[mythtv-users] ATSC -scanning

Matthew Zimmerman mzimmerman at gmail.com
Wed Feb 18 21:08:14 UTC 2009

Maybe I'm missing something, but why aren't you just using
mythtv-setup to scan the channels?...

What card do you have?  Using QAM-256 and a pchdtv5500 this was a
piece of cake.  The only hard part about it was giving the channels
the proper xmltvid values.


On Wed, Feb 18, 2009 at 12:39 PM, A JM <vbtalent at gmail.com> wrote:
> Geoff,
> I was actually trying to scan Cable. When I scanned 8VSB which I'm assuming
> is OTA it was the only thing that showed any signs of life - I made the
> mistake to "assume" that it was interchangeable with cable, wrong on my
> behalf!!
> I was successful last night in scanning cable (QAM) and have a channels.conf
> but no way to import it into Myth strangely enough... so my dilemma is how
> to import the channels.conf. I thought I could get sneaky and import it
> through my other DVB satellite card input and then change the cardid in the
> DB to point to the HD300 but it just locked up mythtv-setup, so I guess I
> have to manually set up the DB instead???
> It looks like this:
> KNTV-HD :207000000:QAM_256:65:68:4
> NBC Wea :207000000:QAM_256:81:84:5
> KBWB-HD :503000000:QAM_256:49:52:3
> It's kind of strange that there isn't a place to actually import a
> channels.conf for this card or I just don't know where it is. According to
> the wiki it should be located with the channel scan features in
> mythtv-setup, but it isn't, there's no scan type option allowed for
> importing a channels.conf file...
> From the wiki:
> *******************************************************************************************************************************************************************************************
> dtv_multiplex
> You may have noticed that many of your channels are on the same frequency
> with different Program ID's (and thus different Video and Audio ID's as
> well). This is because each frequency has the ability to carry many
> different streams of data, each is given their own id, with a program id for
> each channel referencing these video and audio id's. MythTV only needs the
> frequency and Program ID to properly tune a channel. The dtv_multiplex table
> is how MythTV keeps track of the frequencies for channels.
> You can try using mythtv-setup's channel scan to try and find channels. Many
> find this won't work properly though. If things work well it should find
> all, or nearly all the channels you have in your custom channels.conf file.
> This will also have the added benefit of populating your dtv_multiplex
> table. If it doesn't work it may populate with non-existant channels and
> non-useful frequencies.
> The final option is to import your custom channels.conf file. This won't
> work 100% properly and you will still have to edit the channels table, but
> it should give you a proper dtv_multiplex table.
> It is suggested to modify or verify the table manually using [phpMyAdmin], a
> web based MySQL management tool. The table has 5 fields which we will find
> important,
> mplexid is the individual id number for the frequency entry. Ideally they
> will be in numerical sequence, ie 1,2,3,4,5. If you 'Delete all capture
> cards' when you start, the id's will be in frequency order.
> sourceid is the source for which the entry corresponds to, if your digital
> zap2it lineup is the second source you create in mythtv set, then this would
> be sourceid = 2. (Note that you can create your digital tuner in the Capture
> Card section first and its cardid will be '1', but it will be associated
> with sourceid =2.)
> frequency is the frequency. Each frequency needs only be in the table once
> per source. So if you have 3 channels on the same frequency, it only needs
> to be in dtv_multiplex once for that source.
> sistandard should be atsc, its default is dvb, so make sure its correct. Use
> 'update channel set sistandard = "atsc" where sourceid = 2;' to set this for
> all channels in sourceid 2.
> modulation should be qam_256, for North American cable systems.
> Now that dtv_multiplex is ready, print or write down what frequencies
> correspond to what mplexid, we will need these for the channel table.
> channels
> Now we can modify the channels table. Since we've already populated the
> table with the channel information for the guide, all we need to do is
> adjust the entries so that MythTV knows how to tune the channel. This only
> involves changing two fields, mplexid and serviceid.
> In mysql use:
> update channel set mplexid='x', serviceid='y' where channum='123';
> To see what you are doing, try:
> select chanid, channum, callsign, mplexid, serviceid from channel where
> sourceid='2';
> (presuming that your HD3000 is sourceid 2). This will list the details for
> the 29 or whatever number of usable channels you receive.
> You may be asking, "What about chanid, channum and freqid?". Well, none of
> these really matter when it comes to tuning the channel. chanid is the
> unique number MythTV gave that channel, it should be the sourceid followed
> by the channel number. freqid should be the same as channum which should be
> the channel your cable company assigned.
> Now what you will need to do is use the information in your custom
> channels.conf file to enter the appropriate mplexid for the frequency of the
> channel from dtv_multiplex into mplexid. The other field, serviceid, is the
> programid number, the last number in the channel information line of
> channels.conf.
> *******************************************************************************************************************************************************************************************
> Is this still good for doing this manually? It seems like there shold be a
> better way to get this into the DB than to have to do it manually...
> Thanks,
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