[mythtv] New idea for commercial flagging...

Ed Wildgoose lists at wildgooses.com
Wed Dec 22 23:13:03 UTC 2004

Do you guys in the States have these lead in and lead out clips on all 
your shows?  In the UK all the advert breaks have a short burst of 
either a static frame saying some jazzed up version of the program name, 
or sometimes an animated version.

By "hashing" all frames in some sensible way (and ignoring blank frames) 
it should be possible to find a series of repeated frames that are near 
identical for a second or so.  These blocks of identical frames would 
then be our commercial lead in and our markers (perhaps optionally 
looking for a scene or blank frame afterwards to find the exact end of 
the commercial break.

Any thoughts on a sensible hashing function?  Might be almost a perfect 
identical frame for DVB users, but for analogue users there is going to 
be sufficient "noise" to make the detection of identical frames tricky.  
My first thought would be to break the frame up into, say, 8x8 pixel 
blocks, average the colour and then quantise this colour to a smaller 
range (say 1-8 instead of 1-256 for each colour).  Does this sound 
"fuzzy" enough to spot identical frames?  Anyone read any research 
papers on doing this that might have some better ideas..?  Anyone got a 
couple of hours free to try coding this up...?

Ed W

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