Newbie questions again

[Tiger__Style]

Hi...

I have a few newb questions for anyone who can answer:


What's the difference between demux & decode audio in DVD2AVI?


DivX 5.0.5 Codec settings:
What effect does Quarter Pixel, GMC & Bidirectional Encoding have on the final movie?
And WHEN should i use these options?

I read somewhere that the max keyframe interval should be different on PAL than the default 300 on NTSC.
Why and what should it be?

What does the scene change threshold & Pre processing source do?

Thanks in advance

[SKD_Tech]

Demux - Just extracts the audio
Decode - Extracts and Decodes the Dolby Digital

[UncasMS]

What's the difference between demux & decode audio in DVD2AVI?

demuxing means extracting existing streams as they come - nothing will be changed with those streams.

decoding means a conversion from e.g. dolby digital 5.1 ac3 to a wave file.

deCODING should NOT be used with dvd2avi
always extreact the streams and use tools like besweet for the conversion of the ac3 8or sometimes pcm wave) files

bi-directional encoding should be active when you want better compression (if the material is saturated and UNDERsized, dont use b-frames!), as it improves quality when going for smaller file size.

quarter pixel and global motion compensation is something i DONT use.
with gmc on i found more mosquito noise in my files and of course speed reduction.
and qpel only seemed to reduce speed but did not give me any visible improvements.

max keyframe interval are recommended to be some 10x of the source fps.

pal is 25 thus a value of 250 might be fine.

pre-processing is some sort of noise-filtering.
never used since i prefer other filters for that - CONVOLUTION3D

[Tiger__Style]

Thanks both!

You've been very helpful