[mythtv] DVB scan and satcodx lists

Marcus Metzler mocm at mocm.de
Tue Nov 16 20:12:55 UTC 2004

>>>>> "Taylor" == Taylor Jacob <rtjacob at earthlink.net> writes:

    >> I just tried the DVB setup of mythtv with the latest patch and
    >> apart from waiting for the CAM which does not exist the channel
    >> scan seems to work. It is a little slow, though.

    Taylor> Glad to hear that.. Also nice coming from someone whos
    Taylor> name is plastered all over linux dvb related things as
    Taylor> well..

    >> Since I decided to start working with mythtv now I would like
    >> to help with the DVB development. So my question is, if it has
    >> been considered to use transponder lists from satcodx to help
    >> with the DVB-S channel scans. The NIT scan may be fine for
    >> DVB-T or DVB-C where you only have a few channels compared to
    >> DVB-S, but with 4 satellites to scan that is a little slow and
    >> NITs are not aways complete.

    Taylor> I personally am not a fan of the SatCoDX lists.. In North
    Taylor> America at least they don't seem to always be right, and
    Taylor> its also not very easy to just get a list of Transponders.
    Taylor> On the other hand John and I had talked about using the
    Taylor> "Seeding" files that dvbscan uses to populate a
    Taylor> transponder list.

    Taylor> I haven't seen the NITs be incomplete very often.  I am
    Taylor> aware that some of the satellites in Germany don't send a
    Taylor> complete NIT for the satellite, but only for the
    Taylor> transponders that they operate on, which means that you
    Taylor> need to tune to a few different transponders to get a
    Taylor> complete scan of the Satellite (I can see this being a
    Taylor> pain in the arse).

    >> So I would like to be able to feed mythtv lists from satcodx or
    >> libdvb or any other scanning program.

    Taylor> As above I was thinking libdvb might be nicer, but one
    Taylor> advantage to satcodx that libdvb won't offer is flaging
    Taylor> transponders as feed transponders.  In the long term I
    Taylor> wanted to setup myth to search a list of transponders
    Taylor> marked as "feed" whenever it wasn't pre-occupied recording
    Taylor> and store all of these shows in a "Feed" group..  Which
    Taylor> using SatCoDX might faciliate this much easier than
    Taylor> libdvb.

I usually use the satcodx lists with satscan (from libdvb) which gives
me a libdvb dvbrc file. Maybe I should start with changing libdvb to
input some more formats and make an output to feed mythtv. This way I
could also include something to mark feeds. I am not sure, can I feed
a DVB list directly into the database? What files should I look at to
see how to do that? 

    >> If noone is working on that, I would be willing to start with
    >> that and appreciate any suggestions.

    Taylor> That would be good.  Another type of scan that John and I
    Taylor> had discussed in the past was for DVB-T/C checking every
    Taylor> frequency combination that is possible for a lock, so you
    Taylor> could do a completely blind scan if you told myth what
    Taylor> country you were in.. This type of scan would also be how
    Taylor> you would have to do ATSC scanning.. This of course will

That may be the only alternative, if yu don't have a list from
somewhere else.

    Taylor> become more of a big deal to me if the Dvico Fusion3 Gold
    Taylor> card ever gets support under linux-dvb since I am not a
    Taylor> far of the pchdtv drivers..  Of course this only applies
    Taylor> to those of us in North America and South Korea..

    >> I can also help with other problems you may have with DVB. I
    >> work or worked on several DVB card drivers and wrote the first
    >> application examples for the DVB API (like libdvb and
    >> dvb-mpegtools).

    Taylor> One major thing I would love to see added to the linuxdvb
    Taylor> drivers is the ATSC CRC checks.  I have done some testing
    Taylor> with the ATSC feeds over DVB-S I can get in North America
    Taylor> and I just ignore the CRC for now, and it realy ought to
    Taylor> be in the linux-dvb drivers at some point.. I am not sure
    Taylor> how you would tell the drivers which CRC routine to use
    Taylor> since the PAT and PMT in ATSC use the MPEGTS CRC, but the
    Taylor> other tables TVCT, etc use the ATSC CRC..  This kind of
    Taylor> makes things a pain.. Then again ATSC just makes me mad
    Taylor> about how the US has to be different.. No point in
    Taylor> starting that argument here..

Maybe we should add a flag to the section filters, since the user
would know if the program is filtering for ATSC specific sections or not.

    >> I don't know much about mythtv yet, so I will have to learn
    >> about it's structure a litte more.

    Taylor> Well ask away.. I'll be glad to help you along..

Well, right now I am still in the setup phase. I wanted to use my DVB
card and my PVR350, but although DVB only works for the setup, as soon
as I add the PVR I get a segfault when I try to enter the Inputs
menue. I will play around some more and see what works.

Concerning the CAM support, I wanted to warn you that not all DVB
cards will have CAM drivers that need support from the link layer and
up. Twinhan has cards that have all layers on board and only need to
be send commands. Others may have software Cams that only need to be
send PIDs and than communicate with a smartcard. So I decided to do
CAM support in libdvb via a kind of server program that gets the PIDs
via TCP port and does the rest itself. So that your application always
has the same interface regardless of what the CAM server needs to do.
Of course you don't need to do that via TCP, but you may need to
change the CiHandler class accordingly.


| Dr. Marcus O.C. Metzler        |                                   |
| mocm at metzlerbros.de            | http://www.metzlerbros.de/        |
 |>>>             Quis custodiet ipsos custodies                 <<<|

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