Wikipedia says:

MPEG4-MVC compresses both left and right eye views with a typical 50% overhead compared to equivalent 2D content, and can provide full 1080p resolution backward compatibility with current 2D Blu-ray Disc players.

So if a Blu-Ray 3D is completely backwards compatible to a regular Blu-Ray, why do all consumer Blu-Ray-3D packages contain a 2D as well as a 3D disc? Is that just marketing (so people will even buy it if they don’t yet have a 3D-capable setup) or is there some technical reason behind this?

  • Disk allocation and production is part of A/V production, so I think this is safely on topic, particularly since there is a real production reason why this is.
    – AJ Henderson
    Dec 3, 2013 at 21:43

3 Answers 3


Disk space. The 3d content takes more space so there is generally not enough room for special features. The 2d special features are only on the 2d disk. They take up the room that the second eye takes on the 3d disk. They could make a special features only disk, but this is generally more expensive since it requires another master and another production line. It's more cost effective and better marketing to just include the 2D copy.

  • Why does making a special-features-only disc require a new master while a 2D disc does not? Doesn’t every version with different content require a new master? Dec 4, 2013 at 7:30
  • 1
    @RaphaelSchweikert - yes, but most often the 2D disc is the same as the non-3d retail version, so they would make that disk anyway. They don't just sell all 3d versions because it doesn't make sense to include the 3D disk when someone doesn't want it (extra cost) and because the convention is to charge extra for the 3d version. If they ever stop charging extra, we may see them just release the 3d version and not bother with a 2d, but currently that isn't the market direction.
    – AJ Henderson
    Dec 4, 2013 at 14:09

One aspect that I hadn’t considered when posting the question: For this to work, the 2D version would have to be somehow be “contained” in the 3D version. I wasn’t considering that this might not be true at all.

What 3D-MVC being backwards-compatible to 2D-AVC actually means is that a non-3D-capable decoder will “see” either the left or right eye track of the 3D version.

It’s possible that a proper 2D version doesn’t match either of those.

That is especially true for movies not initially produced in 3D and not captured with stereo cameras. 3D conversion is often easier to do by slightly modifying the perspective of the 2D version for both the left and the right eye. The end result being that neither side exactly matches the original 2D version.


My guess is that because you spent a lot of money for the 3d equipment, they know you ARE going to buy 3d products no matter what the cost. The companies include the 2d versions to lessen the pain of the cost giving you the illusion they are not screwing you. It is about how much money goes into their pockets, not about how much content goes in the packaging.

  • Except that doesn't hold up. Lots of people buy 2d stuff even for their 3d player and either way, if they "knew we would buy 3d" then they don't need to include a 2d disk. The fact is that there isn't space for content on the 3d disk (because of the extra size) that can fit on the 2d disk and it isn't economical to make a special disk for special features when it is already on a 2d disk. Mastering is the expensive part of a production disk run. The disks themselves are simply stamped from the master. Fewer production lines = better bottom line.
    – AJ Henderson
    Sep 19, 2014 at 19:27

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