Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

Some very frequently asked questions about linuxtv-dvb

1. The signal seems to die a few seconds after tuning.

        It's not a bug, it's a feature. Because the frontends have
        significant power requirements (and hence get very hot), they
        are powered down if they are unused (i.e. if the frontend device
        is closed). The dvb-core.o module parameter "dvb_shutdown_timeout"
        allow you to change the timeout (default 5 seconds). Setting the
        timeout to 0 disables the timeout feature.

2. How can I watch TV?

        The driver distribution includes some simple utilities which
        are mainly intended for testing and to demonstrate how the
        DVB API works.

        Depending on whether you have a DVB-S, DVB-C or DVB-T card, use
        apps/szap/szap, czap or tzap. You must supply a channel list
        in ~/.[sct]zap/channels.conf. If you are lucky you can just copy
        one of the supplied channel lists, or you can create a new one
        by running apps/scan/scan. If you run scan on an unknown network
        you might have to supply some start data in apps/scan/initial.h.

        If you have a card with a built-in hardware MPEG-decoder the
        drivers create a video4linux device (/dev/v4l/video0) which
        you can use to watch TV with any v4l application. xawtv is known
        to work. Note that you cannot change channels with xawtv, you
        have to zap using [sct]zap. If you want a nice application for
        TV watching and record/playback, have a look at VDR.

        If your card does not have a hardware MPEG decoder you need
        a software MPEG decoder. Mplayer or xine are known to work.
        Newsflash: MythTV also has DVB support now.
        Note: Only very recent versions of Mplayer and xine can decode.
        MPEG2 transport streams (TS) directly. Then, run
        '[sct]zap channelname -r' in one xterm, and keep it running,
        and start 'mplayer - < /dev/dvb/adapter0/dvr0' or
        'xine stdin://mpeg2 < /dev/dvb/adapter0/dvr0' in a second xterm.
        That's all far from perfect, but it seems no one has written
        a nice DVB application which includes a builtin software MPEG
        decoder yet.

        Newsflash: Newest xine directly supports DVB. Just copy your
        channels.conf to ~/.xine and start 'xine dvb://', or select
        the DVB button in the xine GUI. Channel switching works using the
        numpad pgup/pgdown (NP9 / NP3) keys to scroll through the channel osd
        menu and pressing numpad-enter to switch to the selected channel.

        Note: Older versions of xine and mplayer understand MPEG program
        streams (PS) only, and can be used in conjunction with the
        ts2ps tool from the Metzler Brother's dvb-mpegtools package.

3. Which other DVB applications exist?

        http://www.cadsoft.de/people/kls/vdr/
                Klaus Schmidinger's Video Disk Recorder

        http://www.metzlerbros.org/dvb/
                Metzler Bros. DVB development; alternate drivers and
                DVB utilities, include dvb-mpegtools and tuxzap.

        http://sourceforge.net/projects/dvbtools/
                Dave Chapman's dvbtools package, including
                dvbstream and dvbtune

        http://www.linuxdvb.tv/
                Henning Holtschneider's site with many interesting
                links and docs

        http://www.dbox2.info/
                LinuxDVB on the dBox2

        http://www.tuxbox.org/
        http://cvs.tuxbox.org/
                the TuxBox CVS many interesting DVB applications and the dBox2
                DVB source

        http://sourceforge.net/projects/dvbsak/
                DVB Swiss Army Knife library and utilities

        http://www.nenie.org/misc/mpsys/
                MPSYS: a MPEG2 system library and tools

        http://mplayerhq.hu/
                mplayer

        http://xine.sourceforge.net/
        http://xinehq.de/
                xine

        http://www.mythtv.org/
                MythTV - analog TV PVR, but now with DVB support, too
                (with software MPEG decode)

        http://dvbsnoop.sourceforge.net/
                DVB sniffer program to monitor, analyze, debug, dump
                or view dvb/mpeg/dsm-cc/mhp stream information (TS,
                PES, SECTION)

4. Can't get a signal tuned correctly

        If you are using a Technotrend/Hauppauge DVB-C card *without* analog
        module, you might have to use module parameter adac=-1 (dvb-ttpci.o).

5. The dvb_net device doesn't give me any packets at all

        Run tcpdump on the dvb0_0 interface. This sets the interface
        into promiscous mode so it accepts any packets from the PID
        you have configured with the dvbnet utility. Check if there
        are any packets with the IP addr and MAC addr you have
        configured with ifconfig.

        If tcpdump doesn't give you any output, check the statistics
        which ifconfig outputs. (Note: If the MAC address is wrong,
        dvb_net won't get any input; thus you have to run tcpdump
        before checking the statistics.) If there are no packets at
        all then maybe the PID is wrong. If there are error packets,
        then either the PID is wrong or the stream does not conform to
        the MPE standard (EN 301 192, http://www.etsi.org/). You can
        use e.g. dvbsnoop for debugging.

6. The dvb_net device doesn't give me any multicast packets

        Check your routes if they include the multicast address range.
        Additionally make sure that "source validation by reversed path
        lookup" is disabled:
          $ "echo 0 > /proc/sys/net/ipv4/conf/dvb0/rp_filter"

7. What the hell are all those modules that need to be loaded?

        For a dvb-ttpci av7110 based full-featured card the following
        modules are loaded:

        - videodev: Video4Linux core module. This is the base module that
          gives you access to the "analog" tv picture of the av7110 mpeg2
          decoder.

        - v4l2-common: common functions for Video4Linux-2 drivers

        - v4l1-compat: backward compatibility layer for Video4Linux-1 legacy
          applications

        - dvb-core: DVB core module. This provides you with the
          /dev/dvb/adapter entries

        - saa7146: SAA7146 core driver. This is need to access any SAA7146
          based card in your system.

        - saa7146_vv: SAA7146 video and vbi functions. These are only needed
          for full-featured cards.

        - videobuf-dma-sg: capture helper module for the saa7146_vv driver. This
          one is responsible to handle capture buffers.

        - dvb-ttpci: The main driver for AV7110 based, full-featured
          DVB-S/C/T cards

eof