Title: DVD player/recorder does not even try reading CD-RWs.
There is something I really wonder about.
Disclaimer: I am not quite sure, whether I the DVD recorder or DVD writer's forum is the correct place for this thread, but I guess, that the latter one fits better, because I am talking more about hardware.
I have an old JVC RC-Ex30 CD player that reads CD-RW after cleaning the lens. (It works like that: increase lens laser strength regardless of disc type, until ping comes back. Grundig CD players memorize disc type.)
It is able to detect CD-RWs, but does not even try reading DVD-RWs because of low reflection. Of couse, it can not read DVDs, but it shows response when reading DVD-R and DVD-normal. Reading error, but not “no disc”.
Our DVD recorder DV-Rw250 does not read written CD_RW.
It can not record on blank CDs, only DVDs. But if I read a blank CD-R/RW with it, then it shows just “blank disc”, no reading error. But it can not do anything with it.
YES, the DV-RW250 CAN read blank CD-RWs 50% of all times. That's because blank CD-RW's have 5% more reflection than written ones.
But if I try reading a written CD-RW, then it says “No Disc”. The laser did not try strong enough to detect the disc. This NEVER happened to DVD-RW, even if the CD-RW has a higher reflection degree.
The laser is a DVD writing laser, so it is easily sufficiently strong for reading CD-RW. But the software did not program it to try any harder. If the lens just tried to apply 5% more power when detecting a disc, it would read CD-RW without any problems.
Disc drives are generally restricted to the system.
Here's why: http://www.isoBuster.com/tips/quick_erased_optical_discs_what_is_recoverable_and_how/
Additionally, a computer only sees the user data: http://www.quora.com/How-can-I-make-a-disc-image-containing-full-7203-byte-sectors-nor...tes-per-sector
Some professional disc drives should have a forensic mode, where the computer can directly control the lens and bypasses the software of the disc drive. Of course, the computer should not be able to bypass the physical hardware limitations of the disc drive, which could damage the disc (too high rotation speed) or the drive itself…. But a forensic mode with API could make the computer controlling laser strength, buffer underrun control, rotation speed and negative rotation, laser position, subcode reading, error correction reading, full metadata access, etc..
Disc drive restrictions place it somewhere between mass storage and MTP. But a solid state drive is not much different: the computer does not directly access the file system. It just thinks it does. And there is also SSD-TRiM, which makes accidental deletions critical.
But the SSD itself controls the file system fragmentation to spread writing cycles on many sectors evenly, so that the operating system does not dig holes into specific sectors. A computer virus could also abuse too high control. But there are no virusses in a secured environment such as Hiren's Boot CD (Linux PartedMagic and MiniXP). In that case, full drive control would be highly appreciated.
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