2.35:1 inside 4:3 -> 16:9 - need to resize after crop?

[Mr.Bitey]

Howdy,

Im trying to convert my R4 (PAL) copy of The Abyss Special Edition, which unfortunalty only came out in 2.35:1 within a 4:3 AR - which on a 16:9 display you get a postage-stamp picture with black borders top/bottom/left/right.

I used crop to remove the top and bottom black borders, and added new borders to maintain the 2.35:1 AR. This looks fine on my 16:9 display now, with no black borders right/left and an image that is in the correct AR and takes up the full width of my display.

My question is, should I be doing a resize after the first crop? im not fully understanding how the image is getting from a postage-stamp to a larger image :-)

Cheers,
Bitey

[IanB]

The original case sound like a case of the irritating letterbox+pillarbox.

Letterboxing is adding borders top and bottom to keep the AR correct. Examples are 16:9 and 2.35:1 images on a 4:3 display.

Pillarboxing is adding borders left and right to keep the AR correct. Examples are 4:3 images on a 16:9 display.

Typically when a 16:9 display device is presented with a 4:3 image it will pillarbox. It could alternativly crop the top and bottom or a combinations eg 14:9 as favoured by our ABC network.

So in your case you have a 2.35:1 movie hard letterboxed to 4:3. You display the 4:3 image on your 16:9 device and it gets pillerboxed. Together the result is ironicly a postage stamp :D

Upmarket devices usually have a zoom function to correct this.

[Mr.Bitey]

Hiya Ian,

I can zoom (im viewing using zoomplayer), but the resulting 'zoomed' image looked very poor - like I could see scan lines/interlaced :-)

I ran it through the following script:

MPEGSource("D:\DVDIMAGE1\1\VIDEO_TS\abyss.M2V")
crop(0,126,720,324)
Addborders(0,72,0,72)

This results in a correct 2.35:1 (or very close) AR image on my 16:9 display using the full width. Im getting a much larger image and am wondering how the image is getting resized?! and should I be adding in a resize function?

Cheers,
Bitey

[IanB]

If you are just viewing the .avs file you could skip the addborders by adjusting the crop to Crop(0, 54, 720, 468). If you are transcoding then what you are doing is best, it ensures the letterbox area is pure black.

The good resizing is probably happening courtesy of the video overlay. Most video cards do a good job of scaling the overlay data to fit on the allocated screen area.

Using the player internal zoom is probably using a crappy point resizing algorithm (because it is very fast).

[MrTroy]

Looking at your 720x324 resolution, it seems your movie actually has the 2.37:1 ratio.

With square pixels, 2.37:1 on a PAL DVD has a resolution of 1024x432. With nonsquare pixels this becomes 720x432. A correct Avisynth script would be:

MPEGSource("D:\DVDIMAGE1\1\VIDEO_TS\abyss.M2V")
Crop(0,126,720,324)
BilinearResize(720,432)
AddBorders(0,72,0,72)

(you can of course replace BilinearResize with any resizer you like)

[edit] I completely changed my post, I made a mistake with the resolution. It's fixed now.

[Mr.Bitey]

IanB, Thanks for the explination :) - I am feeding the avs script into into CCE

MrTroy, Thanks for the explination & script, I see what its doing now :)

If i may pose another noobish question :)

If I add a denoiser after the crop, such as hqdn3d (the source is a bit noisey) then feed the avs into cce multipass (eg 4 passes) - will hqdn3d get run on each pass or just on the intitial pass? - eg. will it get denoised 4 times?

Cheers,
Bitey

[Robo210]

When you run a script through multiple passes, the entire script is run each and every time. This does not mean that the results of one pass are fed into the next pass, but rather each pass will result in identical output for the encoder to study. If your script is going to take a long time to run, and you are going to be running it many times, a shortcut would be to first encode the script to a lossless format such as Huffy, then feed this into cce or whatever. This way the script is run only once.

[Mr.Bitey]

Hi Robo210,

Thanks :-) thats cleared it up!

Cheers,
Bitey

[Boulder]

For easy cropping and resizing (and doing these 4:3->16:9 conversions), I can highly recommend trying PARanoia out.

(Btw, for upsizing, try some other resizer than bilinear. Lanczos might be better suited for the job.)

http://sourceforge.net/projects/paranoia-