newbie resolution questions

[gahz]

my source is 1080. auto crop takes 140 off the top and bottom.

does this mean that my final encode will not be 1080 anymore?

i'm using avisynth with crop to mod 16 on anamorphic.

i want my final video to be at 1080 resolution.

[CWR03]

my source is 1080.
1080 what? Resolutions are some number x some number.

does this mean that my final encode will not be 1080 anymore?

i'm using avisynth with crop to mod 16 on anamorphic.

i want my final video to be at 1080 resolution.
Then don't crop.

[LoRd_MuldeR]

I think "1080" means "1080p", which commonly refers to 1920x1080.

However if you want to crop and keep the resolution, there is only one way to do this:
First crop the source and then resize the result back to 1920x1080.

But it's better to crop to a mod16 resolution and keep it that way -or- do not crop at all.
I wouldn't do crop+resize, unless I need to resize anyway...

[salehin]

In addition to what L_M, said: when you're doing cropping, alway make sure you're keeping the aspect ratio closest to the original aspect ratio- here you must calculate it without the blackbars- both for source and encode.

Somewhat related (http://www.highdefdigest.com/news/show/764)

[LoRd_MuldeR]

Usually you don't need to worry about the "aspect ratio" when cropping. Cropping won't change the PAR at all, but it may change the DAR of course.
But as long as your player calculates the DAR properly from the resolution and the PAR, there will be no problem...

For example if you crop away the black borders from a letterboxed 4:3 widescreen video, it won't be 4:3 anymore afterwards (but maybe ~16:9). And that is correct!

[gahz]

ok yes my source is 1920x1080. the crop takes away 140 from top and bottom. so what you guys are saying is that after i encode, my movie is not 1080 anymore? reason i ask is cause i figured since my player adds the black borders back then the total resolution would still be 1080. this is all too confusing to me.

i do use the "crop to mod16" setting.

*edit* actually how do i resize if you guys are telling me i have to resize in order to keep my 1080p resolution after a crop? when i click on the anamorphic check box the resizing option is grayed out in avisynth.

[LoRd_MuldeR]

ok yes my source is 1920x1080. the crop takes away 140 from top and bottom. so what you guys are saying is that after i encode, my movie is not 1080 anymore? reason i ask is cause i figured since my player adds the black borders back then the total resolution would still be 1080. this is all too confusing to me.

i do use the "crop to mod16" setting.

Yes, after cropping away 140 pixels from 1920x1080 (16:9), it will be 1920x940. Obviously. (BTW: That is not mod16, 1920x944 is)

After crop it won't be exactly 16:9 anymore (obvisouly), so when watching it on a 16:9 screen there will be black border added.
These black borders are not in the video, as they were before the crop, but the player/screen will add them at playback time.
And also these black borders are correct, because if the source had black border, the actual movie simply wasn't 16:9 exactly.

Of course you can crop from 1920x1080 to 1920x940 and then resize to 1920x1080, in order to get rid of the black borders on a 16:9 screen.
However resizing unavoidably cause a certain amount of detail loss. Also the video will look stretched (slightly) after the resize!

You can also crop it down to 1680x944 in order to preserve the 16:9 aspect without any "stretching", but you loose some part of the image...

*edit* actually how do i resize

Lanczos4Resize(1920,1080)

[gahz]

Yes, after cropping away 140 pixels from 1920x1080 (16:9), it will be 1920x940. Obviously. (BTW: That is not mod16, 1920x944 is)

actually it's cropping 140 from the top and bottom so it's at x800 not x940 if that makes any diff.

After crop it won't be exactly 16:9 anymore (obvisouly), so when watching it on a 16:9 screen there will be black border added.
These black borders are not in the video, as they were before the crop, but the player/screen will add them at playback time.
And also these black borders are correct, because if the source had black border, the actual movie simply wasn't 16:9 exactly.

Of course you can crop from 1920x1080 to 1920x940 and then resize to 1920x1080, in order to get rid of the black borders on a 16:9 screen.
However resizing unavoidably cause a certain amount of detail loss. Also the video will look stretched (slightly) after the resize!

You can also crop it down to 1680x944 in order to preserve the 16:9 aspect without any "stretching", but you loose some part of the image...

yea that's kinda what i'm asking i think. are people resizing after the crop when they want to preserve the 1080 resolution? i know most drop it down to 720 but for those that do want to keep 1080 is the only answer to resize after the crop?

Lanczos4Resize(1920,1080)

can i ask why the resizer is grayed out if you click on anamorphic check box in avisynth?

[LoRd_MuldeR]

actually it's cropping 140 from the top and bottom so it's at x800 not x940 if that makes any diff.

