Drive Partial failure - Returns bad sectors as good - DVD

[cas206]

I have two LG WH16NS40 Rev 1.02 drives. I have been backing up a pile of DVD's (makemkcon --noscan --decrypt disc:0 out.iso). This has been working for a couple days. However, one drive has been returning a good backup status (Backup done x 2) , but makes a bad backup image. Mounting the image and attempting to play the VOB files, shows good VOB's at the start, but at some point, the VOB becomes corrupted (still encrypted?). Doing the same procedure with the same disk in the other drive gets good VOBS, all the way through. The concerning part is this is a hidden/soft failure mode that only becomes apparent when trying to play back the image. The aggravating part is that I need to go back and test a pile of images to look for bad ones to redo.

Is there a known hardware failure mode that would cause this and has a fix? Or recycle the drive? I don't think a dirty lens would return good sector reads. Could misalignment do this?

[segfaulted]

That sounds like LG's jamless play feature. It sends back junk data instead of reporting a read failure.

There's no proper way to turn it off, other than reflashing a different firmware such as ASUS BW-16D1HT, supposedly.

[cas206]

Sounds Legit. So it could be a dirty lens, misalignment, or any number of issues causing a bad read, but LG just returns the junk with no error.

[Coopervid]

Sounds Legit. So it could be a dirty lens, misalignment, or any number of issues causing a bad read, but LG just returns the junk with no error.

Flash to ASUS w/o jamless play. Do a good clean regarding the disc.

[cas206]

I probably should have also mentioned, I'm working under Linux. I was focused on the hardware side and neglected to mention that. I've read that the DVD library can also ignore errors. So it might not have been a jamless feature.

Regardless, I do have a bad drive. I have a disk that consistently completes a makemkvcon backup in the bad drive that leads to a image that has partially corrupted video. It consistently works correctly in the other drive.

I'm now working in Windows (no potential linux dvd library issue) with the ASUS firmware flashed to the good drive (no potential jamless issue). Time to redo all my copies.

[ryley]

I probably should have also mentioned, I'm working under Linux. I was focused on the hardware side and neglected to mention that. I've read that the DVD library can also ignore errors. So it might not have been a jamless feature.

Regardless, I do have a bad drive. I have a disk that consistently completes a makemkvcon backup in the bad drive that leads to a image that has partially corrupted video. It consistently works correctly in the other drive.

I'm now working in Windows (no potential linux dvd library issue) with the ASUS firmware flashed to the good drive (no potential jamless issue). Time to redo all my copies.

It really does sound like you were encountering the jamless play “feature”. It is good that the Asus firmware is an option for 5.25” drives but I don’t believe there is a comparable firmware option for slim/portable drives.

I might be wrong but my recollection is that MakeMKV doesn’t utilise any external libraries for reading DVDs or Blu-rays. This should be the same on all three supported platforms. The MakeMKV Linux builds are linked against a few libraries such as libavcodec for codec/format compatibility but not libdvdcss or libaacs.

I personally have experienced my BH16NS55 and WH16NS60 drives returning garbage data in rare occasions on both Windows and Linux.

[cas206]

I probably should have also mentioned, I'm working under Linux. I was focused on the hardware side and neglected to mention that. I've read that the DVD library can also ignore errors.

I might be wrong but my recollection is that MakeMKV doesn’t utilise any external libraries for reading DVDs or Blu-rays. This should be the same on all three supported platforms. The MakeMKV Linux builds are linked against a few libraries such as libavcodec for codec/format compatibility but not libdvdcss or libaacs.

I personally have experienced my BH16NS55 and WH16NS60 drives returning garbage data in rare occasions on both Windows and Linux.

First, thanks for the +1 to my observation. Helps reduce the impression that I might be misinterpreting my observations.

Second, you are probably correct in your recollection. In the middle of trying to figure out why some of my images were showing up with corrupted video, I also ran into a disk that makemkvcon couldn't backup. Took me awhile to figure out I had two separate issues, that it was the structure on this particular disk causing a problem (with a work around of switching to CellTrim instead of CellWalk). I was using various other tools (dvdbackup, ddrescue, ffmpeg) while working my way through this. "dvdbackup", in particular, posted messages from libdvdread to the screen. At some point, I mistakenly started associating those messages with "makemkvcon" as well. A simple test just revealed I was mistaken.