Difference between revisions of "Adding Digital Cable Channels (For ATSC/QAM Tuner Cards -- USA/Canada)"

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Jason Beck wrote this to the mythtv-users list. It's since been the defacto for getting QAM working for HDTV tuner cards. My hope is to update this for the soon to come 0.19 release and perhaps add more information to the process to make it even "easier".

MythTV Database

There are two tables in the MythTV that we are concerned with, the channels table and the dtv_multiplex table. dtv_multiplex stores the frequencies for the channels, channels stores the actual channel information, with a reference to the dtv_multiplex table.

The best method for adding HDTV channels to the db is to populate channels with the channel information from your guide source (Zap2It, etc), then modify the table to add the frequency, etc. information.

azap

First a list of the receivable channels must be created. I have found MythTV's scanner to not do an adequate job of finding the appropriate channels. In order to ensure that all channels you are able to receive are found it is suggested to use the dvb-apps scan utility.

Run atscscan with the default table as an arguement, for over-the-air ATSC,

atscscan atsc/us-ATSC-center-frequencies-8VSB

For open signals on a cable line, one of these two should work. HRC and IRC are different frequency methods that can be used, its hard to tell which your cable company uses without trying both,

atscscan atsc/us-Cable-HRC-center-frequencies-QAM256

or

atscscan atsc/us-Cable-IRC-center-frequencies-QAM256

Collecting Channel Data

Jason's Original Email

http://www.gossamer-threads.com/lists/mythtv/users/150118?do=post_view_threaded#150118

If your provider is not kind enough to send the PSIP
info you will have to add the channels manually to the
database.

I'll try to explain how using you channels.conf as an
example. The database tables that need to be modified
are channel and dtv_multiplex. dtv_multiplex should
be populated by the channel scan and the channel table
you will need to modify yourself. Below is an example
of how you would setup your NBC (assuming
ch#707)channel in Myth.

1.) go to zap2it and build your listing for your local
HD broadcast channels.

2.) assign that listing to your dvb 3k in mythtvsetup

3.) go into the channel editor (still in mythtvsetup)
select your new listing and do a scan (select type
"cable")
The scan will take some time. Mostly likely you won't
really get anything useful, but what this will do it
populate the dtv_multiplex table in your db. You will
need this later on.

4.) exit mythtvsetup and run mythfilldatabase. This
will now provide you with your xmltvids to callsign
mappings.
At this point you still will not be able to tune
anything yet so don't try.

5.) ***Important*** stop mythbackend.

6.) edit your channels.conf and remove your PSIP
values. You don't need them for Myth. So your file
will look like this.
NBC:561000000:QAM_256:0:0
ABC:561000000:QAM_256:0:0
CBS:567000000:QAM_256:0:0
FOX:567000000:QAM_256:0:0

7.) go ahead and fire up azap and tune a channel.
$ azap -r NBC

8.) in a second terminial run dvbscan -c
$ dvbscan -c
What you need is the serviceid. This is the number in
the [000#] at the far left. Your provider will most
likely be using the same frequency for multiple
channels. So you may have more then one service per
freq. In this example your serviceid for NBC would be
2.
Example:
dumping lists (1 services)
[0002] (0x0002) 00: PCR == V V
0x0010 A 0x0011 (eng)
Now stop your dvbscan and azap tune.

9.) log into your database.
$mysql -u root -p mythconverg
To tune the 3k you will need to find the mplexid for
you known frequency.

10.) finding the mplexid
mysql> select mplexid from dtv_multiplex where
frequency = '561000000';
+---------+
| mplexid |
+---------+
| 25 |
+---------+
1 row in set (0.01 sec)
Write down the mplexid value. For example sake we
will say it was 25.

11.) Now you are ready to setup the channel. You have
the freqency (561000000),mplexid(25),and the
serviceid(2). Assuming that you now have a channel
707 from the previous mythfilldatabase above.
mysql> update channel set freqid="561000000" where
channum=707;
mysql> update channel set mplexid="25" where
channum=707;
mysql> update channel set serviceid="2" where
channum=707;
You may want to do a quick check to make sure all
looks good.
mysql> select * from channel where channum=707;
mysql> quit

12.) Start mythbackend

13.) Start up the frontend and test.

-- A couple of things I ran across later with the 3k.

By default the 3k will be set to record in PS mode. I
had wierd fastforward and rewind problems. In
mythtvsetup under capture cards-->dvb-->Advanced
settings I selected the "Use TS instead of PS" option
and the ffw and rew problems went away.

Also stopping the backend is only really needed to do
the azap tune. So while your there you may just want
to run the scan for serviceids for your 4 channels so
you only have to do it once.

I hope this helps. I just went through this about a
week ago and it was not easy to find all of the info.
Alot for trial and error. Let me know how it works
out for you...
-jason