How to make a DVD comparison

Film Reviews and Release Comparisons
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bradavon
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How to make a DVD comparison

Unread post by bradavon » 08 Sep 2006, 19:16

Optimal PowerDVD settings:
tom wrote:Configuration -> Video = Deactivate hardware acceleration (your GFX card won't interfere with video quality).
Use color profile -> Original.
Video -> Advanced -> Deactivate deinterlacing.
Video -> Advanced -> Color -> All settings to zero.
Player -> Advanced -> Snapshot -> Capture to clipboard / custom size = 1024x576 (Anamorphic) 768x576 (4:3 or Non-Anamorphic/Letterbox).
tom wrote:If you have to choose between two types of deinterlacing (Bob / Weave), choose "Weave".

Blend: Evil.
The first half-frame (or field) is blended with the second field.
It will look good as long as there's no movement.
Any movement will create ghosting.

Bob: Good.
Every field is displayed separately, one after the other.
But you'll lose half the vertical resolution.

Field Shift: I don't really know.
Top fields become Bottom fields.
Bottom fields become Top fields.
I don't know what good it can do.
Easy Alternative method for taking caps (and more accurate, no filtering by PowerDVD or MPC):
Lourdes wrote:Download and install DVD43 unless you already use software such as AnyDVD or CSS Free.

Download and extract This File anywhere.

Run "VirtualDubMod.exe" and open a .vob file from the VIDEO_TS folder on the DVD. It may take some trial and error to find the VOB you want but generally the fist 1GB file on the disc should be the first part of a film.

Find whatever you want to cap using the slider and then the << >> buttons or arrow keys on your keyboard for frame-by-frame movement. It's advisable to use the first or last frame of a shot to make it easier to match caps up.

Go to "Video > Snapshot source frame" or hit "Shift+1" to save the cap. It doesn't matter what filetype you use but save the caps as 1-10 or 01-10 in the directory you extracted.

Now if the DVD is anamorphic run "16x9.bat" or if it is fullscreen/letterboxed run "4x3.bat".

Upload the .jpg files that were just produced.
How to include the Average DVD Bitrate of each DVD:
Download Bitrate Viewer from this website: http://www.remoteselector.com/download.htm

It's a tiny 7.50Kb download and has no Setup routine. With the DVD in your DVD Drive run the software and it will tell you the average bitrate in the title bar.

Include this in your comparison for each DVD.
Last edited by bradavon on 26 Oct 2007, 19:25, edited 6 times in total.

tom2681
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Unread post by tom2681 » 10 Oct 2006, 15:01

How to choose the right screencaps:

You need between 4 and 6 caps. Make sure they are in chronological order (makes them easier to find).
- A dark cap (to compare shadow detail).
- A bright cap (to compare contrast boosting).
- A cap with lots of detail and colours.
- A moving frame.
- A subtitle sample.
Last edited by tom2681 on 24 Nov 2006, 17:32, edited 2 times in total.
I used to be "the man who loves the movies you hate".
Now I'm just "that weird french guy with a cat avatar who comes to BnB once a year for no reason and then disappears again".

tom2681
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Unread post by tom2681 » 12 Oct 2006, 15:42

How to analyze screencaps properly:

Contrast Boosting:

Contrast boosting can be seen as a loss of detail in white areas.

Image

Image

The second cap looks better, but it's not. The contrast boosting makes some of the curtains disappear.

Combing:

Combing comes from viewing interlaced transfers on progressive displays (PC monitors or Videoprojectors).
It can be seen as thin black lines, only visible during motion.

Image

Image

This sort of comparison is quite unfair, since these lines won't appear at all on your display, as most displays can make them disappear using various deinterlacing modes.

Edge Enhancement:

EE is a filter that is applied on a transfer to make it look sharper on smaller screens.
It doesn't create any detail. Just the illusion of sharpness.
EE can be seen as a white halo surrounding the edge of sharp objects.

Image

Image

The second cap looks sharper but it's not.
Both caps feature the exact same amount of detail.

Note the big white halos surrounding Aya's cape.

What is interlaced ?
What is progressive ?


Film is shot at 24 full frames per second.
Those frames are called progressive.

TVs display 60 half-frames per second in the US.
They display 50 half-frames per second in the UK.

These displays are called "interlaced displays".

An interlaced picture looks like this:

Image

Those thin black bars are called "combing".
You see combing because your monitor is displaying two half-frames.

What about DVDs, now ?
DVDs can be either:
-progressive (24 full frames per second).
-interlaced (60 half frames per second).

How to recognize an interlaced DVD on your PC ?
If you're using PowerDVD, you need to deactivate deinterlacing.
(Configuration -> Video -> Advanced, I think).
Then, play a bit of the film (scenes with fast motion, preferably).

If you see this:

Image

Then the DVD is progressive.

If you see this:

Image

Then the DVD is interlaced.

Progressive DVDs are always better, because in order to remove the combing, you need to use deinterlacing. And deinterlacing can produce "ghosting", like this:

Image

In some rare cases, ghosting can be seen even when Deinterlacing is deactivated.
It means that the ghosting comes from the transfer itself (poorly done NTSC -> PAL conversion for example).


Note: I know that some of the info above is inaccurate. I've simplified it on purpose to make it easier to understand.

Horizontal and Vertical stretching:

Most of the time, the horizontal stretching of a transfer is a direct result of cropping.
If you crop the sides by 6%, you have to stretch the picture by 6% to keep the aspect ratio.

Image

Image

First cap is cropped and stretched. Second cap isn't.

Vertical stretching is quite rare.
You can find it on HKL's Magnificent Butcher, and on several korean DVDs (they sometimes stretch 1:85 transfers to 1:778 instead of cropping them).
I used to be "the man who loves the movies you hate".
Now I'm just "that weird french guy with a cat avatar who comes to BnB once a year for no reason and then disappears again".

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