Scene Change Detection could use some attention

[int 21h]

Currently it catches quick scene changes and cutaways good. It seems to rarely catch fade ins and fade outs (just watch the Vdub graph as it encodes, the framesize goes down, then goes back up as it fades to another shot, but no keyframe is inserted :(), this results in reduced quality during a long period of fade ins and fade outs (i.e. opening sequences like in Edward Scissorhands).

[kilg0r3]

i'd also opt for a possibility to adjust xvid's sensibility regarding the scene change threshold since the mechanism in the virualdub does not seem to have any effect; for mem at least.

[TripleA]

It would be nice if that got fixed, yes.

But, I'd settle for a way to force key frames, in the meantime...

[zettai]

Why do you want keyframes on fades? There doesnt seem to be much point in that.

Fades are great for compression, sticking a keyframe in there would be a waste of space, right?

[kilg0r3]

@zettai

if the movie merely fades to black you are right. but if you have a crossfade going from one image to an entirly different one or even some more a key frames would probably be nice.

yet, it might be a good idea to put only one at the end of the crossfade in order to get the best reference basis for the following images. hm ... the position of the key frame might be something which needs to be determined by testing.

[int 21h]

Originally posted by zettai
Why do you want keyframes on fades? There doesnt seem to be much point in that.

Fades are great for compression, sticking a keyframe in there would be a waste of space, right?

Encode the first 5 minutes of a fading movie, I imagine any weird Tim Burton flick is a good example. When you don't have a keyframe and the scene fades to black, you can be left with visible artifacts after the fade. The same goes for when it fades from one object to another.

In general, having such long periods of movement and no keyframes is bad :( It degrades the quality more than just using that small bit of space and putting a keyframe in. (Hence the addition of the scene fade code in Nandub around b12 or so.)