[M4IF Technotes] Average compression

[Christoph Lampert]

On Fri, 29 Nov 2002, Roland Bengtsson wrote:
> I wonder how much compression MPEG-4 can achieve. Of course this is a very 
> general questions and the compression depends on many things like the 
> movie, tha algorithm that is used etc. But I still want to know: I have 
> seen a number around 17x compression. 

That's a rather low number, I guess. 
For normal material (not too noise, etc.) you get rather good quality with
less than 0.2 bits per encoded pixel, which is compression ratio of 
1:60 over uncompressed YUV 4:2:0 material (12 bits per pixel), and even 
1:120 over uncompressed 24 bit RGB (24 bits per pixel). 
Even DVD-quality MPEG-2 (with up to 10MBps at 720x576 25fps) reaches a
ratio of 1:12 or 1:24. 
Christoph
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