[mythtv] Assistance debugging a DVB/PMT tuning problem

Tom Dexter digitalaudiorock at gmail.com
Thu Jan 24 16:36:49 UTC 2008


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

Here's some very suspect output from "dvbsnoop -s pidscan".  If I tune
to another PBS local station (one that's further away from me, which I
don't get too reliably), which should have the same feed as the one I
can't tune, I get this:

---------------------------------------------------------
Transponder PID-Scan...
---------------------------------------------------------
PID found:    0 (0x0000)  [SECTION: Program Association Table (PAT)]
PID found:   48 (0x0030)  [SECTION: Program Map Table (PMT)]
PID found:   49 (0x0031)  [PES: ITU-T Rec. H.262 | ISO/IEC 13818-2 or
ISO/IEC 11172-2 video stream]
PID found:   52 (0x0034)  [PES: private_stream_1]
PID found:   58 (0x003a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found:   74 (0x004a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found:   80 (0x0050)  [SECTION: Program Map Table (PMT)]
PID found:   81 (0x0051)  [PES: ITU-T Rec. H.262 | ISO/IEC 13818-2 or
ISO/IEC 11172-2 video stream]
PID found:   84 (0x0054)  [PES: private_stream_1]
PID found:   90 (0x005a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found:   96 (0x0060)  [SECTION: Program Map Table (PMT)]
PID found:   97 (0x0061)  [PES: ITU-T Rec. H.262 | ISO/IEC 13818-2 or
ISO/IEC 11172-2 video stream]
PID found:  100 (0x0064)  [PES: private_stream_1]
PID found:  122 (0x007a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 1034 (0x040a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 1066 (0x042a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 1082 (0x043a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 7424 (0x1d00)  [SECTION: ATSC reserved]
PID found: 7681 (0x1e01)  [SECTION: ATSC reserved]
PID found: 8187 (0x1ffb)  [SECTION: ATSC reserved]
PID found: 8191 (0x1fff)

That one gets the PMT at 0x0030.  Here's the same scan using the
problem channel 58.1:

---------------------------------------------------------
Transponder PID-Scan...
---------------------------------------------------------
PID found:    0 (0x0000)  [SECTION: Program Association Table (PAT)]
PID found:   49 (0x0031)  [PES: ITU-T Rec. H.262 | ISO/IEC 13818-2 or
ISO/IEC 11172-2 video stream]
PID found:   52 (0x0034)  [PES: private_stream_1]
PID found:   58 (0x003a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found:   74 (0x004a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found:   81 (0x0051)  [PES: ITU-T Rec. H.262 | ISO/IEC 13818-2 or
ISO/IEC 11172-2 video stream]
PID found:   84 (0x0054)  [PES: private_stream_1]
PID found:   90 (0x005a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found:   97 (0x0061)  [PES: ITU-T Rec. H.262 | ISO/IEC 13818-2 or
ISO/IEC 11172-2 video stream]
PID found:  100 (0x0064)  [PES: private_stream_1]
PID found:  122 (0x007a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 1034 (0x040a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 1066 (0x042a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 1082 (0x043a)  [SECTION: ISO/IEC 13818-6 reserved]
PID found: 7424 (0x1d00)  [SECTION: ATSC reserved]
PID found: 7426 (0x1d02)  [SECTION: ATSC reserved]
PID found: 7681 (0x1e01)  [SECTION: ATSC reserved]
PID found: 7682 (0x1e02)  [SECTION: ATSC reserved]
PID found: 8187 (0x1ffb)  [SECTION: ATSC reserved]
PID found: 8191 (0x1fff)

That shows no PMT.  Note however that they both have audio and video
streams at 49 and 52, which is what my dvbscan found, and which works
in mplayer.  I can't imagine what dvbscan is doing to get that without
a PMT unless it's just using the first audio and video streams it runs
into.

The broadcaster certainly appears to be doing something strange though.

Tom


More information about the mythtv-dev mailing list