[mythtv] alternative method for commercial skipping

[Marc Kessels]

In the place where I live (The Netherlands) we do not have the  blank 
screens before and after the commercials, but there is another way to find 
out if there are commercials on the screen: All channels are so kind to 
display a logo/icon in a corner of the screen when a program is showing, 
but not when the commercials are on... I think this would be a nice 
addition to the current method of commercial skipping (supposing that more 
channels abroad have the same habit)

what I would propose (but please give your comments):

1. first it needs to find the logo itself. (one time only per channel):
1.1 the channel is captured for some time (when no commercial is 
transmitted), and all pixels which are not constant, are put to black
1.2 anything remaining should be the logo, thus, store this picture and the 
position where it appeared on the screen. ( the picture can be used for the 
EPG as well)

2. during capturing (liveTV or recording), the stored image is compared 
with the area where the logo is expected. if it deviates too much: a 
commercial is (due to be) transmitted. This frame number can than be stored 
somewhere. (tiny issue to solve: the logo disappears about 2 seconds before 
the commercials begin, and pops up again 2 seconds after the program 
continues.)

This latter part is very similar with the current method, since  there the 
program compares the captured frame with a black "image", so this should 
not be too hard to make.
So I am afraid that the hard part is located in part 1 (at least too hard 
for me).... But another option would be to do this part manually and put 
the images and position on a website so that other users can grab the info 
from there. (just like the EPG)

If I get some help from someone (preferably someone familiar with 
commercial_skip.cpp) I think I can program part 2 and put up a website with 
the info from manual part 1.

already some issues I am thinking on are:
where to put the logo position (I think it should be in the database)
how to add this option in the program itself (for me a replacement of 
commercial_skip.cpp would do, but I think this is not the way it should be...)

Marc