Documentation/admin-guide/media/faq.rst

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Documentation/admin-guide/media/faq.rst
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Support Tooling And Documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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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

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