I updated some of the wording in my original posting making it slightly easier to understand and now that it has been restored I feel comfortable directly posting a copy of it here....
There is now a *hacky* method of doing a safe downgrade for users who don't have the ability to do a backup of their drl files. This method can also be used to fix a ps3 with broken playback if you know the newest disc your ps3 has played.
If you go out and rent Inception(high mkb) and play this in your ps3 before downgrading this spreadsheet will be updated with the hex values of the DRL files to potentially recover your blu ray playback.
https://spreadsheets.google.com/ccc?...en&output=html
The DRL data from inception is now in the spreadsheet, this is a good candidate as it has one of the higher mkb versions. Let's say that The Dark Knight was the highest MKB version that your PS3 has seen, then the below data would be used to restore your playback.
We have found out that the mkb from the title that updated your drl files can be used to restore your playback completely. The MKB data is located inside BD://AACS/MKB_RO.inf; If you use a PC BD drive from windows, mac, linux, etc. You can extract this data. We are working towards a method of doing this from the PS3 directly, but so far it appears GAMEOS may be blocking this file.
If this file is opened in a hex editor the beginning of the file contains the Type and Version record...
ie: 10 00 00 0C 00 04 10 03 00 00 00 09(mkb version in hex) -- The Dark Knight (12 bytes) 0x09 -> MKB9
Then the HRL is listed....
21(HRL) 00 00 6C(record length) 00 00 00 07 00 00 00 07 00 09 FF FF 00 00 00 0B 00 00 FF FF 00 00 00 16 00 08 FF FF 00 00 00 21 00 03 FF FF 00 00 00 35 00 04 FF FF 00 00 00 4E 00 03 FF FF 00 00 00 54 00 03 FF FF 00 00 00 5E 2B 73 F1 7E 29 D4 04 7D 74 84 21 1E 3F 35 42 FE EB 3E B9 B1 63 B9 57 7D 86 AF F4 1A 02 A9 33 61 96 51 5A 67 0A 27 5C 8A -- The Dark Knight (0x6c = 108 bytes)
Following the HRL the actual DRL data begins.
20(DRL) 00 00 34(record length) 00 00 00 00 00 00 00 00 44 8F F5 FA B4 79 A3 FD FC B9 92 01 35 5C 21 3B D9 8C D3 20 06 B0 76 B5 46 92 1E 46 52 16 EE A5 5D 1E 7B 2D 02 C7 6D 0A -- The Dark Knight (0x34 = 52 bytes)
Combining the Type and Version Record with the DRL data gives you the hex contents of the proper DRL1/DRL2 files if this disc was the highest mkb version your ps3 has seen. This is called a Partial MKB.
10 00 00 0C 00 04 10 03 00 00 00 09 20 00 00 34 00 00 00 00 00 00 00 00 44 8F F5 FA B4 79 A3 FD FC B9 92 01 35 5C 21 3B D9 8C D3 20 06 B0 76 B5 46 92 1E 46 52 16 EE A5 5D 1E 7B 2D 02 C7 6D 0A
The above hexed over your broken drl will restore your playback. This isn't surefire if you've played another movie that is higher than inception or have updated your drl with a different movie that is the same mkb as inception. All in all you just need to know which newest disc updated your drl and that will give you the method to restore your playback. Most won’t have to try too many DRL variations until finding the right title.
Others are (0x3c = 60 bytes)
10 00 00 0c 00 04 10 03 00 00 00 13 20 00 00 3c 00 00 00 01 00 00 00 01 03 e7 00 00 00 00 00 01 93 78 15 97 ad d4 32 7b 90 7f 5b b7 f2 b2 e7 99 d9 ee 28 11 8c b5 4a f3 c1 fe 35 56 bd bf 9a db 38 7a 29 49 d4 87 ba 01 -- Inception (0x3c = 60 bytes) 0x13 -> MKB 19
If you have MKB files from titles not on the spreadsheet and aren’t comfortable extracting this data yourself. Add a download link tempfiles, rapidshare, putfile, etc. to the spreadsheet with the movie title and I will grab the data and update the spreadsheet. Also if you find the hex for your title, please update the spreadsheet to help some others who may have used the same movie and don’t have a BD drive or the skills to produce it themselves.