Decided to spend some time investigating how autocorrect works.
All of this was done with Ryu vs Ryu, SSF4AE PS3 with my own PStick setup. Visual analysis for confirmation where needed. Syntax I use is 1PF0 meaning player 1 inputting a motion on frame 0.
First test was fairly simple.
2PF0 uf with 1PF0 d to mark the timing.
If P1 does SRK motion finishing on F18, it will not autocorrect.
If P1 does SRK motion finishing on F19, it will autocorrect.
If P1 does SRK motion finishing on F20, it will not perform SRK.
This matches with the simple jumping motion, where again
If 2PF0 uf with 1PF0 d to mark timing.
If 1P presses u on F18, it will not autocorrect.
If 2P presses u on F19, it will autocorrect.
Further investigation after knockdown
d+HK done on P2F0.
P1 can input u on F87 to jump, earlier inputs ignored.
P1 inputs SRK ending on F87.
If 2P jump is performed on F50, normal SRK will occur.
If 2P jump is performed on F49, autocorrect SRK will occur
If 2P jump is performed on F48, crouching jab will occur.
By performing the entire SRK motion in the buffer window, you can gain one extra autocorrect frame, at the expense of no normal move (crouching jab) coming out.
This was achieved by double hitting d+LP versus d+HK to shorten the recovery time of d+HK, then jumping over versus a fully buffered SRK.
A jump on F47 will result in nothing, a jump on F48 and F49 will give autocorrect SRK and a jump on F50 will give a normal whiffing SRK.