Comskip Support Forum

Hi Erik...

Is there a way to set the maximum non-uniformity for a black frame, similar to the way that you can set the maximum volume allowed in a black frame with the max_volume=X option. At first I thought that the non_uniformity=X option works that way but it does not after testing.

Since the conversion to digital broadcast here in the US, true black frames between commercials in a commercial break, and between show segments and commercial breaks, are always very black with Brightness=15-16 and with non-uniformity of 0-5.

On shows/movies like Stargate Universe, where the whole show is dark and shadowy, many false positive black frames are flagged based on low brightness with non-uniformity values of 150-300, versus non-uniformity of 0-5 for a true black cut frame at a commercial brake.

Some of these false black frames will come close to standard commercial lengths and will be flagged as commercials.

Having a max_non_uniformity option that works similar to the max_volume option for US OTA could nearly eliminate false positive black frames. Possibly having the non-uniformity=X option do double duty creating cutpoints and eliminating black frames with high non-uniformity values.

Thanks,
Chris

From comskip.txt inside the distribution zip file

;Frame is pure black if the average brightness is less then this
max_avg_brightness=25 (10-255)

Set to 17 or 18


;Frame not pure black if a small number of the pixels of the frame has a brightness greater than this. To decide if the frame is truly black, comskip will also check average brightness (scale 0 to 255)
;; If more then about 10% of the frame has a higher brightness then test_brightness the frame is not regarded black
test_brightness=40 (10 - 255)

Try 20 or 25