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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