What DVD-ROM drives can read?

I am making an application that displays info from optical drives, like model name, vendor name, serial number, region code, reading and writing disk types supported and more. As I didn’t find any technical documentation that could help me, I want to ask these:

  1. can a simple DVD-ROM drive read DVD-R Dual Layer disks?

  2. can a simple DVD-ROM drive read DVD+RW Dual Layer disks?

by saying “Simple DVD-ROM drive” I mean a drive with no DVD writing capabilities.

Some DVD-ROM drives support user-written discs (-R, +R, -RW, +RW, etc). Some do not.

Sometimes it’s a hardware thing [or it is applicable to all drives of a given make & model; regardless of firmware, you cannot enable playback of such discs], sometimes it’s a firmware thing. I think in each case, though, the drive should be able to tell you what it can and cannot do, by responding to a particular query (I wouldn’t know which multimedia command that would be). That information is frequently accurate.

I know I have an old Pioneer DVD-ROM drive from 1999/2000 that seems to audibly struggle trying to read back -R/+R/etc, and it reads at a nonstandard speed, and may even fail at reading without warning.

[QUOTE=Albert;2714237]Some DVD-ROM drives support user-written discs (-R, +R, -RW, +RW, etc). Some do not.

Sometimes it’s a hardware thing [or it is applicable to all drives of a given make & model; regardless of firmware, you cannot enable playback of such discs], sometimes it’s a firmware thing. I think in each case, though, the drive should be able to tell you what it can and cannot do, by responding to a particular query (I wouldn’t know which multimedia command that would be). That information is frequently accurate.

I know I have an old Pioneer DVD-ROM drive from 1999/2000 that seems to audibly struggle trying to read back -R/+R/etc, and it reads at a nonstandard speed, and may even fail at reading without warning.[/QUOTE]
The point is this: I know commands to get some reading and writing features. I know the query command to get WRITING DVD-R DL but I cannot get READING DVD-R DL. So I am wondering, by getting the writing attibute and a drive cannot write this type of disk, can I say for sure that the drive cannot read it too? Are there drives that can read DVD-R DL but they cannot write them? I do not want to tell me how to get this attribute, just tell me if exists any drive that can read DVD-R DL but it cannot write it. I have the same problem with DVD+RW DL disks.

I’m sure some early DVDRW drives did not support writing to DL, but were able to read it just fine. Same for some DVD-ROM drives.

-R media may not work in old DVD-ROM drives due to the booktype of the media. +R media with the booktype set to DVD-ROM [I]should[/I] work in any drive unless the maker has done something screwy or intentionally made the drive refuse to read recordable media.

Thanks a lot for your replays!

Standards are there because there are always exceptions!

[B]Never forget that!!![/B]