[mythtv] New Method for Commercial Detection.

Lucas Meijer lucas at mach8.nl
Tue May 2 11:48:04 UTC 2006

Robert Dunn wrote:

> I was planning on doing solely mono-audio fingerprinting, and as 
> discussed in the PDF I linked to before, a low sample rate (5-8KHz) can 
> be used, so I imagine I can get it to be relatively low processor time 
> as the accuracy discussed in the article is not required here (this was 
> part of my experiments on the DSP). Additional video detection would be 
> later added, if the audio was not successful enough. The biggest Issue I 
> see is searching a large database of keys for the detection in real time.
Well, it's defenitely an interesting approach. My initial feelings are 
that the biggest problem will not
be in the technical side of identifying the audio, but in the 
'management' side, of how to keep an uptodate
list of commercial-audio-fingerprints...

The technique you mention of detecting a segment that is not recognized 
as a commercial between two
known commercials, and adding keys for that to the database is a pretty 
good idea. To keep that working
stably though, there need to be enough recordings over time..  if I 
don't record anything for two weeks,
chances are good all the known commercials have stopped airing, making 
the system unable to "relearn" the
new commercials..

One quickly goes to think of an online database of known commercials 
(probably region specific), but that
off course would have problems of its own: (deliberate) corruption of 
the database with incorrect fingerprints,
being the first one that comes to mind.

Nonetheless, I don't think any of these problems are impossible to 
solve, so I'd love to see some work in this area,
so far all commercial detection tricks that are implemented are video 
only.   Which reminds me, you'll probably need
to modify the base commdetector class to also supply an audio feed. I 
started doing this months ago, but never
got around finishing it. mostly because I didn't have any interesting 
brilliant idea on what to do with the audio feed once
I got it :)

Bye, Lucas

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