Pioneer drive with damaged DVD produces junk data, not error flags

[kaysee]

I tried doing data rescue from a damaged DVD using ddrescue with a Pioneer BDR-TD05AS that is new to me, and was surprised that a rescue of supposedly 100% produced garbled video.

I associate this behavior with LG drives and their "Jamless" playback feature, which handles damaged areas of a disc by not indicating that errors occur, and instead outputs junk data. Do Pioneer drives have a mode that does this as well? I assumed that the "PureRead" mode in Pioneer drives is only for audio CDs.

[thetoad]

you have to authenticate the disc to the drive first with libdvdcss, otherwise it will be scrambled. lsdvd /dev/<optical device> should do that if libdvdcss is installed.

[kaysee]

No, I am copying the encrypted data and forming a disc image, not decrypted, from the DVD. Decryption happens later, after the data rescue step.