ESp32 cam ov2640 manual exposure problems

[Radu79]

I've been playing with this sensor for over a month, and found out many of its 'secrets' (undocumented things), but for the life of me I can't see how to do manual exposure.
I can get really long exposures by playing with the clock dividers, adding pixels to lines and lines to the frame, but I can't get it to obey my exposure time.

The code is really simple:
s->set_reg(s,0xff,0xff,0x01);//banksel
s->set_reg(s,0x13,0xff,0);//manual everything
s->set_reg(s,0x45,0x1f,0x1f);//really long exposure

However, this last line doesn't seem to be doing anything at all. Is there something I am missing?