.2
  1. Fixed all of the known crashes and many minor bugs from the 0.9.8 release.
  2. Updated the look-and-feel of the user interface.
  3. Partial EXPERIMENTAL UTF-8 support. Only works with UTF-8 characters that are also in ISO-8859-1 (Latin-1).
tvtime 0.9.8
  1. New XML config file format for both the tvtime configuration, and the station list.
  2. tvtime now has two distinct half-framerate modes: top-field-first frames, and bottom-field-first frames. This helps with manually deinterlacing 2-2 pulldown or progressive content.
  3. Added support for preset 'modes', which can set the deinterlacer, window size, fullscreen setting and framerate mode.
  4. Added support for custom frequencies in the stationlist.xml file, and a runtime command to add a new station from the current fine-tuning settings.
  5. Added some DScaler DLLs and a wine layer to load these deinterlacer plugins directly without porting to Linux. This gives us the following new deinterlacers:
    1. DScaler: Greedy - High Motion
    2. DScaler: Greedy - 2-frame
    3. DScaler: TwoFrame
    4. DScaler: TomsMoComp
    5. DScaler: Video Bob
    6. DScaler: Video Weave
    We had our own ports of videobob, twoframe, and greedy2frame, but they were found to be buggy. Our ports are currently disabled.
  6. Added the ffmpeg vertical deinterlacer filter.
  7. Support for multiple audio channels (stereo, mono, lang1, lang2).
  8. Included a bunch of fixes for PAL-M support.
  9. Added a slave mode for freevo integration.
  10. Various speedups, quality improvements, and bugfixes.
tvtime 0.9.7
  1. Moved config files into a new config file directory ~/.tvtime
  2. Reworked the frequency tables, merging europe-cable, europe-west, europe-east all into 'europe'. Added the 'russia' frequency table.
  3. Added a channel scanner. F10 walks through the channel list and disables inactive channels.
  4. Added the 'XVideo Bob' deinterlacer filter.
  5. Added lirc support.
  6. Added the overscan feature.
  7. Added hardware support webpage.
  8. Added a half-framerate mode ('=' to activate it).
  9. Fixed alot of bug reports.


3. Summary of known bugs by release

The following is a list of known bugs in the tvtime code itself. For detailed information on known capture driver, X driver, and hardware bugs, please see the tvtime hardware and driver support page.

