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1.. SPDX-License-Identifier: GPL-2.02 3FAQ4===5 6.. note::7 8 1. With Digital TV, a single physical channel may have different9 contents inside it. The specs call each one as a *service*.10 This is what a TV user would call "channel". So, in order to11 avoid confusion, we're calling *transponders* as the physical12 channel on this FAQ, and *services* for the logical channel.13 2. The LinuxTV community maintains some Wiki pages with contain14 a lot of information related to the media subsystem. If you15 don't find an answer for your needs here, it is likely that16 you'll be able to get something useful there. It is hosted17 at:18 19 https://www.linuxtv.org/wiki/20 21Some very frequently asked questions about Linux Digital TV support22 231. The signal seems to die a few seconds after tuning.24 25 It's not a bug, it's a feature. Because the frontends have26 significant power requirements (and hence get very hot), they27 are powered down if they are unused (i.e. if the frontend device28 is closed). The ``dvb-core`` module parameter ``dvb_shutdown_timeout``29 allow you to change the timeout (default 5 seconds). Setting the30 timeout to 0 disables the timeout feature.31 322. How can I watch TV?33 34 Together with the Linux Kernel, the Digital TV developers support35 some simple utilities which are mainly intended for testing36 and to demonstrate how the DVB API works. This is called DVB v537 tools and are grouped together with the ``v4l-utils`` git repository:38 39 https://git.linuxtv.org/v4l-utils.git/40 41 You can find more information at the LinuxTV wiki:42 43 https://www.linuxtv.org/wiki/index.php/DVBv5_Tools44 45 The first step is to get a list of services that are transmitted.46 47 This is done by using several existing tools. You can use48 for example the ``dvbv5-scan`` tool. You can find more information49 about it at:50 51 https://www.linuxtv.org/wiki/index.php/Dvbv5-scan52 53 There are some other applications like ``w_scan`` [#]_ that do a54 blind scan, trying hard to find all possible channels, but55 those consumes a large amount of time to run.56 57 .. [#] https://www.linuxtv.org/wiki/index.php/W_scan58 59 Also, some applications like ``kaffeine`` have their own code60 to scan for services. So, you don't need to use an external61 application to obtain such list.62 63 Most of such tools need a file containing a list of channel64 transponders available on your area. So, LinuxTV developers65 maintain tables of Digital TV channel transponders, receiving66 patches from the community to keep them updated.67 68 This list is hosted at:69 70 https://git.linuxtv.org/dtv-scan-tables.git71 72 And packaged on several distributions.73 74 Kaffeine has some blind scan support for some terrestrial standards.75 It also relies on DTV scan tables, although it contains a copy76 of it internally (and, if requested by the user, it will download77 newer versions of it).78 79 If you are lucky you can just use one of the supplied channel80 transponders. If not, you may need to seek for such info at81 the Internet and create a new file. There are several sites with82 contains physical channel lists. For cable and satellite, usually83 knowing how to tune into a single channel is enough for the84 scanning tool to identify the other channels. On some places,85 this could also work for terrestrial transmissions.86 87 Once you have a transponders list, you need to generate a services88 list with a tool like ``dvbv5-scan``.89 90 Almost all modern Digital TV cards don't have built-in hardware91 MPEG-decoders. So, it is up to the application to get a MPEG-TS92 stream provided by the board, split it into audio, video and other93 data and decode.94 953. Which Digital TV applications exist?96 97 Several media player applications are capable of tuning into98 digital TV channels, including Kaffeine, Vlc, mplayer and MythTV.99 100 Kaffeine aims to be very user-friendly, and it is maintained101 by one of the Kernel driver developers.102 103 A comprehensive list of those and other apps can be found at:104 105 https://www.linuxtv.org/wiki/index.php/TV_Related_Software106 107 Some of the most popular ones are linked below:108 