No, it doesn't make any difference. The facts remain the same.

are people resizing after the crop when they want to preserve the 1080 resolution?

No, why should they?

Resizing unavoidably kills some amount of details. Also cropping vertically only and then resizing back to the original resolution will produce a "stretched" image. You don't want that! As said before: 1920x1080 (aka 1080p) is a 16:9 resolution. However if you crop a 16:9 video vertically only (that is: on top/bottom only), it won't be 16:9 anymore. Obviosuly! Hence any "correct" resolution for that video won't be 16:9 any longer. 1080p is invalid for the cropped video! So just crop away the black borders and keep the resulting resolution as-is ...

can i ask why the resizer is grayed out if you click on anamorphic check box in avisynth?

Avisynth is a scripting language. You edit it in your favorite text/code editor. How can there be aynthing "grayed" out ????

[CWR03]

i know most drop it down to 720 but for those that do want to keep 1080 is the only answer to resize after the crop?
Does the 1920 x 1080 video display correctly with black borders intact? If so, don't crop. The borders in the video won't have enough effect on the required bitrate to warrant cropping, and cropping can lead to playback issues.

You have asked three times now how to keep "1080." If you crop, you can't.

[LoRd_MuldeR]

If he really insists on completely filling his 16:9 screen with his none-16:9 movie, he could crop vertically and horizontally.
The result again would not be 1080p (unless additional resizing is applied) and he will also loose a significant part of the image...

[gahz]

ok the reason i even ask these questions is because i was having a debate with a friend of mine over this. On a 1080 display, if i play the bluray there are still black borders. Now I figured that these black borders on this particular movie took up 140 pixels at top and 140 pixels at the bottom. If you add it all up it equals 1080 lines right?

Now here is where i get confused. When I crop those black borders my resulting video is now 800 vertical lines, but when I play it on the display the black borders are then added again at top and bottom totalling to again 1080 lines.

So wouldn't both examples there mean that they are both displaying 1080? Sorry for the confusion.

[CWR03]

The black bars aren't added. They're just black areas where there is no video. The file is displaying at the proper aspect ratio, otherwise it would stretch to fill the screen and wouldn't look right, but once you crop the black bars you no longer have a file that is "1080." If it displays properly, then it doesn't matter whether you crop or not, but to "future-proof" you might leave the full 1920 x 1080 intact.

[gahz]

Avisynth is a scripting language. You edit it in your favorite text/code editor. How can there be aynthing "grayed" out ????

i'm sorry, i meant the avisynth gui thing that comes with megui.

The black bars aren't added. They're just black areas where there is no video. The file is displaying at the proper aspect ratio, otherwise it would stretch to fill the screen and wouldn't look right, but once you crop the black bars you no longer have a file that is "1080."

i gather from this that a bluray being displayed at 1080 is including the black bars? that makes more sense now because i was led to believe before that it was the movie frame only that comprised all 1080 lines not movie + black bars. thank you for clarifying this.

[CWR03]

I see the confusion now. As far as I'm aware, all Blu-Ray video is 1920 x 1080, and if there are black bars displayed, they are part of the "1080" video. Now if you crop them, your new file will be 1920 x 800, but since the movie frame height is not changed the movie will display the same as if it were still 1080 in height. Again, though, there's no real reason to crop, and some day there may be standalones that will play a 1920 x 1080 file and display it properly. When people first started backing up their DVD material and later bought DivX-certified players, they were in a tizzy because their files weren't playing at the proper AR, because they'd cropped the black bars and the player was stretching the video to fill the screen...

[LoRd_MuldeR]

i gather from this that a bluray being displayed at 1080 is including the black bars? that makes more sense now because i was led to believe before that it was the movie frame only that comprised all 1080 lines not movie + black bars. thank you for clarifying this.

If BlueRay requires a resolution of 1920x1080, which obviously is 16:9, but the movie itself is not 16:9, what else should they do than including black bars in the video stream???

Stretching the movie to the 16:9 aspect to make it look ugly? Cutting it down to 16:9 and loose a big part of the movie? You don't want any of this ;)


Now here is where i get confused. When I crop those black borders my resulting video is now 800 vertical lines, but when I play it on the display the black borders are then added again at top and bottom totalling to again 1080 lines.

Because your screen doesn't shrink to 800 lines all of a sudden :p

Your screen is still 16:9, the movie isn't 16:9 anymore after the cropping. Before the cropping the video was 16:9, because of the black bars in the video.
Consequently the screen (or the player) will fill the "missing" lines with black bars again, in order to make it fit on the screen and display correctly.

You wouldn't want your player/screen to stretch the none-16:9 video to 16:9, unless you like egg heads....