[mythtv-users] Strange problem with local PBS SD station (OTA)

[Tom Dexter]

I'm in central NJ.  There's a DTV PBS station literally a few towns
from me (WNJB-DT 58-1) that I've always been able to get in myth on my
HD-5500 cards.

I fairly certain they used to broadcast in one of those odd widescreen
formats that's not actaully HD, but a low bitrate 1820x1080 broadcast
with black bars built into the broadcast and 4x3 content.  It appears
they recently switched to actual SD.  For some reason, myth can't get
a lock on it at all, in spite of the fact that a query of the tuner
shows a lock and really good signal strength.  It's some issue with SD
in general however, as I get a New York SD PBS channel (WNJN-DT 50-1)
with no problem even with around 50% signal.

Here's the signal I get with the station I can't lock on:

status SCVYL | signal  84% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status SCVYL | signal  86% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status SCVYL | signal  84% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status SCVYL | signal  86% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status SCVYL | signal  85% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status SCVYL | signal  85% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status SCVYL | signal  87% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK
status SCVYL | signal  85% | snr  11% | ber 00000000 | unc 00000000 |
FE_HAS_LOCK

...certainly nothing wrong there.  I get the "you should have received
a lock by now" prompt on the frontend, and if I hit enter and wait it
never gets a lock.  All I get on the backend is a zero length mpeg
file.  The frontend logs show no error except a pre-buffering pause.
Here's what I get on the backend:

2008-01-21 13:01:05.554 AFD: Opened codec 0x81c91d0, id(MPEG2VIDEO) type(Video)
2008-01-21 13:01:05.560 AFD: Opened codec 0x822b210, id(AC3) type(Audio)
[mpeg2video @ 0xb733a4a8]00 motion_type at 14 6
[mpeg2video @ 0xb733a4a8]00 motion_type at 18 8
[mpeg2video @ 0xb733a4a8]00 motion_type at 5 8
[mpeg2video @ 0xb733a4a8]slice mismatch
[mpeg2video @ 0xb733a4a8]ac-tex damaged at 19 10
[mpeg2video @ 0xb733a4a8]00 motion_type at 24 11
[mpeg2video @ 0xb733a4a8]00 motion_type at 1 12
[mpeg2video @ 0xb733a4a8]00 motion_type at 11 13
[mpeg2video @ 0xb733a4a8]ac-tex damaged at 5 14
[mpeg2video @ 0xb733a4a8]ac-tex damaged at 23 15
[mpeg2video @ 0xb733a4a8]ac-tex damaged at 2 16
[mpeg2video @ 0xb733a4a8]00 motion_type at 16 17
[mpeg2video @ 0xb733a4a8]00 motion_type at 4 18
[mpeg2video @ 0xb733a4a8]ac-tex damaged at 0 19
[mpeg2video @ 0xb733a4a8]ac-tex damaged at 2 20
[mpeg2video @ 0xb733a4a8]00 motion_type at 36 21
[mpeg2video @ 0xb733a4a8]ac-tex damaged at 33 22
[mpeg2video @ 0xb733a4a8]mb incr damaged
[mpeg2video @ 0xb733a4a8]00 motion_type at 1 24
[mpeg2video @ 0xb733a4a8]mb incr damaged
[mpeg2video @ 0xb733a4a8]00 motion_type at 2 26
[mpeg2video @ 0xb733a4a8]00 motion_type at 7 27
[mpeg2video @ 0xb733a4a8]00 motion_type at 12 28
[mpeg2video @ 0xb733a4a8]00 motion_type at 4 29

I have a Samsung HD receiver which can pick it up just fine.  When
myth is trying to tune I get (LA_VG) as apposed to the (LAMVG) I
usually get.  Looking here:

http://mythtv.org/docs/mythtv-HOWTO-23.html#ss23.22

...it appears that means it's not dealing with the mpeg stream.  Is
this possibly something strange they're doing on their end?

One thing confuses me about those backend errors...with DTV the
frontend does all the decoding.  Are those errors just from the
backend attempting to verify that it's an mpeg stream?

Thanks in advance for any suggestions.

Tom