Just want to ask about Compression

[SHENGTON]

Just want to ask about Compression. I got here a video clip which is 98,919MB size. When I compressed it using WinRar it took only 90,717MB. I thought that when I compress it it will reduce to 50% of the size.

Now my question is:
What do you think is problem? The WinRar compressor isn't that effective?

[Eg0Death]

What is the file format of your video? 

[SHENGTON]

The format is MPEG Sir.

[Deerpark]

Movies formats are generally not very compressible with lossless compressors like RAR.
You are never going to see anything near 50% compression on a movie format, you're very lucky if you get 10%.
Why this is isn't easy to explain but basically it is because media files like movies and sound doesn't contain much repeated data. And file compressors work by finding patterns of repeated data in the files.

[Eg0Death]

Yeah, what Deerpark said. 

You might be able to reduce the file size by converting to a different format or quality level though.

[patio]

Video files compress the least while for example a simple text file can compress the most...

The compression ratio is more dependent on the file type rather than the method of compression.

Grab a Coffe and have a read

[SHENGTON]

Thanks Sir patio, Eg0Death and Deerpark!

What do you mean about the "repeated data"?

[Deerpark]

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

[Dias de verano]

all video formats except for RAW video are already compressed, using techniques similar those which file compression programs use. Same applies to jpg images. Windows bitmap (bmp) come in compressed and non compressed varieties.

[SHENGTON]

Thanks sir Deerpark for the link and to you too sir patio!

@Dias de verano
what do you mean about the "RAW video"?

[Dias de verano]

@Dias de verano
what do you mean about the "RAW video"?

It is, as I wrote, an uncompressed video format. The files have the .avi extension and are very large.