[mythtv] Commercial Flagging Idea

David Miller david3d at gmail.com
Tue Jul 5 12:38:10 EDT 2005

  Interesting stuff.  I figured I wouldn't be the first to come up
with this idea.  This would still seem to be a good method to aid in
detecting commercials especially with the blank audio between
commercials and average audio levels.  Now I wouldn't use this method
alone to detect commercials but anything that increases accuracy is a
good thing.  Also processing audio is very quick compared to video so
this would not add alot of time to the commercial flagging process.
  Has anyone ever thought of doing the commercial flagging portion of
the code to be more of a plugin architecture.  Where each flagging
method is a plugin.  I imagine there would be 2 classes of flagging
plugins, image based and audio based.  Where each plugin would add add
or subtract from a frame's or block of frames' probability of it being
a commercial.  Similar to how spam filtering on email works.  This
would allow for adding new methods very easily compared to the way
it's all written now as one class.  It would also allow each plugin to
have it's own settings page in the frontend and perhaps web interface
to tweak each filter for fine tuning.  This could also open up the
opportunity to have commercial flagging settings for each show you
record if the default settings weren't working well for a particular

On 7/5/05, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> David Whyte wrote:
> >On 7/5/05, David Miller <david3d at gmail.com> wrote:
> >
> >
> >> I had an idea on a new commercial flagging technique which would
> >>look at the average volume level of the audio between blank frames and
> >>scene changes to help aid in commercial detection.  Since commercials
> >>are typically much louder than a show.
> >>
> >I think this has already been suggested as an idea in the past.  It is
> >a good idea though as it is a common characteristic of commercials.
> >
> >
> And, when it was discussed, IIRC, it was determined that commercials are
> not generally louder than the rest of the show, but only seem that way
> due to normalization, compression, etc.  However, before and after a
> commercial break, the audio volume seemed to "always" fall to
> 0--something that "never" happens, even in a silent scene of a show.
> http://www.gossamer-threads.com/lists/mythtv/users/123827
> http://www.gossamer-threads.com/lists/mythtv/users/85156#85156
> and, see the links in
> http://www.gossamer-threads.com/lists/mythtv/users/85521#85521
> Mike
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