Crop HD frame out of 4K and directly create new HD from it

[caphow]

Hi,

would like to crop an exact 1920x1080 frame out of 4K footage. The frame to be placed around an object; could be situated anywhere within the 4K. Then create an HD footage with exactly those cropped pixels. Then save as a sub clip. Do so with several original 4Ks and then composite in timeline.

Also like to follow the object, as it moves through the footage.

Thank you very much in advance.

[Jeff Bugbee]

You might want to do this in After Effects. Create a 1920x1080 black still (set to 50% opacity), animate it to follow your object. You can then track and crop the 1920x1080 frame and export back to Premiere.

[caphow]

Thank you Jeff Bugbee. I will try and report how it worked.

[excited_Genie16B8 · Accepted solution]

Put the 4k clip into an HD sequence, keyframe position as needed.  Export.  Repeat.

[caphow]

Thank you Jim Simon. I will try and report how it worked.

[caphow]

Thank you both Jim Simon and Jeff Bugbee. Both answers helped me a lot, since I am new to Pr and Ae. Both were correct. I just can't mark both as correct answers in the system, as it seems.

This is what worked for objects in 4K to be extracted into HD:

Case 1 fixed crop around fixed object: As Jim pointed out, create an HD sequence. Place the 4K into it. Move the 4K footage around, until it is "captures" the object (Effects: "Motion"). Export as needed (sub-clip or final export).

Case 2 moving crop to follow moving object: Use motion tracking as Jeff pointed out. Ae seems to be the best choice for this.

Thank you both! Your input is much appreciated!