Tech q: how is bitsetting achieved - firmware or chip?



I wondered whether anyone’s who modded a firmware knows the answer - does a firmware mod to enable bitsetting perform this setting directly from within the firmware code, or is this mod being done entirely within the controller chip (and the firmware is like an interface/handler)? I am wondering about this since the booktype setting is in the lead-in area, so if it’s possible to access that with firmware perhaps other lead-in area values can be accessed using firmware only.



I answered here:


Reading a single byte from a disc requires a lot of complicated tasks,
and there’s no way this could be hardwired in chipsets. Firmwares
have complete control on the motor, OPU, sledge etc and can therefore
read and write anything they like (for instance a modified firmware can
very well copy CSS keys to a blank DVD+R).


Thanks for your replies.

Actually I ask about this precisely for the reason (example) you indicated, which is to try to create a CSS-encrypted DVD (for a legitimate project I am working on). I figured if the bitsetting could be written, then it might be worth trying to investigate how to set the region code in the lead-in (as a first experimental step), then try to step up to CSS keys. But I recently realised that this is only half the solution, I think it’s necessary to write data into CPR_MAI which I think is not possible - or extremely difficult - due to the current 2048 byte user data writing limitation…

I realise that CSS/region code is defeatable, but I have a need to realise this for writeable DVD - if you have any suggestion or experience relating to this please feel free to PM or email me. Thanks.


The 2048 bytes limitation exists only at MMC level, afterwards it depends
on the drive itself. And all chipsets I know support a way to write user
defined CPR_MAI fields, thus a custom firmware can allow you to do so.
Of course, you would need a perfect knowledge of the chipset and the
firmware to be able to add this feature.


A question … does such firmware already exist? CSS sounds interesting :stuck_out_tongue: