DVD-ROM vs DVD-R

[af2000]

I have been informed in the past that ALL commercially available DVDs were in the DVD-R format. I suspect this is incorrect. Do commercial DVDs represent a different media format: DVD-ROM that is alongside DVD-R and DVD+R? So the DVD-R and DVD+R war was simply for writable discs available to the consumer, not commercially available discs?

Given the capacity is nominally different between DVD-R and DVD+R is one closer to the commercial discs? When writing a disc, If I were to specify the layer break, would there ever be problem regarding the differences in these mediums capacities from DVD-ROM to DVD-R or DVD+R? For example, where a Commerical DVD layer break wouldn't be able to be the same on a DVD-R or DVD+R or is this never a problem?

[Subtitles]

It has been many years ago since I used a DVD. I remember my preference was DVD-R and DVD-RW (which made it possible to rewrite to the disc several time).
I think DVD+R was only write once that is why I didn't like to use them, but I could be wrong.

[jagabo]

Commercial discs are almost alway DVD-ROM. Those are made by mechically pressing the digital dot pattern onto a solid substrate. These are cheapest to manufacture if you are going make thousands of copies.

https://www.youtube.com/watch?v=_fMHvH8WmWs

DVD-R and DVD+R are write once media. The DVD burner "burns" a digital dot pattern into a chemical layer. Once a portion of the disc has been burned that portion cannot be erased and reused.

DVD-RW and DVD+RW are re-writable media. Again the DVD burner burns a digital dot pattern into a chemical layer. But these discs can be erased and used over and over again.

DVD-R and DVD-RW made it to market slightly earlier than DVD+R and DVD+RW. So in the early days the former had better compatibilitiy. After a year or so support for both were common and near universal.

[Cornucopia]

Commercial discs of any major size and/or quality are ALL stamped/pressed type (CD-DA, CD-ROM, DVD-ROM, BD-ROM).
A few fly-by-nights, mom & pop, and VERY budget commercial enterprises (both domestic & international) will distribute via recordable media (CD-R, DVD-R, DVD+R, BD-R). It would only be a very sketchy (and very FOOLHARDY) source that would distribute RW/RE (re-usable, rewriteable) type media.

The choice of +R, +RW vs -R, -RW should be considered on a target machine-dependent compatibility basis.

Scott

[usually_quiet]

Most commercial DVD-ROM discs are dual-layer discs. The preferred burnable equivalent is DVD+R DL.

[af2000]

Thanks for the large number of quick answers. When I'm referring to DVD-R, I also mean DVD-R DL, the same with DVD+R and DVD+R DL.

Is there any consideration regarding the layer break though? I have old notes on the capacities of DVD-R, DVD-R DL, DVD+R, DVD+R DL from a while back, but I cannot find details of the exact capacities of commercial DVDs on Google. If the layer break was at its maximum on a commercial DVD, I wonder if that would always translate correctly if the DVD-R DL or DVD+R DL media capacitiy was less enough to cause problems. Perhaps it is of no concern.

[Bwaak]

If I remember correctly, layer break was an issue in the mid 1990s when RAM was still expensive, and DVD players had no buffers or very small buffers. I think that since the late 1990s it stopped being an issue. I don't know whether the break is encoded in the files, but after you rip a DL DVD, you can then burn it back to a DL disc, and ImageBurn suggests several layer change points, which you can test before burning. I did not have major issues with burning DL discs. Sometimes they would turn coasters, but this is another matter I think, not related to layer change.

As for the difference between +R and -R, there are benefits to bother formats, it is all in wikipedia. All modern players handle both formats.

[hech54]

I could be wrong.

You are.

[usually_quiet]

If I remember correctly, layer break was an issue in the mid 1990s when RAM was still expensive, and DVD players had no buffers or very small buffers. I think that since the late 1990s it stopped being an issue. I don't know whether the break is encoded in the files, but after you rip a DL DVD, you can then burn it back to a DL disc, and ImageBurn suggests several layer change points, which you can test before burning. I did not have major issues with burning DL discs. Sometimes they would turn coasters, but this is another matter I think, not related to layer change.

As for the difference between +R and -R, there are benefits to bother formats, it is all in wikipedia. All modern players handle both formats.

One difference is that DVD-R DL has always been harder to find. DVD+R DL is much easier to find and is reputed to burn more reliably. I have always used Verbatim DVD+R DL when I need more capacity.