[mythtv-users] Automatic Commercial Detection - how to get it

Stephen Tait tait at digitallaw.co.uk
Wed Sep 22 14:22:08 EDT 2004

At 05:52 22/09/2004, you wrote:
> > > What I have noticed however that every channel here in the UK pumps 
> up the
> > > volume considerably when switching to ads, which always has me reaching
> > > for
> > > the mute button. Is there any way commflag can be confugled to take this
> > > into account also? Does the same kinda thing happen in the US?
> >
> > Absolutely does happen in U.S. Commercials are like people, they speak
> > loudly to sound more intelligent.
>I've yet to look at the audio data enough to know this or not, but I've heard
>and read that it's not volume, it's something else that changes that makes
>it seem louder.  I don't know.  I haven't even delved into trying to process
>the audio to detect commercials, that's a whole 'nother beast.  Things like
>audio silence during blank-frames and such would really help proper

I'm not a coder by any stretch of the imagination, but if you like I'll see 
if I can pull apart a few MPEG's and have a look at the waveforms and 
suchlike and see if I can figure out what's going on.

As I don't know how Myth works (i.e. how it would "see" the audio if and 
when it scanned it - I'm imagining just as a regular waveform), if anyone 
could proffer an idea for the best way for a patch that looked at the audio 
would work, I'd be much obliged. Also, if there's any audio manipulation 
done by either Myth's software encoding or by the ivtv-range that anyone 
knows about I imagine it would prove very helpful. In the meantime I'll 
check out some of the other links posted above.

Bear in mind I've only got access to the UK's terrestrial channels, so if 
there's any major differences between these and your NTSC streams I imagine 
I'll be up shit creek ;) 

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