[Python] how to insert 64 bytes FF to a flash file every 2048 bytes with python

I have a flash file (binary) that is part of firmware.i. I want to program it with programmer to 2GiB NAND flash and must add 64 bytes FF to every 2048 bytes of flash file (like oob). How can I add this 64 bytes with Python or other script. I was able to delete oob section from dump file with Python but can't find any script to add oob to flash file. How can I do this?

I want convert this binary file:

000000 : 12 23 4E 33 7D 66 88 XX XX XX XX XX XX XX XX XX
000010 : 4E 7A 00 23 45 44 4D 54 XX XX XX XX XX XX XX XX
...
0007F0 : 12 22 64 52 17 4E 54 98 XX XX XX XX XX XX XX XX (2048 BYTES)
000800 : 67 8E 43 81 09 75 23 65 14 XX XX XX XX XX XX XX
000810 : 54 22 12 89 45 90 4F 42 56 67 XX XX XX XX XX XX
...
001000 : 76 55 55 33 22 1D XX XX XX XX XX XX XX XX XX XX
001010 : 45 12 08 55 XX XX XX XX XX XX XX XX XX XX XX XX


To this binary file:

000000 : 12 23 4E 33 7D 66 88 XX XX XX XX XX XX XX XX XX
000010 : 4E 7A 00 23 45 44 4D 54 XX XX XX XX XX XX XX XX
...
0007F0 : 12 22 64 52 17 4E 54 98 XX XX XX XX XX XX XX XX after (2048 BYTES)
000800 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
000810 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ADD THIS 64 BYTES (FF)
000820 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
000830 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
000840 : 67 8E 43 81 09 75 23 65 14 XX XX XX XX XX XX XX
000850 : 54 22 12 89 45 90 4F 42 56 67 XX XX XX XX XX XX
...
001030 : 76 55 55 33 22 1D XX XX XX XX XX XX XX XX XX XX after (4096 BYTES)
001040 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
001050 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ADD THIS 64 BYTES (FF)
001060 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
001070 : FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
001080 : 45 12 08 55 XX XX XX XX XX XX XX XX XX XX XX XX
...
8400000 :xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx

Continue reading...