www.makemkv.com

For the large majority of disks I process, I get pages of this:

Error 'Scsi error - MEDIUM ERROR:L-EC UNCORRECTABLE ERROR' occurred while reading '/VIDEO_TS/VTS_01_1.VOB' at offset '1867950080'
Error 'Scsi error - MEDIUM ERROR:L-EC UNCORRECTABLE ERROR' occurred while reading '/VIDEO_TS/VTS_01_1.VOB' at offset '1867950080'
Error 'Scsi error - MEDIUM ERROR:L-EC UNCORRECTABLE ERROR' occurred while reading '/VIDEO_TS/VTS_01_1.VOB' at offset '1867950080'
Failed to save title 0 to file G:/Movie/Crime/Inspector Lewis/title_t00.mkv
Error 'Scsi error - MEDIUM ERROR:L-EC UNCORRECTABLE ERROR' occurred while reading '/VIDEO_TS/VTS_01_1.VOB' at offset '913057792'
Error 'OS error - STATUS_DEVICE_DATA_ERROR' occurred while reading '\Device\CdRom0' at offset '913057792'
Error 'OS error - STATUS_DEVICE_DATA_ERROR' occurred while reading '\Device\CdRom0' at offset '913057792'

Is this lack of a decryption key?
Can it really not read the drive, which is the standard DVD+-RW that ships with Dells?
Please don't try to tell me that all those disks are dirty!

By the error messages, you're dealing with a USB-powered drive that is spinning too fast for its power supply. Make sure it is plugged in to a FULLY POWERED USB port (not an unpowered hub), and if it came with a dual-head cable, make sure both are plugged in.

The cable was correctly installed by the factory.

These errors happen on mainstream movies but not on things like PBS documentaries and releases from non-major studios

"Correctly installed by the factory" - is this an internal, SATA-connected drive?

In the case of USB drives that are powered by the USB, when you get to the point where the drive can increase speed (longer titles), the speed takes more power than the USB cable provides. The drive resets when this happens.

If it is a SATA drive with a regular power connection, these type of errors occur when the disk itself is not readable, and the drive tries "too hard" to read it. While the drive is trying to read it, the operating system times out.

In both cases, you see the 'OS error - STATUS_DEVICE_DATA_ERROR' occurred while reading '\Device\CdRom0', but the causes are different.

Yes, it's internal SATA.

The error from which all others spring is:
Error 'Scsi error - ILLEGAL REQUEST:READ OF SCRAMBLED SECTOR WITHOUT AUTHENTICATION' occurred while reading 'DVD+R-DL PLDS DVD+-RW DU-8A5LH 6D1M' at offset '1048576'

Which is clearly a decryption problem. This happens whether or not MKV is running as admin.

Yes, it would seem to be a decryption problem.

Except... The error occurred while trying to read sector 1048576; why did it work for sectors zero through 1048575?