Documentation/dvb/faq.txt

   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