[mythtv] DVB/ATSC channels.conf import troubles

[Todd Ignasiak]

Have you verified the channel data in MythTV, to make sure it was
imported as you expected?

The channel config data is stored in the MySQL database.  So, you need
some tool to view/edit it, such as mysqldump, webmin-mysql,
MythWeb(modified to see the values you need), etc.

In the "channel" table, the channel listing with the name/number shown
in the guide, associateed XMLTV ID, and various other information is
present - including three items used for ATSC/QAM:  mplexid,
serviceid, atscsrcid.    If your channel scan is not working, these
values are probably not getting populated.

serviceid and atscsrcid refer to the program numbers from the
transport stream.  serviceid is basically the subchannel number, so
try values like 1 or 2 when testing it initially.

mplexid is a pointer referring to an entry in the "dtv_multiplex"
table.  This is where the frequency used by each channel is stored,
which is obviously important in your situation.  Here is a sample of
the contents from my mysqldump:

CREATE TABLE `dtv_multiplex` (
  `mplexid` smallint(6) NOT NULL auto_increment,
  `sourceid` smallint(6) default NULL,
  `transportid` int(11) default NULL,
  `networkid` int(11) default NULL,
  `frequency` int(11) default NULL,
  `inversion` char(1) default 'a',
  `symbolrate` int(11) default NULL,
  `fec` varchar(10) default 'auto',
  `polarity` char(1) default NULL,
  `modulation` varchar(10) default 'auto',
  `bandwidth` char(1) default 'a',
  `lp_code_rate` varchar(10) default 'auto',
  `transmission_mode` char(1) default 'a',
  `guard_interval` varchar(10) default 'auto',
  `visible` smallint(1) NOT NULL default '0',
  `constellation` varchar(10) default 'auto',
  `hierarchy` varchar(10) default 'auto',
  `hp_code_rate` varchar(10) default 'auto',
  `sistandard` varchar(10) default 'dvb',
  `serviceversion` smallint(6) default '33',
  `updatetimestamp` timestamp(14) NOT NULL,
  PRIMARY KEY  (`mplexid`)
) TYPE=MyISAM;

--
-- Dumping data for table `dtv_multiplex`
--

INSERT INTO `dtv_multiplex` VALUES
(1,1,4111,0,555000000,'a',NULL,'auto',NULL,'qam_256','a','auto','a','auto',0,'auto','auto','auto','atsc',31,20050714205200);
INSERT INTO `dtv_multiplex` VALUES
(2,1,NULL,NULL,603000000,'a',NULL,'auto',NULL,'qam_256','a','auto','a','auto',0,'auto','auto','auto','atsc',33,20050712175259);
INSERT INTO `dtv_multiplex` VALUES
(3,1,NULL,NULL,609000000,'a',NULL,'auto',NULL,'qam_256','a','auto','a','auto',0,'auto','auto','auto','atsc',33,20050712175305);
INSERT INTO `dtv_multiplex` VALUES
(4,1,NULL,NULL,615000000,'a',NULL,'auto',NULL,'qam_256','a','auto','a','auto',0,'auto','auto','auto','atsc',33,20050712175311);


HTH,

Todd


On 7/16/05, Johnny Graettinger <johnny531 at gmail.com> wrote:
> I'm running a recent svn copy patched with the changes Christiaan
> discusses for importing channels.conf in cases of DVB/ATSC cards. To
> that end, I've constructed a channels.conf via azap  & dvbtraffic
> containing pid's for each in-the-clear channel, eg:
> 
> CBS:625781200:QAM_256:209:212
> 
> On a perhaps related tangent, you'll notice that the frequencies used
> are non-standard. Comcast in baltimore uses HRC (harmonic resonance
> something?) rather than standard cable transmissions, so QAM scanning
> in mythtv has not worked for me, prompting a more manual approach.
> Indeed, I only got this working by using the recently added
> /util/scan/atsc/us-Cable-HRC-center-frequencies-QAM256 file within the
> dvb-apps distribution as a baseline.
> 
> azap -r CBS; dvbtraffic; cat /dev/dvb/adapter0/dvr0 > foo.mpg
> 
> works great, and resulting streams when viewed seem without error.
> 
> Sorry for all the background, now on to myth specifically:
> 
> Following Christiaan's lead, I rearranged channels.conf to follow the
> modulation with just a program number in the transport stream, and
> imported it into mythtv-setup. The import succeeds, but an effect I've
> noticed is that, in a video source containing only the imported
> transports, a full scan of existing transports immediately returns
> with error, and an existing transport scan simply sits indefinetly
> with the progress bar at 3%
> 
> However, not to be deterred, I gave mythbackend a try. Lo and behold,
> it gets a lock on the default channel for my HD-3000 tuner. But
> watching tv simply sits in a black screen for a while.
> 
> As a test, while it was sitting in such state I cat'd dvr0 to an mpg.
> The resultant mpg did increase in size, indicating the tuner was tuned
> to particular video and audio pid's, however was not playable (mpeg
> header not found).
> 
> One last strange issue. Another experiment I've performed is to start
> mythbackend so that it gets an initial signal lock on the default
> channel for the tuner. I then run dvbtraffic to confirm the tune.
> What I've found is that, per update, dvb traffic does occasionally
> print the pid's and bitrates I'd expect for the stream, but most of
> the time it prints out a large number of 1-4 kbit pid's, which I
> understand to be indicitave of a dirty or poorly locked signal.
> Further, if I leave the same instance of dvbtraffic running, and then
> kill the mythbackend instance, dvbtraffic immediately sorts itself out
> and prints the correct pid's/bitrates (no re-locking via azap
> necessary).
> 
> Is it because the lock in mythtv is poor that it's having trouble
> picking correct pid's for the stream? Or are these two completely
> seperate issues? And of course, any idea what could be causing the
> strange locking/dvbtraffic behavior? Or alternatively, how I might
> mangle the code in order to fix QAM scanning so myth finds these
> channels for itself?
> 
> Any help *much* appreciated
> 
> Johnny
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