mpeg VCD and DivX

[lord loh.]

I just came across a vide format called DivX (.avi extension)

How is this format different in terms of picture quality from mpeg used in VCDs?

 

[Nigel Goodwin]

I just came across a vide format called DivX (.avi extension)

How is this format different in terms of picture quality from mpeg used in VCDs?

As far as I'm aware it's lower quality, but has better compression, to the extent you can have multiple films on a single DVD.

 

[The Mad Professor]

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.

 

[DirtyLude]

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.

https://www.divx.com/

.AVI is a wrapper extension. It can contain any number of video/audio formats inside it, so it's not specific to DivX.

 

[The Mad Professor]

However you slice it , lossy compression sure beats trying to shove a video file into a RAR or ZIP folder in an attempt to save space