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Based on kernel version 3.16. Page generated on 2014-08-06 21:39 EST.

1	Some very frequently asked questions about linuxtv-dvb
2	
3	1. 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	
12	2. 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	
54	3. 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	
101	4. 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	
106	5. 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	
123	6. 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	
130	7. 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	
159	eof
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