[mythtv] Alternative commercial flagging method

[Javier Santos]

There is a thread in slashdot about commercial detection and skipping:
http://slashdot.org/article.pl?sid=03/12/30/1327206

This is a fragment from one of the comments on that thread:


Actually, according to everything I've read, there is no actual increase of 
sound decibels in commericals. Here is an example I cut and pasted from 
somewhere..
"Technically, the maximum volume is the same for commercials and normal 
programming. If you watch the audio levels on a VU meter you will see that 
they peak at around the same level.

The difference is that advertisers make use of various tricks to make the 
commercials seem louder. Whereas a TV program will have a range of audio 
levels, commercials do tend to be full-on noisy. Tricks such as compression 
are also used to maintain constantly "louder" levels and try to attract 
attention.

So it's mainly a perceptual thing. Although the commercials don't reach a high 
volume, the way they are made gives the impression that they are louder."


Hope it helps,

Javier Santos




On Saturday 24 January 2004 14:07, Andrew Mahone wrote:
> On Saturday 24 January 2004 07:35, Liam wrote:
> > I've been playing with the commercial flagging routines and have come up
> > with a method that works well with the half-dozen british programmes I've
> > tried it on. It works in much the same way that the Scene Change +
> > Blankframes with different logic for deciding where boundries are. I
> > don't see any reason why it shouldn't work with US shows.
> >
> > Liam
>
> I'm building this now, and I'll try it out over the next week.  I'm glad to
> see somebody working on this, it's been on my gripes list for a while, but
> I spend too much time on filters to have even looked at the problem.  The
> existing detection fails badly on a number of my regular shows, frequently
> missing a start or end of a commercial and marking a large portion of a
> show as a commercial.  I generally just forward through commercials
> manually because of this.
>
> Have you considered taking audio into account as well?  I have no idea how
> hard it would be to analyze audio as well as video in the current framework
> for commercial detection, but it might be useful.  In the US, at least,
> it's common for commercials to be broadcast with significantly louder audio
> than regular programming.  Testing for this, and maybe testing spans
> between black frames / scene changes for reasonable "commercial" durations,
> could possibly make detection more accurate.