Cropping question

[killerteengohan]

Usually I'm always cropping off even numbers from all 4 sides if they ever need it to get rid of black bars. Even the programs I use auto select multiple of 2.

Would it hurt anything if I cropped 21 off the top and 21 off the bottom as long as the total of the top and bottom is an even number? in this case 42?

It wont let me crop by an odd number. Says YUV image can only be cropped by mod 2.

[poisondeathray]

If source is YV12 4:2:0, you can't crop by odd numbers by normal methods

You can get around that and crop by odd values by using the internal crop resizer by specifying src_left, src_top, src_width, src_height

http://avisynth.nl/index.php/Resize

eg. lets say source is 1920x1080, and you want to crop 21 off top, and bottom each

spline36resize(last.width, last.height-42, src_top=21, src_height=-21)

[ndjamena]

Are you resizing afterwards?

YV12 chroma samples are 2x2 luma samples in size, it's the chroma that needs to be cropped to even numbers (relative to luma), there's no way around that short of switching to yv24 or RGB.

[poisondeathray]

Are you resizing afterwards?

YV12 chroma samples are 2x2 luma samples in size, it's the chroma that needs to be cropped to even numbers (relative to luma), there's no way around that short of switching to yv24 or RGB.

You can use the avisynth internal crop resizer and stay in YV12 . Quality is worse if you convert to yv24 (and especially RGB), because you have control over separate dimensions when you use the crop resizer

e.g. see this thread , post #4
https://forum.videohelp.com/threads/368265-ConvertToYV24-Pros-and-Cons

[jagabo]

eg. lets say source is 1920x1080, and you want to crop 21 off top, and bottom each

spline36resize(last.width, last.height-42, src_top=21, src_height=-21)

Note that this will blur the chroma channels a little bit. I'd recommend agaist it if not absolutely necessary.

[poisondeathray]

eg. lets say source is 1920x1080, and you want to crop 21 off top, and bottom each

spline36resize(last.width, last.height-42, src_top=21, src_height=-21)

Note that this will blur the chroma channels a little bit. I'd recommend agaist it if not absolutely necessary.

For sure, it's always better to crop by 2 in YV12 .

[killerteengohan]

Thanks, I just ended up cropping 22 from the top and bottom and taking 2 off left and right to keep the image from stretching up and down. Its better than blurring or going through conversion hassles.

[Damiano]

I have a similar question but more with regards to 'blurring'. I really want to use internal resizer cropping simply because I don't like the fact I overcrop 2 pixel rows for nothing using crop() function, but apparently doing it the other way isn't exactly safe either. Does this 'blurring' thing hold true for other resize methods too?