Global Motion Compensation and credits encoding

[numaios]

I've always read that GMC doesn't really improve subjective quality, but I was wondering if GMC could improve/save bits in credits encoding, taking into account that credits are a constant vertical-panning scene.

I haven't tested yet but... any idea/opinion?
:thanks:

[Sagittaire]

Make the test and done the result. Anyway I think that use zone option with higher average quant for credit is a very better way for save bits ...

[Blue_MiSfit]

definately. GMC is a fantastic idea but offers little to no compression gain and is SLOW AS BALLS to encode and decode.

Especially laughable is the fact that DivX IIRC uses 1 warp point GMC which essentially does nothing :)

Make a zone and encode it at Q20, feel the love of <500b frames :D :D :D

~MiSfit

[Manao]

But GMC 1-point isn't slow at all ( XviD's 3 points is slow though ). However, it doesn't help that much. On vertical credits, GMC would allow to save 1 bit per macroblock, on pframes ( that is if the credits scroll perfectly vertically and if the codec finds the GMC parameters correctly ). On credits you can generally use up to 2 bframes, so with a classic 640x352 video @ 25 fps, you'd save (25/3) * (640*352/256) bps, ie 7.3 kbit/s.

[numaios]

OK! Thank you for your answers.