217 строки
7.9 KiB
ReStructuredText
217 строки
7.9 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
FAQ
|
|
===
|
|
|
|
.. note::
|
|
|
|
1. With Digital TV, a single physical channel may have different
|
|
contents inside it. The specs call each one as a *service*.
|
|
This is what a TV user would call "channel". So, in order to
|
|
avoid confusion, we're calling *transponders* as the physical
|
|
channel on this FAQ, and *services* for the logical channel.
|
|
2. The LinuxTV community maintains some Wiki pages with contain
|
|
a lot of information related to the media subsystem. If you
|
|
don't find an answer for your needs here, it is likely that
|
|
you'll be able to get something useful there. It is hosted
|
|
at:
|
|
|
|
https://www.linuxtv.org/wiki/
|
|
|
|
Some very frequently asked questions about Linux Digital TV support
|
|
|
|
1. The signal seems to die a few seconds after tuning.
|
|
|
|
It's not a bug, it's a feature. Because the frontends have
|
|
significant power requirements (and hence get very hot), they
|
|
are powered down if they are unused (i.e. if the frontend device
|
|
is closed). The ``dvb-core`` module parameter ``dvb_shutdown_timeout``
|
|
allow you to change the timeout (default 5 seconds). Setting the
|
|
timeout to 0 disables the timeout feature.
|
|
|
|
2. How can I watch TV?
|
|
|
|
Together with the Linux Kernel, the Digital TV developers support
|
|
some simple utilities which are mainly intended for testing
|
|
and to demonstrate how the DVB API works. This is called DVB v5
|
|
tools and are grouped together with the ``v4l-utils`` git repository:
|
|
|
|
https://git.linuxtv.org/v4l-utils.git/
|
|
|
|
You can find more information at the LinuxTV wiki:
|
|
|
|
https://www.linuxtv.org/wiki/index.php/DVBv5_Tools
|
|
|
|
The first step is to get a list of services that are transmitted.
|
|
|
|
This is done by using several existing tools. You can use
|
|
for example the ``dvbv5-scan`` tool. You can find more information
|
|
about it at:
|
|
|
|
https://www.linuxtv.org/wiki/index.php/Dvbv5-scan
|
|
|
|
There are some other applications like ``w_scan`` [#]_ that do a
|
|
blind scan, trying hard to find all possible channels, but
|
|
those consumes a large amount of time to run.
|
|
|
|
.. [#] https://www.linuxtv.org/wiki/index.php/W_scan
|
|
|
|
Also, some applications like ``kaffeine`` have their own code
|
|
to scan for services. So, you don't need to use an external
|
|
application to obtain such list.
|
|
|
|
Most of such tools need a file containing a list of channel
|
|
transponders available on your area. So, LinuxTV developers
|
|
maintain tables of Digital TV channel transponders, receiving
|
|
patches from the community to keep them updated.
|
|
|
|
This list is hosted at:
|
|
|
|
https://git.linuxtv.org/dtv-scan-tables.git
|
|
|
|
And packaged on several distributions.
|
|
|
|
Kaffeine has some blind scan support for some terrestrial standards.
|
|
It also relies on DTV scan tables, although it contains a copy
|
|
of it internally (and, if requested by the user, it will download
|
|
newer versions of it).
|
|
|
|
If you are lucky you can just use one of the supplied channel
|
|
transponders. If not, you may need to seek for such info at
|
|
the Internet and create a new file. There are several sites with
|
|
contains physical channel lists. For cable and satellite, usually
|
|
knowing how to tune into a single channel is enough for the
|
|
scanning tool to identify the other channels. On some places,
|
|
this could also work for terrestrial transmissions.
|
|
|
|
Once you have a transponders list, you need to generate a services
|
|
list with a tool like ``dvbv5-scan``.
|
|
|
|
Almost all modern Digital TV cards don't have built-in hardware
|
|
MPEG-decoders. So, it is up to the application to get a MPEG-TS
|
|
stream provided by the board, split it into audio, video and other
|
|
data and decode.
|
|
|
|
3. Which Digital TV applications exist?
|
|
|
|
Several media player applications are capable of tuning into
|
|
digital TV channels, including Kaffeine, Vlc, mplayer and MythTV.
|
|
|
|
Kaffeine aims to be very user-friendly, and it is maintained
|
|
by one of the Kernel driver developers.
|
|
|
|
A comprehensive list of those and other apps can be found at:
|
|
|
|
https://www.linuxtv.org/wiki/index.php/TV_Related_Software
|
|
|
|
Some of the most popular ones are linked below:
|
|
|
|
https://kde.org/applications/multimedia/org.kde.kaffeine
|
|
KDE media player, focused on Digital TV support
|
|
|
|
https://www.linuxtv.org/vdrwiki/index.php/Main_Page
|
|
Klaus Schmidinger's Video Disk Recorder
|
|
|
|
https://linuxtv.org/downloads and https://git.linuxtv.org/
|
|
Digital TV and other media-related applications and
|
|
Kernel drivers. The ``v4l-utils`` package there contains
|
|
several swiss knife tools for using with Digital TV.
