DVD Length - How does it fit?

[Lakeslad]

If DVD's can only hold 120 minutes of data, how do movies that are longer than two hours fit on a DVD?

[karlpeg]

I think its something to do with the dual layer processing.
Thats why when you watch a DVD it pauses for half a second at somepoint in the movie.

[fo3nix]

The above is correct. Most are dual layer -- just like sandwiching two discs together.

[Mattk]

or maybe the movies are coded as data ie 4.7gb or less ?

surely if it states 120 min video that is its maximum ? if it could offer more then they would surely state that on the packaging ?!

[rojash]

There is no precise time length for the capacity of a DVD. It will depend entirely on the type of content and the amount of compression applied.

[Loosehead]

As rojash says the limit of a DVD is expressed in space not time. The amount of space taken depends on compression factor etc. ie each frame of film will be stored compressed and the amount of compression depends on the detail in the frame so for example if there us a shot of a blank sky then that will compress down to almost nothing but if there is a shot with a lot of people and detail then the compression algorithm will have much less to compress. If time is quoted it is only a guide not and absolute limit.