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From: walker@chang.unx.sas.com (Doug Walker)
Subject: Re: How big is that D1/MPEG/RGB/GIF file really?
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Date: Mon, 1 May 1995 19:55:53 GMT
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In article <3o3al3$t9@ixnews4.ix.netcom.com>, mitch4@ix.netcom.com (Mitch Goldstrom) writes:
|> I need to write a quick and dirty program which will let the lo^H^Huser
|> select a video/audio/image format (D1, MPEG, RGB, Gif, Sun Raster, mv,
|> qt, aiff aifc, wav, au, etc...) then enter the duration in seconds or
|> frames, and spit out the amount of disk space that the file will take
|> up.
|> 
|> Can anyone recommend a book or ftp source or anything that would
|> explain what D1 means and how to compute the size of a frame.  The same
|> for MPEG, etc.....

With MPEG, it will depend on the image quality and compression method you want
to use.  At a resolution of 352x240 and a frame rate of 30 fps, you can get 
recognizable video at 100,000 bytes per second, pretty good results at 150,000 bps 
(single-speed CD-ROM drive level), very good results at 200,000 bps, and excellent
results at 250,000 bps.  (This includes bandwidth for audio.)  Levels above 250kbps 
don't seem to improve the video much.

Most MPEG video you see on the WWW is actually QSIF size (160x120) and it is all
I-frame (no motion vectors) and no audio.  It also usually runs about 15 frames 
per second of real time.  For at least one sample that I've got, this turns out 
to be about 74000 bytes per second.

-- 
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Any opinions expressed are mine, not those of SAS Institute, Inc.

