[mythtv] Assistance debugging a DVB/PMT tuning problem

Tom Dexter digitalaudiorock at gmail.com
Thu Jan 24 15:25:40 UTC 2008


On Jan 23, 2008 5:01 PM, Tom Dexter <digitalaudiorock at gmail.com> wrote:
> On Jan 23, 2008 4:42 PM, Janne Grunau <janne-mythtv at grunau.be> wrote:
> >
> > The cable provider doesn't seem to transmit a PMT
> > on the announced PID. I don't know where dvbscan gets the video and
> > audio from. running dvbsnoop on PID 0x0 and 0x30 might give further
> > hints.
> >
> >
> > Janne
>
> Thanks Janne!  This is broadcast by the way, not cable.
>
> I'm installing dvbsnoop now and will see what it shows.
>
> Tom
>
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.

Anyway, doing that I was able to run 'dvbsnoop -n2 0x0', but trying
0x30 just hung with no output.  Here's the output using 0x0:

dvbsnoop V1.4.00 -- http://dvbsnoop.sourceforge.net/

------------------------------------------------------------
SECT-Packet: 00000001   PID: 0 (0x0000), Length: 24 (0x0018)
Time received: Thu 2008-01-24  10:11:21.607
------------------------------------------------------------
  0000:  00 b0 15 07 d9 cd 00 00  00 03 e0 30 00 05 e0 50   ...........0...P
  0010:  00 06 e0 60 56 39 47 43                            ...`V9GC

PID:  0 (0x0000)  [= assigned for: ISO 13818-1 Program Association Table (PAT)]
Guess table from table id...
PAT-decoding....
Table_ID: 0 (0x00)  [= Program Association Table (PAT)]
section_syntax_indicator: 1 (0x01)
(fixed): 0 (0x00)
reserved_1: 3 (0x03)
Section_length: 21 (0x0015)
Transport_Stream_ID: 2009 (0x07d9)
reserved_2: 3 (0x03)
Version_number: 6 (0x06)
current_next_indicator: 1 (0x01)  [= valid now]
Section_number: 0 (0x00)
Last_Section_number: 0 (0x00)

    Program_number: 3 (0x0003)
    reserved: 7 (0x07)
    Program_map_PID: 48 (0x0030)

    Program_number: 5 (0x0005)
    reserved: 7 (0x07)
    Program_map_PID: 80 (0x0050)

    Program_number: 6 (0x0006)
    reserved: 7 (0x07)
    Program_map_PID: 96 (0x0060)

CRC: 1446594371 (0x56394743)
==========================================================


------------------------------------------------------------
SECT-Packet: 00000002   PID: 0 (0x0000), Length: 24 (0x0018)
Time received: Thu 2008-01-24  10:11:21.686
------------------------------------------------------------
  0000:  00 b0 15 07 d9 cd 00 00  00 03 e0 30 00 05 e0 50   ...........0...P
  0010:  00 06 e0 60 56 39 47 43                            ...`V9GC

PID:  0 (0x0000)  [= assigned for: ISO 13818-1 Program Association Table (PAT)]
Guess table from table id...
PAT-decoding....
Table_ID: 0 (0x00)  [= Program Association Table (PAT)]
section_syntax_indicator: 1 (0x01)
(fixed): 0 (0x00)
reserved_1: 3 (0x03)
Section_length: 21 (0x0015)
Transport_Stream_ID: 2009 (0x07d9)
reserved_2: 3 (0x03)
Version_number: 6 (0x06)
current_next_indicator: 1 (0x01)  [= valid now]
Section_number: 0 (0x00)
Last_Section_number: 0 (0x00)

    Program_number: 3 (0x0003)
    reserved: 7 (0x07)
    Program_map_PID: 48 (0x0030)

    Program_number: 5 (0x0005)
    reserved: 7 (0x07)
    Program_map_PID: 80 (0x0050)

    Program_number: 6 (0x0006)
    reserved: 7 (0x07)
    Program_map_PID: 96 (0x0060)

CRC: 1446594371 (0x56394743)
==========================================================

Hopefully that worked correctly, given the kludged way I had to go
about it.  I'd love to get tzap working correctly with the right
channels.conf format and retry scanning 0x30.  That format doesn't
appear to be documented anywhere I can find.

Tom


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