DVD Compatibility
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Types of DVD
Pressed DVDs
Pressed DVDs come in various shapes and sizes (well, not really, but anyway):
- Single Layer / Double Layer
- To tell the difference, look at the inner ring. If it is double layer, it will have two bar-codes.
- All DVD players can read both types. (well, all players you are ever likely to come across...)
- Single Sided / Double Sided
- Yes, you have to flip these over to play the other side.
- Often used for supporting two different Aspect Ratios (e.g. 4:3 and 16:9)
Pressed DVDs are compatible with any reader out there. We like them. ;-)
OTOH, Pressed DVDs can be encrypted with CSS encryption. See Ripping DVDs with Mencoder for more. This happens at the pressing facility, as you need to buy an expensive license for the technology. Generally DVD images are submitted to the pressing facility on DLT tape for mastering.
Burned DVDs
To make life extra fun, there are lots of different ways of writing DVDs. Mostly pretty incompatible...
DVD-R for Authoring
Thankfully this has died, but it used to exist for producing masters for pressing. The writers cost several large fortunes (the same goes for the blank media), but they were as compatible as pressed discs, except for certain reflectivity issues (can someone provide more info on these issues? might be interesting).
DVD-RAM
This was the first rewritable DVD technology. It is totally different to all the other DVD technologies, and most readers and writers can't use it.
It has a truly Random access structure and good error correction. They can handle an order of magnitude (or two) more re-writes than DVD+-RWs. It is also generally in a caddy of some type, adding to the life.
Expected life >30 years.
- If you want to make backups (and have a compatible drive) use this format.
DVD-R (General)
Your average home-grade DVD toasting device writes this disc. It is the most widely compatible available consumer-recordable disc. Most standalone DVD players will play this format, although reflectivity issues take their toll.
- If you want to write DVD Video, use this format.
- If you want to make backups and don't have DVD-RAM, use this format.
DVD-RW
DVD-RW is based on DVD-R, and thus most drives that read DVD-R will read DVD-RW. Not all though, as it has a lower reflectivity.
- If you want to give MP3s to a friend and they swear that their drive can read -RWs, then you might want to use this.
- For personal stuff, use this format.
DVD+R
DVD+R is not an official DVD Forum format and therefore is not permitted to carry the official DVD logo. Similar to the DVD-R format. Slightly less compatible (depending on who you talk to).
DVD+RW
DVD+R is based on DVD+RW. They are both pretty analogous to their - counterparts, except for drive incompatibilities. They were developed before DVD-R and are considered to be a superior format (although this depends on who you ask :-)
Anycase a *VERY* good read is DVD+RW/+R/-R/-RWfor Linux]
- Quote
- As already mentioned, DVD+ groove has "addressing information modulated into it," ADIP (ADress In Pre-groove). This gives you an advantage of writing DVD+RW in truly arbitrary order, even to virgin surface and practically instantly (after ~40 seconds long initial format procedure). In addition, DVD+RW can be conveniently written to with 2KB granularity. DVD-RW in turn can only be overwritten in arbitrary order. Meaning that it either has to be completely formatted first (it takes an hour to format 1x media), or initially written to in a sequential manner. And it should also be noted that block overwrite is never an option if DVD-RW media was recorded in [compatible] Disc-at-once or even Incremental mode, only whole disc blanking is.
DVD+R DL
Home-writable Dual layer discs!
These discs can be read in (mostly the same drives) as DVD+R discs.
- If you want to write LOTS of stuff, use this format.
So, what can my drive use?
Standards
- If it has the "super multi" logo on it, it should read & record everything you can throw at it (bar the odd physical disc incompatibility)
- This is the one you want to buy when you go shopping!
- If it has the "DVD multi" logo on it, it can read & record DVD-R, DVD-RW, and DVD-RAM (i.e. not the + formats)
- If it has the "RW" logo on it, it can read & record DVD+R and DVD+RW formats (i.e. not the - formats)
- If it has the "compact disc" logo on it, it should handle CDs too (although all DVD drives should)
These days, most new drives can read most discs (90% of the time, and excepting DVD-RAM which almost nothing can read).
Reflectivity
Then you have the problem of physically reading the discs. Different makes of disc (and batches) have different reflectivity, and not all drives can read all discs.
Firmware
Firmware versions of both reading and writing drives come into this too, firmware tells the drive how to deal with contemporary media. Sometimes you will find that updating will help with a new brand of disc, sometimes it will make your old discs unusable... :-)
DVD Anecdotes
The most incompatible reader I have ever found was a Sony Hi-Fi standalone DVD recorder (the most widely used DVD player in the target market I was producing DVDs for).
We found that for every batch of blank discs we bought we had to find a new burning strategy. By strategy, I mean:
- what spindle of blanks we used for the master (Verbatim DVD-Rs came out tops most of the time for this)
- what drive (and firmware) to master on
- what firmware to use in the duplicating drives.
It was totally unpredictable what would work...
I think the DVD Forum has a lot to answer for :-)
