Frequently Asked Questions
- Linux specific
- Windows specific
- Tips and Tricks
- Q: How do I keep nxtvepg from changing the channel while I'm watching TV?
This is a problem which should only occur with v4l2 drivers (2nd generation of the video4linux driver API), i.e. saa7134 and cx8800 - which only support v4l2 - or bttv version 9.
Explanation: The reason is that v4l2 allows multiple opens on the /dev/video device, hence the old v4l1 trick of switching channels through the video device (which would only succeed if no TV app had already opened it) does not work anymore. The problem was already addressed early 2003 by designing a new driver interface which allows background data harvesting applications to lower their priority beneath that of interactive applications like TV watching. You can check if your kernel or video4linux module supports that feature by looking for ioctl VIDIOC_S_PRIORITY in videodev2.h. However it took quite a while until the new feature was merged into the main kernel line.
Solution: Upgrade to nxtvepg 2.7.0 and linux kernel 2.6.2 (e.g. from kernel.org or check your distribution's upgrade options). Experienced users may alternatively upgrade video4linux by downloading the latest module releases or snapshots from bytesex.org. Caution: this may require to patch your kernel, check out the patches section at the bytesex.org site.
- Q: How do I tell nxtvepg to switch channels via /dev/video1 while my VBI device is /dev/vbi0?
The problem occurs when your first video device does not support VBI. Subsequent video devices will have mismatching video and vbi device indices because the drivers usually allocate the first free device index.
nxtvepg uses /dev/videoN both for the device scan (in the TV card input configuration dialog) and to switch TV channels. However for Nextview EPG acquisition /dev/vbiN is used. nxtvepg will only work properly if video and vbi devices which refer to the hardware which you want to use for acquisition have the same index N. There is no way to change that, however you can avoid the problem as explained below.
Solution: Force the driver to assign device index #1 to the VBI device. This is possible for video4linux drivers by using modprobe parameters in /etc/modules.conf, e.g. for bttv:
options bttv video_nr=1 vbi_nr=1
- Q: My TV card does not work. Help?
Unfortunately it's not possible to provide help for a question like this one, because it fails to provide any context. Remember the person(s) who you're asking are doing this on a voluntary basis in their spare time, so you should not put the additional burden onto them to guess what you might have been referring to with your question. Also consider that any time spent on support cannot be used to implement or improve features.
The minimum information you should provide is
- Your operating system, including version (e.g. "Windows XP")
- Your TV card brand and model number
- What did you already try to make the card work. You can refer to the description in Getting Started
- If there are any error messages displayed by nxtvepg, quote them exactly as printed on-screen.
- If there are no error messages, please explain what exactly "does not work", e.g. is your card not auto-detected, does the EPG provider scan find no channels or no providers, or is a provider found but reception does not work etc.
Important: You can save yourself a lot of time if you try to find out which model and tuner setting your card requires if you use DScaler (make sure to use a version from the alpha branch, e.g. 4.19) because it's so much easier when you see a TV image. If your card can't be made to work with DScaler (excluding WDM sources, see below) it won't work with nxtvepg either.
- Q: Can I use my AGP card or USB box with nxtvepg?
Under windows no, you can't. Only PCI cards are supported. See also next question.
- Q: Can I use my card's WDM drivers with nxtvepg?
As of writing this work on this area is underway, but there probably won't be a release until late 2005 (current planning, may still change)
- Q: Why does my "CX23881" based card not work although it's even auto-detected?
With cards based on the Conexant CX23881 (also known as Bt881) capture chip there are still unsolved problems with interference between the dsdrv and the vendor's WDM drivers. These WDM drivers are known to access the TV card even while no application is using them. Note: You can verify that this is the cause of acquisition problems by de-installing the WDM drivers, reboot and then try nxtvepg again (note nxtvepg doesn't require any vendor supplied drivers.)
Solution: none yet. As of nxtvepg 2.7.0 there's an option in the TV card input configuration dialog which allows to stop a vendor's WDM driver for the same card. However this is still experimental. Feel free to try it, but be prepared that you have to manually re-enable the WDM driver via the service control center in case nxtvepg fails to re-enable it.
