[mythtv-users] Autorescheduling after a recording failure

[f-myth-users at media.mit.edu]

I've been putting together some ideas for a rather paranoid bit of
automation that checks a number of attributes about a recording to
decide whether it failed and should be rescheduled (e.g., zero-length
file, too short for expected length (just added this one tonight; see
my previous message :), no audio or average level too low over more
than n seconds, too much black video, too many identical frames of
video, excessive snow, station EAS dropin detected, etc).  The idea is
to notice as fast as possible and queue the rescheduling immediately,
since often shows are repeated 2 or 3 hours later and then not again,
and that's not fast enough to guarantee that anyone will have checked
to see if it came out okay (since typically no one will check until
maybe the next day at best and maybe days later at worst).

The question is, given that the automation detects a failure, is there
an easy way of telling Myth "pretend that you didn't record this and
reschedule"?  I'm interested in both 18 and 19, since these machines
will eventually get migrated to 19.  Ideally, I'd like to be able to
issue a MySQL command that modifies some table(s) to believe the
episode simply never recorded (is modifying "oldrecorded" and
"recordprogram" enough?) and then force an immediate recomputation, or
something like that, and I'm looking for the easiest hook I can use.
(Assume I know at least the chanid,starttime tuple for the recording
that's failed and/or that the automation can look up other stuff in
the database if it has to.)

Thanks.

P.S.  I have some potential ideas for how to detect most of the
features mentioned above, although if anyone has any suggestions.
please feel free to send 'em my way.  Recognizing excessive snow
could be tricky, and the Emergency Alert Service dropins might also be
tricky unless I scan the entire audio track for the alert tones or
something... (They seem to happen every couple of weeks at random
late-night times here and can be pretty disruptive.)  The "identical
frames" and/or "black video" takes care of one of our PBS affiliates'
recurring late-night snafus that has a tendency to air the promos
between shows, but then nothing but black video (except for the
station logo) for the entire duration of the show; seems they have
some problem with their station automation but nobody's awake at that
time of night to notice, so they air 5 black "shows" in a row with
promo breaks in between.  Etc.  Is there something in the commflagger's
output I can use to detect black video and/or no change in video?  Too
few GOPs or something?