Root/Documentation/dvb/faq.txt

1Some very frequently asked questions about linuxtv-dvb
2
31. The signal seems to die a few seconds after tuning.
4
5    It's not a bug, it's a feature. Because the frontends have
6    significant power requirements (and hence get very hot), they
7    are powered down if they are unused (i.e. if the frontend device
8    is closed). The dvb-core.o module parameter "dvb_shutdown_timeout"
9    allow you to change the timeout (default 5 seconds). Setting the
10    timeout to 0 disables the timeout feature.
11
122. How can I watch TV?
13
14    The driver distribution includes some simple utilities which
15    are mainly intended for testing and to demonstrate how the
16    DVB API works.
17
18    Depending on whether you have a DVB-S, DVB-C or DVB-T card, use
19    apps/szap/szap, czap or tzap. You must supply a channel list
20    in ~/.[sct]zap/channels.conf. If you are lucky you can just copy
21    one of the supplied channel lists, or you can create a new one
22    by running apps/scan/scan. If you run scan on an unknown network
23    you might have to supply some start data in apps/scan/initial.h.
24
25    If you have a card with a built-in hardware MPEG-decoder the
26    drivers create a video4linux device (/dev/v4l/video0) which
27    you can use to watch TV with any v4l application. xawtv is known
28    to work. Note that you cannot change channels with xawtv, you
29    have to zap using [sct]zap. If you want a nice application for
30    TV watching and record/playback, have a look at VDR.
31
32    If your card does not have a hardware MPEG decoder you need
33    a software MPEG decoder. Mplayer or xine are known to work.
34    Newsflash: MythTV also has DVB support now.
35    Note: Only very recent versions of Mplayer and xine can decode.
36    MPEG2 transport streams (TS) directly. Then, run
37    '[sct]zap channelname -r' in one xterm, and keep it running,
38    and start 'mplayer - < /dev/dvb/adapter0/dvr0' or
39    'xine stdin://mpeg2 < /dev/dvb/adapter0/dvr0' in a second xterm.
40    That's all far from perfect, but it seems no one has written
41    a nice DVB application which includes a builtin software MPEG
42    decoder yet.
43
44    Newsflash: Newest xine directly supports DVB. Just copy your
45    channels.conf to ~/.xine and start 'xine dvb://', or select
46    the DVB button in the xine GUI. Channel switching works using the
47    numpad pgup/pgdown (NP9 / NP3) keys to scroll through the channel osd
48    menu and pressing numpad-enter to switch to the selected channel.
49
50    Note: Older versions of xine and mplayer understand MPEG program
51    streams (PS) only, and can be used in conjunction with the
52    ts2ps tool from the Metzler Brother's dvb-mpegtools package.
53
543. Which other DVB applications exist?
55
56    http://www.cadsoft.de/people/kls/vdr/
57        Klaus Schmidinger's Video Disk Recorder
58
59    http://www.metzlerbros.org/dvb/
60        Metzler Bros. DVB development; alternate drivers and
61        DVB utilities, include dvb-mpegtools and tuxzap.
62
63    http://sourceforge.net/projects/dvbtools/
64        Dave Chapman's dvbtools package, including
65        dvbstream and dvbtune
66
67    http://www.linuxdvb.tv/
68        Henning Holtschneider's site with many interesting
69        links and docs
70
71    http://www.dbox2.info/
72        LinuxDVB on the dBox2
73
74    http://www.tuxbox.org/
75    http://cvs.tuxbox.org/
76        the TuxBox CVS many interesting DVB applications and the dBox2
77        DVB source
78
79    http://www.linuxtv.org/downloads/
80        DVB Swiss Army Knife library and utilities
81
82    http://www.nenie.org/misc/mpsys/
83        MPSYS: a MPEG2 system library and tools
84
85    http://mplayerhq.hu/
86        mplayer
87
88    http://xine.sourceforge.net/
89    http://xinehq.de/
90        xine
91
92    http://www.mythtv.org/
93        MythTV - analog TV PVR, but now with DVB support, too
94        (with software MPEG decode)
95
96    http://dvbsnoop.sourceforge.net/
97        DVB sniffer program to monitor, analyze, debug, dump
98        or view dvb/mpeg/dsm-cc/mhp stream information (TS,
99        PES, SECTION)
100
1014. Can't get a signal tuned correctly
102
103    If you are using a Technotrend/Hauppauge DVB-C card *without* analog
104    module, you might have to use module parameter adac=-1 (dvb-ttpci.o).
105
1065. The dvb_net device doesn't give me any packets at all
107
108    Run tcpdump on the dvb0_0 interface. This sets the interface
109    into promiscuous mode so it accepts any packets from the PID
110    you have configured with the dvbnet utility. Check if there
111    are any packets with the IP addr and MAC addr you have
112    configured with ifconfig.
113
114    If tcpdump doesn't give you any output, check the statistics
115    which ifconfig outputs. (Note: If the MAC address is wrong,
116    dvb_net won't get any input; thus you have to run tcpdump
117    before checking the statistics.) If there are no packets at
118    all then maybe the PID is wrong. If there are error packets,
119    then either the PID is wrong or the stream does not conform to
120    the MPE standard (EN 301 192, http://www.etsi.org/). You can
121    use e.g. dvbsnoop for debugging.
122
1236. The dvb_net device doesn't give me any multicast packets
124
125    Check your routes if they include the multicast address range.
126    Additionally make sure that "source validation by reversed path
127    lookup" is disabled:
128      $ "echo 0 > /proc/sys/net/ipv4/conf/dvb0/rp_filter"
129
1307. What the hell are all those modules that need to be loaded?
131
132    For a dvb-ttpci av7110 based full-featured card the following
133    modules are loaded:
134
135    - videodev: Video4Linux core module. This is the base module that
136      gives you access to the "analog" tv picture of the av7110 mpeg2
137      decoder.
138
139    - v4l2-common: common functions for Video4Linux-2 drivers
140
141    - v4l1-compat: backward compatibility layer for Video4Linux-1 legacy
142      applications
143
144    - dvb-core: DVB core module. This provides you with the
145      /dev/dvb/adapter entries
146
147    - saa7146: SAA7146 core driver. This is need to access any SAA7146
148      based card in your system.
149
150    - saa7146_vv: SAA7146 video and vbi functions. These are only needed
151      for full-featured cards.
152
153    - videobuf-dma-sg: capture helper module for the saa7146_vv driver. This
154      one is responsible to handle capture buffers.
155
156    - dvb-ttpci: The main driver for AV7110 based, full-featured
157      DVB-S/C/T cards
158
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