tvtime 0.9.8.5
  1. tvtime does not modify V4L input volume, so if it is set incorrectly before running tvtime you may not get sound (bug 729964).
  2. tvtime does not support the standard -geometry command line option (bug 727947).
  3. tvtime does not support the standard -display command line option (bug 727946).
  4. tvtime does not support the linux-dvb driver (bug 694544).
  5. dalias' pulldown detection algorithm is currently disabled (bug 751093).
  6. No support for PAL-60 (bug 729660).
  7. No runtime norm switching for non-compatible norms (PAL/NTSC switching) (bug 743918).
tvtime 0.9.8.2
  1. Toggling fullscreen nukes AlwaysOnTop setting in kwin (bug 720300).
  2. Luma correction broken if using Dalias' pulldown detection (bug 726822).
  3. if using less than 4 gbuffers, tvtime shows a blue frame as you change channels (bug 690473).
  4. font aspect ratio is not updated if you toggle the aspect ratio at runtime (bug 628943).
  5. We have not written MMX versions of many functions that we do have MMXEXT versions of, as such, performance is much worse than it should be on older CPUs (bug 630236).
  6. tvtime does not notify the user when frames are being dropped (bug 633235).
tvtime 0.9.8.1
  1. Compile is broken for pre-gcc3 (bug 731932).
tvtime 0.9.8
  1. README incorrectly lists 'b' as channel_renumber key when it is really 'r' (bug 729675).
  2. xscreensaver shutdown code does not work (bug 729718).
  3. kscreensaver code is disabled as it is too slow (bug 727990).
  4. Fullscreen the wrong size if using Xinerama (bug 726820).
  5. Toggling fullscreen nukes AlwaysOnTop setting in kwin (bug 720300).
  6. Luma correction broken if using Dalias' pulldown detection (bug 726822).
  7. Network name and call letters from XDS not displayed (bug 729588).
  8. if using less than 4 gbuffers, tvtime shows a blue frame as you change channels (bug 690473).
  9. font aspect ratio is not updated if you toggle the aspect ratio at runtime (bug 628943).
  10. We have not written MMX versions of many functions that we do have MMXEXT versions of, as such, performance is much worse than it should be on older CPUs (bug 630236).
  11. tvtime does not notify the user when frames are being dropped (bug 633235).
tvtime 0.9.7
  1. greedy2frame and twoframe deinterlacer ports are buggy and show splotchy pixels all over the place and should not be used (bug 704780).
  2. The FineTuneOffset configuration file parameter is completely ignored (bug 707278).
  3. configure does not fail if gcc, g++, or X libraries/development headers are not found (bug 696067).
  4. "enter" mistakenly missing from command list, can't be sent using the fifo (bug 708596).
  5. There are many known issues with fullscreen support under various (buggy) window managers. See section 5, Window manager issues with fullscreen mode.
  6. tvtime does not resize properly to compensate for of non-square-pixel displays (bug 690428).
  7. tvtime does not resize properly to compensate for 16:9 aspect ratio monitors (bug 636423).
  8. if using less than 4 gbuffers, tvtime shows a blue frame as you change channels (bug 690473).
  9. font aspect ratio is not updated if you toggle the aspect ratio at runtime (bug 628943).
  10. We have not written MMX versions of many functions that we do have MMXEXT versions of, as such, performance is much worse than it should be on older CPUs (bug 630236).
  11. If not using 720 pixels/scanline input sampling, tvtime does not render volume/data bars correctly (bug 632781).
  12. tvtime does not notify the user when frames are being dropped (bug 633235).
  13. tvtime renders the output even when the window isn't visible, keeping the CPU usage high even if it's on another desktop or minimized (bug 705989).
  14. Rendered strings in the OSD seem to have some pixels missing from the right hand size (bug 693642).
  15. No way to set the audio mode (mono, stereo, SAP, etc) (bug 709505).
  16. tvtime ignores locale information for time format (bug 710875).
  17. tvtime does not support frequencies used by the UPC cable provider (bug 711434).
  18. tvtime cannot renumber channels (bug 711431).
  19. tvtime does not clean up its shared memory segments, eating memory (bug 711470).
  20. XDS information remains on-screen when you switch to an input with no tuner (bug 699810).
  21. Time and network information is not right justified (bug 711654).
  22. tvtime prints errors on change of deinterlacer (bug 715997).

4. Performance: run as root, use the real-time clock

For optimal performance, tvtime should run as root, either by logging in or using su to become root, or setting the executable setuid root. As root, tvtime can:

  1. Reset the process priority to one which gives highest priority to the tvtime process, the specific value can be set in the tvtime.xml file. Many high priorities are only available to processes with root access.
  2. Aquire realtime priority by entering into the SCHED_FIFO scheduling queue, where tvtime will be allowed to processes video uninterrupted by other processes. This is most important when using deinterlacers that eat up alot of CPU to make sure that tvtime does not drop frames.
  3. Running as root automatically gives you access to 1024hz resolution from the real-time clock device.

Note that if tvtime is setuid root, we will drop root priviledges after aquiring all of the performance enhancements we need, making it slightly more polite.

Support for the real-time clock device is needed for smooth video. We STRONGLY recommend that you load the rtc kernel module before starting tvtime. The following command will tell you if rtc support is available:

    cat /proc/driver/rtc

If this file exists, then the real time clock driver is loaded. Otherwise, please load it by typing:

    modprobe rtc

Or add it to your /etc/modules file to have it loaded on every reboot. For smooth video, make sure you run as root, but if you are uncomfortable with this, you can let tvtime access high resolutions from the rtc device by executing the following command:

    sysctl -w dev.rtc.max-user-freq=1024

Note that this setting is lost on reboot, so this should be added into your system startup scripts. Consult your Linux distribution documentation for how to do this correctly on your system.


