Some basic question(avi's,progressive/interlaced,colorspaces)? Anyone PLZ!

[redBeanz]

Ok, basically I have been reading forums and tutorials for like ever. I have some questions that I still haven't fiqured out yet. I would greatly appreciate anyones input. Thnxs.

1) How do I tell if an .avi file is interlaced or progressive?
(For .mpg's I use bitrateviewer)
a)If my .avi is progressive should I convert to interlaced? I
am converting to mpeg-2 to write to DVDR. If so how do I do this?

2) I have an .avi with lots of "interlace artifacts", when converting
to mpeg-2 for DVDR purposes, how do I fix it?

3) What kind of things should I be thinking about when converting
.avi's or svcd to dvdr, to MAXIMIZE video quality?

4) What are color spaces (i.e. YUV2 and RGB)? and Why are they
important?

These are all the ?'s I have for now. Thnxs.

[avih]

1. you play the file and watch some hi-action scenes. if you see interlacing artefacts, then... it's interlaced ;) with time you'll be able to tell if a clip is interlaced by watching it playing for few seconds.

1.a. no need to convert it to interlaced. the standards you mentioned support both interlaced and progressive contents. converting it to interlaced is done by the player hardware/software while playing.

2. if you are going to watch it on tv, then there's no need to de-interlace it ("fix"), since the tv displays interlaced content natively and without artefacts. furthermore, de-interlacing will probably harm the overall quality of the clip since it'll probably remove some temporal data.

3. nothing really. just follow the general guidelines for composing a dvd/svcd. one thing you should pay attention to is the field order in case the clip is interlaced.

4. color spaces are the different kinds of binary representation of the uncompressed image. the colorspace define the structure of the image in memory, and more importantly, the relation between the color components to the 'bare-bones' black and white image. the most important difference among color spaces is the number of black-and-white pixels covered by a single color component.

examples:
RGB: each b/w pixel is assigned with it's own color component (metaphorically speaking).
YUY2 (and others): each 2 b/w pixels are assigned with a single color component.
YV12: each 4 b/w pixels are assigned with a single color components.

as a result of the above differences, images represented in different colorspaces will consume variable amount of memory, and will have variable degrees of 'color resolution'.

codecs and video standards (DVD, SVCD etc) work usually with a single colorspace, therefore colorspaces conversions have to take place.

colorspace conversions are usually somewhat lossy. especially if it's done from one with high color resolution to one with low color resolution.

[redBeanz]

Thanks for your reply avih. Your explanation of color spaces was a bit technical for me but it's ok, I probably have to do some more reading, your explanation is a good start. I have some more questions if you don't mind.

1) So when converting to DVDr should I be concerned with what color space my input source uses? Is there a standard color space for DVD?

2) This is a really general question but, what about avisynth scripts? I was thinking about really trying to learn the "API"(its various functions), but I mean what can I get out of it other than say resizing the image/(movie?) or changing the frame rate? I mostly dl movies (avi's and mpeg) and convert then burn to DVDr.

[avih]

redBeanz, i think it's time you start search the forums and read some manuals and faqs. you had a nice jump start, but you'll learn much more thoroughlly by reading and trying out stuff yourself.

cheers
avih