[mythtv] Assistance debugging a DVB/PMT tuning problem

[Tom Dexter]

On Jan 24, 2008 11:09 AM, Mark Paulus <mark.paulus at verizonbusiness.com> wrote:
>
>
>
> Tom Dexter wrote:
> > Wow...is this turning into an exercise in futility...
> >
> > I've never had a need before to use any of these various utilities
> > before.  I'm assuming that in order to use dvbsnoop I need something
> > to tune in the station.  I have
> > media-tv/linuxtv-dvb-apps-1.1.1.20070114 installed under Gentoo which
> > has both the dvbscan I used before and tzap, which I want to use to
> > tune the channel.  From everything I can gather, tzap apparently wants
> > a channels.conf format that looks something like this (from the mythtv
> > wiki):
> >
> > SBS DIGITAL 1:564500000:INVERSION_AUTO:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_64:...
> > SBS DIGITAL 2:564500000:INVERSION_AUTO:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_64:...
> >
> > ...but no matter how I run dvbscan (even with -o zap, which is
> > supposed to be the default) I get a format like I posted earlier:
> >
> > WNJB-DT:183028615:8VSB:49:52:3
> > NJN-3:183028615:8VSB:81:84:5
> > NJN-4:183028615:8VSB:97:100:6
> >
> > ...which causes tzap to error out with "ERROR: error while parsing
> > inversion (syntax error)". I installed dvbtune, and that errors out
> > with "Unknown FE type. Aborting".  From what I'm reading that's caused
> > by changes in the DVB api.  The only option I could actually get
> > working was to let mythbackend do the tuning...but since mythtv can't
> > actually receive that channel, my only option was to plug the channel
> > number 58.1 into the cardinput table and start the frontend...jeeeez.
>
> Doing a google for 'tzap channels.conf' led me to this page, which
> might be helpful for settting up your channels.conf file:
> http://brej.org/dvb/
>
> I use the following script to help me investigate Transport Streams
> captured via my QAM-256 card from my cable provider.  It finds
> all the info about your stream, PAT, PMT and PID info:
>
> for i in "$@"
> do
>     dvbsnoop -n 10 -nph -s ts -tssubdecode -if "$i" > "$i.dvbsnoop"
> done
>
> To create a file, I use 'dvbstream <-c card> -o 8192 > file.ts'
> dvbstream can be found out there on the web somewhere.  Hmmm.  Looks
> like I am using a debianized version, so should be no problems finding
> a version.
>
Here's what I discovered.  If you use any of the dvb-t scan files that
come with dvbscan you get a channels.conf file in the format that tzap
expects.  However all those files are for non-US dvb-t.  I scanned
using the scan file
/usr/share/dvb/scan/atsc/us-ATSC-center-frequencies-8VSB which, unless
I'm missing something, is the only one for US OTA.  That creates the
shorter channel.conf file format.

Apparently that format can be tuned with azap.  I thought from
everything I read that azap was only for cable...apparently not.

Tom