|
|
|
|
http://sourceforge.net/projects/dvbtools/
|
|
Dave Chapman's dvbtools package, including
|
|
dvbstream and dvbtune
|
|
|
|
http://www.dbox2.info/
|
|
LinuxDVB on the dBox2
|
|
|
|
http://www.tuxbox.org/
|
|
the TuxBox CVS many interesting DVB applications and the dBox2
|
|
DVB source
|
|
|
|
http://www.nenie.org/misc/mpsys/
|
|
MPSYS: a MPEG2 system library and tools
|
|
|
|
https://www.videolan.org/vlc/index.pt.html
|
|
Vlc
|
|
|
|
http://mplayerhq.hu/
|
|
MPlayer
|
|
|
|
http://xine.sourceforge.net/ and http://xinehq.de/
|
|
Xine
|
|
|
|
http://www.mythtv.org/
|
|
MythTV - analog TV and digital TV PVR
|
|
|
|
http://dvbsnoop.sourceforge.net/
|
|
DVB sniffer program to monitor, analyze, debug, dump
|
|
or view dvb/mpeg/dsm-cc/mhp stream information (TS,
|
|
PES, SECTION)
|
|
|
|
4. Can't get a signal tuned correctly
|
|
|
|
That could be due to a lot of problems. On my personal experience,
|
|
usually TV cards need stronger signals than TV sets, and are more
|
|
sensitive to noise. So, perhaps you just need a better antenna or
|
|
cabling. Yet, it could also be some hardware or driver issue.
|
|
|
|
For example, if you are using a Technotrend/Hauppauge DVB-C card
|
|
*without* analog module, you might have to use module parameter
|
|
adac=-1 (dvb-ttpci.o).
|
|
|
|
Please see the FAQ page at linuxtv.org, as it could contain some
|
|
valuable information:
|
|
|
|
https://www.linuxtv.org/wiki/index.php/FAQ_%26_Troubleshooting
|
|
|
|
If that doesn't work, check at the linux-media ML archives, to
|
|
see if someone else had a similar problem with your hardware
|
|
and/or digital TV service provider:
|
|
|
|
https://lore.kernel.org/linux-media/
|
|
|
|
If none of this works, you can try sending an e-mail to the
|
|
linux-media ML and see if someone else could shed some light.
|
|
The e-mail is linux-media AT vger.kernel.org.
|
|
|
|
5. The dvb_net device doesn't give me any packets at all
|
|
|
|
Run ``tcpdump`` on the ``dvb0_0`` interface. This sets the interface
|
|
into promiscuous mode so it accepts any packets from the PID
|
|
you have configured with the ``dvbnet`` utility. Check if there
|
|
are any packets with the IP addr and MAC addr you have
|
|
configured with ``ifconfig`` or with ``ip addr``.
|
|
|
|
If ``tcpdump`` doesn't give you any output, check the statistics
|
|
which ``ifconfig`` or ``netstat -ni`` outputs. (Note: If the MAC
|
|
address is wrong, ``dvb_net`` won't get any input; thus you have to
|
|
run ``tcpdump`` before checking the statistics.) If there are no
|
|
packets at all then maybe the PID is wrong. If there are error packets,
|
|
then either the PID is wrong or the stream does not conform to
|
|
the MPE standard (EN 301 192, http://www.etsi.org/). You can
|
|
use e.g. ``dvbsnoop`` for debugging.
|
|
|
|
6. The ``dvb_net`` device doesn't give me any multicast packets
|
|
|
|
Check your routes if they include the multicast address range.
|
|
Additionally make sure that "source validation by reversed path
|
|
lookup" is disabled::
|
|
|
|
$ "echo 0 > /proc/sys/net/ipv4/conf/dvb0/rp_filter"
|
|
|
|
7. What are all those modules that need to be loaded?
|
|
|
|
In order to make it more flexible and support different hardware
|
|
combinations, the media subsystem is written on a modular way.
|
|
|
|
So, besides the Digital TV hardware module for the main chipset,
|
|
it also needs to load a frontend driver, plus the Digital TV
|
|
core. If the board also has remote controller, it will also
|
|
need the remote controller core and the remote controller tables.
|
|
The same happens if the board has support for analog TV: the
|
|
core support for video4linux need to be loaded.
|
|
|
|
The actual module names are Linux-kernel version specific, as,
|
|
from time to time, things change, in order to make the media
|
|
support more flexible.
|