Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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+.. 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.