[mythtv] Re: DVB/ATSC channels.conf import troubles

[Todd Ignasiak]

Yeah, your dtv_muhltiplex entries look fine, I guess Christian's patch
must have taken care of that (I haven't seen that code, sorry).   So,
my theory is incorrect (assuming that the "channel" entries correctly
refer to the mplexid's for each channel).

-Todd

On 7/16/05, Johnny Graettinger <johnny531 at gmail.com> wrote:
> Thank you both for your quick responses.
> 
> Christiaan - Right, I should have been more clear. The actual
> channels.conf I'm importing is a modified version of the one
> constructed through playing with azap (which does include audio/video
> pid's). The imported version is:
> 
> CBS-DT:625781200:QAM_256:1
> PBS-DT:625781200:QAM_256:2
> MPT-DT:625781200:QAM_256:3
> FOX-DT:745787200:QAM_256:1
> ABC-DT:631781500:QAM_256:1
> NBC-DT:631781500:QAM_256:2
> WEATHER-DT:673783600:QAM_256:1
> 
> Where for each station I have verified that the trailing number is the
> correct program number (which, I assume, enumerates video/audio pid
> pairs counting from 0).
> 
> 
> Todd:
> 
> Yep, poking around in the database reveals my dtv_multiplex is quite
> similar. I don't pretend to understand all of it, in particular the
> meanings of these defaults, but I've included it for inspection:
>  (1,1,NULL,NULL,625781200,'a',0,'auto','v','qam_256','a','auto','a','auto',0,'auto','a','auto','atsc',33,20050716132646);
> (2,1,NULL,NULL,745787200,'a',0,'auto','v','qam_256','a','auto','a','auto',0,'auto','a','auto','atsc',33,20050716132646);
> (3,1,NULL,NULL,631781500,'a',0,'auto','v','qam_256','a','auto','a','auto',0,'auto','a','auto','atsc',33,20050716132646);
> (4,1,NULL,NULL,673783600,'a',0,'auto','v','qam_256','a','auto','a','auto',0,'auto','a','auto','atsc',33,20050716132646);
> 
> 
> Johnny
> 
> 
> 
> 
> 
> On 7/16/05, Christiaan Lutzer <mythtv.lutzer at gmail.com> wrote:
> > Johnny, what are the last two numbers in your channels.conf file,
> > "209" and "212"?  If you applied the patch that I've submitted, the
> > format is:
> >
> > channel name : frequency (Hz) : QAM modulation mode : MPEG-2 TS Program
> > Number
> >
> > I have Comcast as well (Comcast Digital Cambridge, MA) and I've never
> > seen an MPEG Program Number exceed 20 or so.  It's almost like you are
> > specifying the video/audio PID instead.
> >
> > The parsing code would ignore the "212" in the ATSC case, and use 209
> > as the program number.  I would suspect that mythbackend would not be
> > able to find any program with that PN, and give you black video.
> >
> > Just some thoughts.
> >
> > C.
> >
> > 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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> > >
> >
>