- Q: Why can't I run nxtvepg in parallel to my TV application?
This problem occurs because nxtvepg accesses the TV card hardware directly, but only one application can control the hardware at the same time. Warning: Hardware access conflicts may crash your system, so you should take care to avoid such conflicts. If you mistakenly create such a conflict, immediately quit both applications; especially do not attempt to re-start capturing in either of them.
Solution: If you want to run nxtvepg in parallel to a TV app you only have the option to either use a supported TV application or to disable Nextview data acquisition while running the TV app. The latter can be done either at start time by adding the -noacq option on the command line or at run time by unchecking Enable acquisition in the Control menu.
- Q: When will TV application X be supported?
nxtvepg already offers multiple ways for TV applications to interact with it, hence it's generally up to the TV application's authors to show some interest in cooperation. In other words: first make the TV app's author interested.
Also check out the list of already supported applications
- Q: How do I catch EPG providers which aren't found by the scan?
Fist make sure by reading the provider list that you really can receive the network where the provider transmits and that it's still active. Unfortunately there are many possible causes which could make the provider scan fail, so there's also different solutions:
- Some networks only transmit part of the day (e.g. TV5) In this case you only can wait. Also some providers have transmission gaps sometimes for technical reasons. So be patient.
- Load a TV application's channel table, for example from K!TV or xawtv (see checkbuttons at the bottom of the provider scan dialog window; note you need to configure TV app. interaction first via the Configure menu) and enable "slow" mode.
- Tune the network manually. On UNIX, just fire up xawtv or some other
TV application and tune in the respective TV channel or frequency.
nxtvepg will automatically try to find a provider on this channel
in the background. You can check Acquisition statistics
(see control menu) for the progress; see also next question for
info how to read the statistics.
On Windows it works basically the same, but you have to use a TV app. which supports Nextview acquisition during TV watching. As of writing this it's only K!TV.
- Last but not least, if it's not just one, but all provider which are missing, your card configuration may not be correct or signal quality too bad. See manual chapter Getting Started.
- Q: Nextview EPG acquisition suddenly doesn't work anymore. Is provider X dead?
Please check the provider list. If your provider is listed as being active there, it's probably not dead.
As a general rule: try to remember what you changed since nxtvepg last worked, and temporarily undo it. This includes software installation or upgrades, hardware configuration changes (new PCI cards etc.) or changes in cabling (esp. TV antenna cables)
If this doesn't help, try an EPG provider scan. If the scan doesn't show any channels check your antenna cable again and check your TV image quality and teletext reception (e.g. for missing characters or lines.) Note that even if your TV image still looks sort-of OK, some kinds of "systematic" errors will make Nextview EPG reception impossible. As of 2.7.0 decoding statistics have been added to nxtvepg's "acquisition statistics" (Control menu). You can use them to analyze the root of your reception problems:
- Check acquisition status: if it says "passive" nxtvepg failed to switch to the provider's channel. If the reason is "no tuner" you have selected an external source as input instead of the internal tuner, so you must make sure you have tuned a provider channel at your external source (e.g. SAT receiver); if the reason is "frequency missing" re-run a provider scan; if the reason is "device busy" stop any other video or teletext applications so that nxtvepg can tune a provider channel.
- Check VPS/PDC label and network name: should display your provider's network name. If not, re-run the EPG provider scan and check if your provider's network is identified at all. If not, your reception may be generally too bad.
- Check the teletext data rate: should be at least 150 kBaud for most providers (up to 230 kBaud for some.) If it's much less your reception is too weak to receive Nextview EPG.
- Check if EPG data is detected: the EPG page rate should be 1 to 1.5 per second. If you don't get any pages although teletext data rate is OK, your provider may have temporarily suspended transmission. Try again later.
- Check if "AI blocks" are received: usually one should be received every 10 seconds. If you do get a good EPG page rate but still no AI blocks, there may be "systematic" packet loss, e.g. the first or last line on every page missing. Since AI blocks are very large and hence span many teletext packets, such losses can completely prohibit Nextview EPG reception. If your teletext reception is otherwise OK, these losses may be caused by driver problems or sometimes by hardware problems (e.g. "overload" on a PCI bus, or interrupt problems.) Check that you have the latest drivers, or try to move the TV card to a different PCI slot.