109 https://kde.org/applications/multimedia/org.kde.kaffeine110 KDE media player, focused on Digital TV support111 112 https://www.linuxtv.org/vdrwiki/index.php/Main_Page113 Klaus Schmidinger's Video Disk Recorder114 115 https://linuxtv.org/downloads and https://git.linuxtv.org/116 Digital TV and other media-related applications and117 Kernel drivers. The ``v4l-utils`` package there contains118 several swiss knife tools for using with Digital TV.119 120 http://sourceforge.net/projects/dvbtools/121 Dave Chapman's dvbtools package, including122 dvbstream and dvbtune123 124 http://www.dbox2.info/125 LinuxDVB on the dBox2126 127 http://www.tuxbox.org/128 the TuxBox CVS many interesting DVB applications and the dBox2129 DVB source130 131 http://www.nenie.org/misc/mpsys/132 MPSYS: a MPEG2 system library and tools133 134 https://www.videolan.org/vlc/index.pt.html135 Vlc136 137 http://mplayerhq.hu/138 MPlayer139 140 http://xine.sourceforge.net/ and http://xinehq.de/141 Xine142 143 http://www.mythtv.org/144 MythTV - analog TV and digital TV PVR145 146 http://dvbsnoop.sourceforge.net/147 DVB sniffer program to monitor, analyze, debug, dump148 or view dvb/mpeg/dsm-cc/mhp stream information (TS,149 PES, SECTION)150 1514. Can't get a signal tuned correctly152 153 That could be due to a lot of problems. On my personal experience,154 usually TV cards need stronger signals than TV sets, and are more155 sensitive to noise. So, perhaps you just need a better antenna or156 cabling. Yet, it could also be some hardware or driver issue.157 158 For example, if you are using a Technotrend/Hauppauge DVB-C card159 *without* analog module, you might have to use module parameter160 adac=-1 (dvb-ttpci.o).161 162 Please see the FAQ page at linuxtv.org, as it could contain some163 valuable information:164 165 https://www.linuxtv.org/wiki/index.php/FAQ_%26_Troubleshooting166 167 If that doesn't work, check at the linux-media ML archives, to168 see if someone else had a similar problem with your hardware169 and/or digital TV service provider:170 171 https://lore.kernel.org/linux-media/172 173 If none of this works, you can try sending an e-mail to the174 linux-media ML and see if someone else could shed some light.175 The e-mail is linux-media AT vger.kernel.org.176 1775. The dvb_net device doesn't give me any packets at all178 179 Run ``tcpdump`` on the ``dvb0_0`` interface. This sets the interface180 into promiscuous mode so it accepts any packets from the PID181 you have configured with the ``dvbnet`` utility. Check if there182 are any packets with the IP addr and MAC addr you have183 configured with ``ifconfig`` or with ``ip addr``.184 185 If ``tcpdump`` doesn't give you any output, check the statistics186 which ``ifconfig`` or ``netstat -ni`` outputs. (Note: If the MAC187 address is wrong, ``dvb_net`` won't get any input; thus you have to188 run ``tcpdump`` before checking the statistics.) If there are no189 packets at all then maybe the PID is wrong. If there are error packets,190 then either the PID is wrong or the stream does not conform to191 the MPE standard (EN 301 192, http://www.etsi.org/). You can192 use e.g. ``dvbsnoop`` for debugging.193 1946. The ``dvb_net`` device doesn't give me any multicast packets195 196 Check your routes if they include the multicast address range.197 Additionally make sure that "source validation by reversed path198 lookup" is disabled::199 200 $ "echo 0 > /proc/sys/net/ipv4/conf/dvb0/rp_filter"201 2027. What are all those modules that need to be loaded?203 204 In order to make it more flexible and support different hardware205 combinations, the media subsystem is written on a modular way.206 207 So, besides the Digital TV hardware module for the main chipset,208 it also needs to load a frontend driver, plus the Digital TV209 core. If the board also has remote controller, it will also210 need the remote controller core and the remote controller tables.211 The same happens if the board has support for analog TV: the212 core support for video4linux need to be loaded.213 214 The actual module names are Linux-kernel version specific, as,215 from time to time, things change, in order to make the media216 support more flexible.217