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I've flashed my ASUS SBW-06D5H-U A102 (MT1959 internals) with the BU40N MK 1.03 firmware to enable libredrive features and then tried to rip a BR movie. Though above 2.0x speed, it seems to never go higher than 3.5x during the whole process. The drive is capable of 6x and the BRs are mint condition. Why don't I reach 6x RIP speed like I did with a previous Pioneer drive which was automatically libredrive enabled. Could it be due to the new firmware or is it just a media problem maybe? (Drive info below shows HL-DT-ST instead of ASUS SBW-06D5H-U after the flash)

MakeMKV latest 1.18.4 beta on Windows 11, drive connected via USB C

Drive Information
OS device name: \Device\CdRom1
Current profile: BD-ROM
Manufacturer: HL-DT-ST
Product: BD-RE BU40N
Revision: 1.03
Serial number: xxx
Firmware date: 2118-10-24 19:34
Bus encryption flags: 17
Highest AACS version: 68

LibreDrive Information
Status: Enabled
Drive platform: MT1959
Firmware type: Patched (microcode access re-enabled)
Firmware version: 1.03
DVD all regions: Yes
BD raw data read: Yes
BD raw metadata read: Yes
Unrestricted read speed: Yes

Log:
MakeMKV v1.18.4 win(x64-release) started
Downloading latest SDF to C:\Users\xxx/.MakeMKV ...
Automatic SDF downloading is disabled or failed.
Using LibreDrive mode (v06.3 id=866A98CB9C4E)
Using direct disc access mode
Loaded content hash table, will verify integrity of M2TS files.
File 00010.mpls was added as title #0
File 00009.mpls was added as title #1
File 00008.mpls was added as title #2
File 00007.mpls was added as title #3
File 00006.mpls was added as title #4
File 00005.mpls was added as title #5
File 00004.m2ts was added as title #6
Title #00002.m2ts has length of 7 seconds which is less than minimum title length of 120 seconds and was therefore skipped
Title #00001.m2ts has length of 6 seconds which is less than minimum title length of 120 seconds and was therefore skipped
Title #00003.m2ts has length of 10 seconds which is less than minimum title length of 120 seconds and was therefore skipped
Title #00006.m2ts has length of 10 seconds which is less than minimum title length of 120 seconds and was therefore skipped
Operation successfully completed
Saving 1 titles into directory C:/Video/xxx
1 titles saved

This might help you: MakeMKV drive speed control

In general, I think it is best not to worry about how fast a drive rips a disc. I think it is better to worry about how often the rip is successful. MakeMKV can rip from more than one drive at the same time. If you have a lot of discs to rip get a second or third drive and rip multiple discs at the same time.

I have had this "issue" with nearly every BU40N-type drive I've tested. In fact, these drives usually seem to rip UHD discs at a higher speed than regular Blu-ray discs. Why they're doing that, I have no idea, but I find that it's usually not something to worry about, as dcoke22 said.