How to crop & save the .raw frames?

[liuxinrui0831]

Hi @6by9. Currently, I'm running raspiraw using IMX219 + Pi 4 Model B to capture frames at 640175 @ 500 Hz. In my application, I only need the central part of the frame, so I would like to know if it is possible to crop the raw frame from 640175 to 175*175 (i.e. drop some pixels on the left and right) before writing it to the disk. If it is possible, could you please tell me how to implement this (i.e. how to change this line of code so that only the central part of the frame is written to the disk)? Besides, to make the cropped frame compatible with dcraw, do I need to change the header for the raw frames?

[6by9]

https://github.com/raspberrypi/raspiraw/blob/master/imx219_modes.h#L34

// These values are copied from
// https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=162722&p=1052339
// Raspberry Pi can not discuss these settings as we have information from
// Sony under NDA.

// REQUESTS FOR SUPPORT ABOUT THESE REGISTER VALUES WILL
// BE IGNORED BY PI TOWERS.