[mythtv-users] Real time commflagging of 1080i material from hdpvr

[Kevin Ross]

> The flagger does have some code in it to try to optimize things so
> that 1920x1080 doesn't take 27 times longer than 320x240 video
> (ie, 2073600 pixels vs 76800).  For instance, the blank frame detection
> short-circuits when it finds non-blank data.  The scene change code
> doesn't look at every pixel, it uses a variable sized grid of points
> in the frame.  It looks like I only change the grid spacing from every
> 8 pixels to every 10 pixels when going from 1280x720 to 1920x1080.
> If you want to try a test, you could edit 2 lines in the code and see
> what kind of speedup you can get on 1080 material.
> 
> Edit mythtv/programs/ClassicCommDetector.cpp and search for the
> following:
> 
>     if ((width * height) > 1000000)
>     {
>         horizSpacing = 10;
>         vertSpacing = 10;
>     }
>     else if ((width * height) > 800000)
>     {
>         horizSpacing = 8;
>         vertSpacing = 8;
>     }
> 
> Try changing the two 10's up there to 12 or 16.  That should speed up
> detection a little.  That whole section of logic could probably be
> cleaned up a bit to be hand-tuned to standard video sizes.  Patches
> are welcome if they give good results. :)

I build from source, so trying this won't be a problem at all.  I'll give it
a try tonight and report back.