5. Window manager issues with fullscreen mode

Like many other video applications, we have been plagued with problems due to fullscreen support in various window managers, and would be anxious to hear about any problems or suggestions. Known problems at this time are:

  1. kwin from KDE 3.1: kwin has a nasty bug, we have a workaround, but the workaround is failing sometimes when running as root at high priority.
  2. FS broken with metacity in RH 8.0: The metacity shipped with RH 8.0 had bugs which have been fixed in later versions of metacity.
  3. FS goes off centre when mouse moves: If you're fullscreen at a lower resolution than your root window, moving the mouse causes the virtual to scroll, leaving the window off-centered.
  4. FS problems with icewm: We still seem to have some minor problems with current versions of icewm.
  5. Problems with fvwm 2.4.0: A user has reported some weird X errors using fvwm 2.4.0, I have not reproduced them using fvwm 2.4.10.


6. FAQ: How do I disable deinterlacing?

I think there is a misconception about what the deinterlacing plugins do and what it means to disable them. The signal output from almost any video source, be it a Gamecube or cable TV, is an interlaced video signal. Implicitly when you display this on a computer screen, you are deinterlacing: you're taking interlaced content and sending it out to a non-interlaced display.

The simplest way to do this, and the default if you use xawtv in overlay mode, is to buffer every two consecutive fields together and show them as a single frame. You can do this in tvtime by using the Weave plugin, and hitting the 'half framerate' button. That's about as close to "not deinterlacing" as you can get, but it's still deinterlacing.

However it's worthy to mention that detecting progressive content sent over an interlaced channel, as will happen with some video games, or DV cameras in progressive modes, is still deinterlacing and is something we don't really do right now, except by manually using Weave and half framerate mode (which won't work for pulldown sources). This feature is being improved.


7. FAQ: Does tvtime support recording?

tvtime does not yet support recording or playback of recorded streams. If you are interested in helping with coding this feature, please contact the authors.


8. FAQ: Why does tvtime appear blue in screenshots?

tvtime outputs video into a video overlay surface, an area of memory outside of the framebuffer, using the XVIDEO X extension. As such, applications which take screenshots such as ksnapshot, gimp or xwd only see the colourkeyed window, and not output of tvtime.

We believe it is a design flaw or driver limitation on the X or video card hardware that one or the other cannot provide the image to screenshot applications. For this reason, the only known workaround for taking screenshots of tvtime along with the desktop is to use the screenshot feature inside tvtime, and cut-and-paste the output into a full desktop screen capture.


9. FAQ: Purple lines in video? How do I avoid macrovision?

If you are seeing purple lines or having problems with video signal quality from an external DVD player, VCR, or Laserdisc player, try disabling Macrovision in your bttv driver (if you have a bttv card). See http://www.colby.edu/personal/k/kjseptor/bttv.html for information on how to do that.


10. FAQ: Interference problems with soundcards

If you are experiencing a generally fuzzy picture, try moving your tv card one or two slots away from your soundcard (inside your pc). Interference from the soundcard can mess up some channels.


11. FAQ: Optimal settings for tvtime on TV output

Some people are interested in using tvtime even when their output itself a television. Usually this is in the context of setting up a home theatre PC system as in a PVR. Ideally for television output, no deinterlacing is required; the interlaced signal is sent to the output such that every top field in the input is mapped to a top field in the output.

Unfortunately, there is no standard TV output API under linux. The vesa framebuffer setup for TV output cannot tell us which field is currently being output. Similarily, some TV output setups under linux have it as a second head in X, but again, with no field information we cannot know how to supply it with interlaced content to ensure that fields are shown in the right order.

There are two possible solutions. I have been told that with the NVIDIA TV output drivers, when using XVIDEO, if you supply them with top-field-first frames, they will display the fields correctly. To experiment, try tvtime using the Weave deinterlacer, and select half framerate in TFF mode. This may give good results. The second option would be using a card with a TV output driver that gives field information. An example is the Matrox G400/G450/G550 driver in DirectFB. We are working on native support for TV output in this setting.


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