The format "DivX" is often used by to compress a 3 or 4 giga byte ISO file from a DVD down to around 700MB , this is a popular method employed widely by those into file sharing.
To achieve this level of compression something has to be sacrificed and it employs a rather neat trick to do so. Take any two frames of video in sequence and often very little difference can be seen , just like frames of a stop motion animation , in essence much of the data is repeated. Huge savings are made by using the same block of compressed data many times , only objects on the screen that move need to be refreshed.
Take any two frames of video in sequence and often very little difference can be seen , just like frames of a stop motion animation , in essence much of the data is repeated. Huge savings are made by using the same block of compressed data many times , only objects on the screen that move need to be refreshed.
That's the simplest form of compression and it's used in every video compression method. It's nothing new to DivX.
Like Nigel said, it usually sacrifices image quality, but DivX, like most video compression allows you to specify levels of compression, similar to when you save jpeg image, but with the video you have many more options.