[mythtv-users] Damaged MPEG looks fine?

[Enigma]

I am having a problem with the programs recorded from QAM-256 (SD 
digital) on my Kworld ATSC-115.  The recordings look fine with no 
obvious artifacts but the commercial flagger seems to choke on them.  
The recording process seems smooth, with no iobound errors.  The flagger 
reports thousands of errors along the lines of:

2007-11-07 23:41:13.123 AFD Error: Unknown decoding error
[mpeg2video @ 0xa72f92e8]get_buffer() failed (stride changed)

along with many of the "normal" ac-tex errors one sees in a damaged MPEG:

[mpeg2video @ 0xa72e4168]invalid mb type in P Frame at 3 15
[mpeg2video @ 0xa72e4168]ac-tex damaged at 35 16
[mpeg2video @ 0xa72e4168]ac-tex damaged at 0 18
[mpeg2video @ 0xa72e4168]ac-tex damaged at 31 19

Is anybody familiar with the "stride changed" error above?  Is there any 
way to track down where this is happening?  The signal seems strong and 
the picture is good, is it possible that my cable company is using 
non-standard mpeg2 in their streams?  Or is more likely this is 
happening in the tuner or card?