[mythtv-users] How well does commercial detection work?

[Chris Pinkham]

> >I wonder if it would help to apply a narrow filter to get rid of high
> >frequency noise before testing whether a frame is blank?  This might
> >help for noisy signals without hurting things much for clean
> >signals...
> >  
> >
> I'd be interested in this.  In going through my programs last night, I 
> found that all my non-CBS recordings were about as close to 100% as I 

The commercial flagger calls NuppelVideoPlayer::InitVideo which calls
NuppelVideoPlayer::InitFilters, so if you have any playback filters
enabled, I believe they are also used for commercial flagging.  You can
test by setting up a playback filter to see if it makes any difference,
if so, we could possibly make a different setting for flagging filters
so we could apply filters for flagging but not for playback (if the user
so desired).

> can imagine.  The only one with issue was CBS and with strict detection 
> turned on I believe it missed on break and had one short 12 second false 
> positive and another 0 second false positive (makes me think we should 
> have some kind of minimum bound on commercial length inclusive with 
> strict detection to eliminate such short and obvious non-commercials). 

There already is a minimum length, if you are saw a 12-second or 0-second
false positive, there is a bug somewhere.  If you see something like
this again, can you re-run mythcommflag manually on that show with the
following command line (add in your own chanid/starttime of course) and
gzip and email me the output:


DEBUGCOMMFLAG=1 mythcommflag -v commflag --chanid CHANID --starttime STARTTIME > mythcommflag.out 2>&1

That will turn on a bunch of debug statements that I have in the code
and will print out information about every frame, as well as the blocks
that were defined/found and how the scores were adjusted for the blocks
based on the stats for the frames in each block.   This log may be huge,
so you probably need to gzip or even better bzip2 the file before emailing.

> Anyways, if you have an example of how to apply this filter to that 
> channel, I'd appreciate it and would love to test it's results.

Try setting a playback filter and see if that makes any difference.

-- 

Chris