Resolution Question

[killerteengohan]

On the back of my DVD Case it says it is 16x9 Widescreen and then right next to it, it says 1.85:1

To my understanding 16x9 was 1.78:1 aspect ratio, yet the DVD case says 1.85:1 right after the 16x9 widescreen.

So which one is it? which one should I go by? Which resolution should I make the encode?

[jagabo]

The movie is 1.85:1. The DVD is 1.78:1 (16:9). DVD only supports two aspect ratios: 4:3 and 16:9. Any other movie aspect ratio will either be cropped or letterboxed to fit within those aspect ratios. So that movie fills about 720x464 pixels of the 720x480 frame on the DVD if NTSC. If PAL it fills about 720x554 of the 720x576 frame.

[killerteengohan]

The movie is 1.85:1. The DVD is 1.78:1 (16:9). DVD only supports two aspect ratios: 4:3 and 16:9. Any other movie aspect ratio will either be cropped or letterboxed within those frame sizes.

Im not sure which one your telling me to go by. All I get out of that reply is info I mostly already knew.

so do I go with the 1.85:1 and just crop off black bars? what resolution is that? 720x404?

[edDV]

The movie is 1.85:1. The DVD is 1.78:1 (16:9). DVD only supports two aspect ratios: 4:3 and 16:9. Any other movie aspect ratio will either be cropped or letterboxed within those frame sizes.

Im not sure which one your telling me to go by. All I get out of that reply is info I mostly already knew.

so do I go with the 1.85:1 and just crop off black bars? what resolution is that?

If you want to make a DVD you use 720x480 (with letterbox). If you want to make a 1.85:1 file you have many choices depending on the pixel width you want.

First, do you understand that DVD pixels are not square?

Is the source DVD "NTSC" 720x480 or "PAL" 720x576?

[killerteengohan]

The movie is 1.85:1. The DVD is 1.78:1 (16:9). DVD only supports two aspect ratios: 4:3 and 16:9. Any other movie aspect ratio will either be cropped or letterboxed within those frame sizes.

Im not sure which one your telling me to go by. All I get out of that reply is info I mostly already knew.

so do I go with the 1.85:1 and just crop off black bars? what resolution is that?

If you want to make a DVD you use 720x480 (with letterbox). If you want to make a 1.85:1 file you have many choices depending on the pixel width you want.

First, do you understand that DVD pixels are not square?

Is the source DVD "NTSC" 720x480 or "PAL" 720x576?

Its NTSC 720x480

I would like to keep 720 width. I usually just do 852x480 or 848x480 since thats what it resizes to during playback but I want it 720xwhatevergoeshere this time.

Im not wanting to make a DVD, Im wanting to encode an AVI or MKV from my DVD.

[guns1inger]

what software are you using ? xvid4psp will autocrop for you, xmedisrecode has an autocrop feature under the crop setting.

[killerteengohan]

what software are you using ? xvid4psp will autocrop for you, xmedisrecode has an autocrop feature under the crop setting.

Ive been using MeGui and avisynth.

[edDV]

Well it gets complicated.

Wide DVD pixel aspect ratio is supposed to be 1.2121 but many DVD authors cheat to around 1.1866. Others crop the frame sides so the active picture is no longer 1.85:1 aspect ratio. The active picture is like a rubber sheet that can be stretched horizontally or vertically.

For progressive film source, vertical resize avoids expansion resize losses. Interlace video (like a TV capture) needs to be deinterlaced before vertical resize.

The quick and dirty method is to crop off the letterbox, measure the remaining vertical lines, then vertically resize until the pixels are square. You can judge whether pixels are square by measuring a large circular object in the film. Or you can simply vertically resize to original film aspect ratio* and check for distortion. If they cropped the sides the rubber sheet will be stretched.

* e.g. 720/1.85 = 389 lines. But for encoding efficiency, you may want mod 8 or mod 16. That means 392 lines (mod 8) with a little letterbox or suffer a slight aspect ratio distortion.

[jagabo]

You could just leave the black bars and encode at 720x480 with 16:9 aspect ratio flags. Who cares if there are a few lines of black bars at the top and bottom? It's going to show up that way on a 16:9 TV anyway. And static black bars require hardly any bitrate -- so they won't be stealing bitrate from the main picture.

If you really must crop the black bars go ahead. That will leave a ~720x464 frame. Use the pixel aspect ratio flag to force the display aspect ratio. Since you're not resizing the remaining image set the pixel aspect ratio to 32:27, just like the original DVD. That way you lose no resolution and don't get any resizing artifacts.

[killerteengohan]

You could just leave the black bars and encode at 720x480 with 16:9 aspect ratio flags. Who cares if there are a few lines of black bars at the top and bottom? It's going to show up that way on a 16:9 TV anyway. And static black bars require hardly any bitrate -- so they won't be stealing bitrate from the main picture.

If you really must crop the black bars go ahead. That will leave a ~720x464 frame. Use the pixel aspect ratio flag to force the display aspect ratio. Since you're not resizing the remaining image set the pixel aspect ratio to 32:27, just like the original DVD. That way you lose no resolution and don't get any resizing artifacts.

Thanks, I got this all handled and finished before I noticed any replies.

There are no black bars on it though, it was stretched up to 480 height for the DVD. Ive never actually added black bars to the top and bottom on my own. I was just asking if I should crop off black bars if there were any.

[jagabo]

The bars would only be 8 scan lines each. If there really are no bars they may have just cropped the frame a little.

[killerteengohan]

The bars would only be 8 scan lines each. If there really are no bars they may have just cropped the frame a little.

The box says 1.85:1 anamorphic and the VOB says

I used mediainfo to get this.


Video
ID : 224 (0xE0)
Format : MPEG Video
Format version : Version 2
Format profile : Main@Main
Format settings, BVOP : Yes
Format settings, Matrix : Default
Bit rate mode : Variable
Bit rate : 9 800 Kbps
Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 fps
Standard : NTSC
Resolution : 8 bits
Colorimetry : 4:2:0
Scan type : Progressive
Scan order : 2:3 Pulldown
Bits/(Pixel*Frame) : 1.183



so does 720x404 sound about right? or 720x390? I plan to leave the black bars on bottom and top so I dont screw up the ratio.

[aedipuss]

if you want 16/9 then it's 720x9/16 if you want 1.85 use 720/1.85 - but, for some formats it's best to round those to the nearest multiple of 16.

that's if you remove the black bars for 1.85. they are permanently encoded to show in 16/9 as that's all dvd spec has. if not going to remove them your only choice is 16/9.

[jagabo]

I would leave the frame as it is, or cut away the black bars, and set the pixel aspect ratio (the shape of individual pixels) to 32:27. That way you avoid resizing and lose no resolution.

If you must resize to square pixels:

If you leave the black bars the exact 16:9 size is 720x405. But most codecs don't like odd frame sizes. 720x404 is the nearest mod 4 size. 720x400 is the nearest mod 16 size.

If you crop the black bars the nearest 1.85:1 frames size is 720x389. Again, most encoders don't like odd frame sizes so 720x388 is the nearest mod 4 frame size, 720x384 is the nearest mod 16 frame size.

[killerteengohan]

Thanks to both of you!!

I just left the black bars and went with 720x404 AVI. If I was doing it in MKV I would have went with 720x400.

It looks fine to me, thanks alot.