how to make an anamorphic dvd from a 4:3 matted picture

[jaay]

there must be a way to do this, to take a letterbox 4:3 film, remove the borders and make an anamorphic dvd? any ideas?

[jdobbs]

The math is:

16:9 = 1.7777:1
4:3 = 1.3333:1

So you must change the size by (1.7777/1.3333) which comes out to 1.3333:1. 480 x 1.3333 rounds to 640.

So you increase the vertical size to 640 and crop to 480.

It's really easy with AVISynth... All you have to do is resize the vertical axis. Use the script below, it will take a letterboxed 4:3 and make it an anamorphic 16:9. Quality note: When increasing any size always use BicubicResize...

LoadPlugin("C:\PROGRAM FILES\DVD-RIP\AVISYNTH\MPEG2DEC.DLL")
mpeg2source("d:\location\infile.d2v")
BicubicResize(720,640)
crop(0,80,720,480)
ResampleAudio(44100)

jdobbs

[jaay]

thanx for the reply only two questions:
1) that is ntsc i presume
2) where did the 640 for the res come from i thought ntsc was 720x480 - or is this to account for the anamorphic nature?

[StephLG]

Hi jaay,

yes, jdobbs took an NTSC movie format for his explanation.

To convert a 4:3 movie to 16:9, you have to strech it verticaly when you encode it and the player will strech it horizontaly during playback to obtain the correct aspect ratio.

Saying we have a NTSC 720x480 4:3 movie,
1- you first strech it verticaly with the BicubicResize; Final_height = Original_height x 1.777/1.333 => 480 becomes 640
2- you crop the obtained movie at top and bottom to go back to 480 => you remove 2 x 80 pixels with the command Crop(0,80,720,480).

NB: your original 4:3 movie has to be letterboxed otherwize you'll lose information at top and bottom since we cut 2 x 80 pixels to encode the movie at a regular 720x480 NTSC format.

[jdobbs]

StephLG,

Thanks. Absolutely correct. Below would be the PAL equivalent. You'd start with 720x576....

LoadPlugin("C:\PROGRAM FILES\DVD-RIP\AVISYNTH\MPEG2DEC.DLL")
mpeg2source("d:\location\infile.d2v")
BicubicResize(720,768)
crop(0,96,720,576)
ResampleAudio(44100)

As a reminder, the last line (Resample(44100)) is only there due to a bug in CCE -- you'd actually keep your original audio at the 48Khz sample rate.

jdobbs