Question about video

Well, Im back. I have put some recorded video on my computer that is only like 15 minutes long and the size of the avi file is 3.94GB! why is it so big? how do I compress it? ive tried before, but on of the files it only took out like 2 or 3 MB...

That sounds about right for DV AVI.

What do you plan on doing with your video?

You can load it into Windows Movie Maker, edit it and save it to a variety of .WMV video files.

You can create DVD's if you have the correct hardware and software.

Keep your original video until you figure out what you are going to do.



Rich

4GB for 15 minutes, and note that it IS already compressed somewhat (Discrete Cosine Transformation).

Standard DV is 13GB/hour (which is what one MiniDV tape or what a Hi-8 tape in Digital8 mode holds). By capturing or transferring to the computer, you are simply copying that data digitally (losslessly) from 15 minutes of tape into a ~4GB file on your computer.

What you do next depends upon what you want. If this video will go to a DVD, then you will encode it (compress it lossily) down to DVD format using an MPEG2 encoder and the size will be about 1GB or so (depending upon the "bitrate" and quality of the lossy compression you want).

If your end goal is to put this 15 minute video clip on the web (or email), then you will use some far more drastic (and lossy, lowering quality) compression to get a small file suitable for emailing or streaming on a web site.

No matter how you look at it, video is a lot of data! The more data you can preserve, the higher quality the final product will be... but of course the most storage space it will consume. HighDef HDV is "stored" in MPEG2 on those 13GB tapes, but when fully decompressed is 108GB/hour!

Note that you have "video data" and can manipulate it as such. Don't try to "ZIP" or "RAR" the file - using a data data compression on it. You won't save much and the result won't be "usable as video". The "intelligence" behind MPEG2, MPEG4, H.264, and other video encoding schemes is that they compress the visual content into a far smaller file size, but do so "losssily" by actually deleting data but delete what the eyes and brain don't concentrate on. For example, movement from one frame to another is preserved, but subtle shading and "colour" in dark areas of the video is not as accurately preserved. Within "movement", more "data space" is dedicated to describing high-contrast and sharp edges as opposed to large areas "walls, not edges" of similar undistinguised areas. If overdone or overzealous on the lossy compression, this can sometimes be seen as "blockiness". The overall goal is to keep as high a quality video (as perceived by viewers) in as small a file size as possible. It IS a tradeoff, and this ability to comprimize starts with DV (Digital8) recording as much video data as it can (13GB/hour) so YOU the end user can choose how to compress it, with what encoder, and with how much degredation/loss you are willing to sacrifice to achieve.

In short, going to a DVD give a pretty good quality video in a convienent media = say an hour onto a 4.7GB DVD blank at a 8000kbps bitrate (down from the original Digital8 from the camcorder at 25000kbps bitrate).