Note if the statistics are reset every couple seconds, i.e. the acquisition runtime restarts at zero, this is just another indication of decoding errors (i.e. nxtvepg falsely assumes there's been a channel change when there are too many changes in teletext headers.)
If that's to complicated, feel free to ask in the forum, but make sure to include an copy of the statistics output and describe what you already checked or tried to make acquisition work.
- Q: All times are wrong by one or two hours. How do I fix that?
Dates and times in Nextview EPG are transmitted by the content providers in UTC (Universal Coordinated Time also known as Greenwhich Mean Time aka GMT.) Hence to display them correctly, dates and times need to be converted into your local time zone, which will only work correctly if you configure your PC's time zone and daylight saving time (i.e. summer/winter time) settings. Especially after daylight saving time changes you should not only change your wall clock time, but also make sure your system's daylight saving time and/or time zone setting have been adapted.
nxtvepg also evaluates environment variable TZ, which allows to override the system's time zone setting. Usually this variable should not be defined, unless you know what you're doing.
Tips and Tricks
- Tip: Using Tages-Tipp and Movie-Star categories provided by FAST-TV on Kabel1 in Germany
When you select provider Kabel1 and open the Navigate menu (on Windows this is a sub-menu in the Filter menu) you'll find two entries called Tages-Tipp and Movie-Star which are editoral ratings by content provider FAST-TV.
You can copy these navigation entries into a filter shortcut simply by selecting them in the menu and then calling Add shortcut in the shortcuts menu. You may want to remove the start time filter (e.g. "today") beforehand by de-selecting this filter in Filter->Start time... Afterwards you can use these shortcuts even for a merged database (where you don't have a Navigate menu) You can also use them in the Attribute composition configuration dialog to mark the respective programmes (e.g. mark highlights by adding a small yellow dot and movie highlights with by a small red dot, like in this screenshot)
Note this provider also makes extensive use of sorting criteria, but you have to figure out for yourself which categories they are meant to represent.
- Tip: Restricting XMLTV export
To reduce the number of networks in exported XMLTV files, create a merged database and remove unwanted networks with the Network selection configuration dialog. You can also remove unnecessary categories (e.g. themes) by using the Configure sub-menu inside the merge dialog window. For example choose entry Themes in said menu, then in the small dialog which pops up remove all providers from the right list and press OK.
If you don't want to override your merge configuration when you browse programmes inside nxtvepg, you can use a different nxtvepg.ini or .nxtvepgrc file by using the -rcfile name option on the command line when starting nxtvepg.
- Tip: Air times restriction
For networks which you cannot receive the entire day (e.g. because several networks share the same channel like Arte and France 5), you can configure a restricted air time in the network selection configuration dialog, so that programmes which you cannot receive are automatically excluded from the listing.
- Tip: Changing colors and fonts
There's no configuration dialog to change colors or fonts. Instead these options are determined from a resource file (this is a concept of the UNIX X Window system) which needs to be edited by hand. Refer to manual section Files, section .Xdefaults for details.
- Tip: Sharing databases and configuration between Windows and Linux
If you dual-boot your PC you'll probably want to use the same databases under both operating systems, to avoid having to load everything twice. By default nxtvepg stores the programme databases at different places and with different file names under UNIX and Windows, however since nxtvepg version 0.2.7 it's possible to load data which was acquired under the respective other OS. Just use the -dbdir path command line option to point nxtvepg at the right directory. You can share your nxtvepg.ini aka .nxtvepgrc file the same way by using the -rcfile path command line option.
Since you cannot easily mount a UNIX filesystem under Windows it's recommended to use a Windows (FAT, FAT32 or network share) filesystem as shared directory. Note you need read and write access to that directory, unless you're using network acquisition mode only.
- Tip: How to print programme descriptions
nxtvepg does not support sending listings to a printer, however you can export single programmes or entire lists into a HTML file and then load the document into a web browser and print it from there. For details refer to manual section Export as HTML.
If this page didn't answer your question, please check the Discussion forum: if it's not answered in any of the latest posts, feel free to ask your question there.