Why is AVI video so large?

brain.nz · Post by **brain.nz** » Sun Aug 06, 2006 10:56 am

Hey everyone, I was just wondering why is AVI video so large in file size compared to Quicktime and MPEG?

Cheers,
brain.nz

slimdog55 · Post by **slimdog55** » Mon Aug 07, 2006 3:36 am

Usually AVI is uncompressed and much higher quality than the compressed MPEG and Quicktime formats.

brain.nz · Post by **brain.nz** » Mon Aug 07, 2006 7:25 am

why does the file of the video increase if you convert from MPEG to AVI? How does the video become higher quality from MPEG?

DEDFX · Post by **DEDFX** » Mon Aug 07, 2006 7:41 am

You mean the size of the file? Because it's becoming an AVI now. The program recognizes it as a video file, not MPG so you can compress that to smaller size or leave it the way it is (AVI) even though its MPEG.

Ornsack · Post by **Ornsack** » Mon Aug 07, 2006 11:16 am

AVI can be whatever size you want it to be. Most AVI codecs use high compression for editing and what not.

MPEG was designed to be smaller in size. I wouldn't use it for editing.

Quicktime is much like AVI, you can use any codec or compress to any file size. There's probably a myth that it's smaller in size because they released compressed trailers all the time in Quicktime.

An AVI DV file is the same size as a Quicktime DV file, for example.

Jperson · Post by **Jperson** » Tue Aug 08, 2006 8:59 pm

Stupid question: What does AVI and DV stand for? I know what they are but don't know what they stand for, I think DV is digital video (am I right?) and the V in AVI is possibly also video, can anyone fill me in here?

Jimbobsquarepants · Post by **Jimbobsquarepants** » Tue Aug 08, 2006 9:01 pm

avi is audio video..............integrated....or something not sure on the I but it is audio video something

film fanatic · Post by **film fanatic** » Tue Aug 08, 2006 9:16 pm

Audio / Video Interleaved, and MPEG is Moving Pictures Expert Group.

UFProductions · Post by **UFProductions** » Wed Aug 09, 2006 12:49 am

I thought it was Audio / Video Interlaced, but shmeh... I guess I was wrong.

Ornsack · Post by **Ornsack** » Wed Aug 09, 2006 1:20 am

Nah, only recently with the advent of DV (Digital Video, by the way!) that footage has been able to be interlaced properly.

brain.nz · Post by **brain.nz** » Wed Aug 09, 2006 1:01 pm

AVI stands for Audio Video Interleaved.

rhys · Post by **rhys** » Wed Aug 09, 2006 1:52 pm

Coool. Does anyone know what jpeg stands for?

Adam · Post by **Adam** » Wed Aug 09, 2006 7:21 pm

Similar to MPEG

JPEG = Joint Photographic Experts Group

http://en.wikipedia.org/wiki/Jpeg

Post by **Matt** » Wed Aug 09, 2006 9:15 pm

Remember that AVI is a container format. The codec defines how the frames are compressed. When you deal with an AVI you need to know what the codec is. AVI on it's own is not enough info. AVI is like a filing cabinet containing pieces of paper that represent frames. The codec is equivelent to what language is written on the paper. It could be French, German or numbers etc.

Therefore AVI isn't 'big' or 'small' because it all depends on the codec.

The size of a file does not determine the quality. When you convert a 50Mb MP3 to CD is takes up ten times as much space because that is what the format demands ... but the quality can *never* go up. Just because something is on DVD doesn't mean it is better quailty than a clip filmed on a mobile phone. There is a difference between what *potential* a format has for delivering quality and what it *actually* delivers for a given clip.

Raptor · Post by **Raptor** » Wed Aug 16, 2006 5:52 am

Right on on the 'container concept Matt, the big difference between AVI and MPEg is how the frames are encoded, the frames in an AVI are compressed based on the selected codec, but each frame contains all the information needed to display that frame. In Mpeg, a GOP is used ( group of pictures) commonly 15 frames. the first frame in the GOP contains the full frame info, the successive frames in the gop contain only the information in each frame that has changed from teh first frame. One of the reasons why MPEG is not a preferred editing format. It still works well, since broadcast satelites use MPEG encoding and that is edited all the time. MPEG files get bigger when converted to AVI since all the frame info is reinserted in each frame during the conversion.