Re: help needed - how to optimise compression for Quicktime dance

nate pagel (
Mon, 15 Jun 1998 09:59:29 +0000

To continue where this is left....

Sorenson is an excellent, relatively new codec that slowly compresses Quicktime
3.0+ movies to a very small size. As indicated QT3.0+ is required to view. If
older versions of QT are also the target, then the codec to use is Cinepak,
which does not look as nice as Sorenson but compresses similarly.

Another disadvantage with Sorenson at this point is to compress movies to frame
sizes other than 320x240 pixels you need to actually buy the codec for ~$400.
Other codecs are more or less free.

The other things that influence file size in Quicktime generally are time,
window size, audio rate and frame rate. A shorter movie results in a
proportionately smaller file. Decrease your movie from 640x480 to 320x240 and
get approximately a 1/4 decrease in file size (the latter is 1/4 the area of
the former). Decreasing your audio rate will give you a slight file size
saving. Decrease your frame rate from 15 frames per second to 5 frames per
second and get a 1/3 decrease in file size.

This is a fairly simplistic analysis but should suffice. Following these rules
you can get your file size down to whatever you want it to be. Quality and
acceptability are another matter.

Nate Pagel

Richard Povall wrote:

> >
> >He's trying to find a suitable codec for the Quicktime format that outputs
> >a filesize of
> >around 250-400k, and is m\small enough for reasonable download over the web
> >and/or email
> >
> You don't say how long these movies that you want to be 250K are, but you
> are probably asking the impossible. The best quicktime compression
> currently avilable is the Sorenson codec, which is only available through
> QuickTime 3 (viewers would have to have QT3 or QT3 for Windows installed in
> order to view it). I just converted a full screen movie that was 397MB to
> a quarter screen compressed movie that became 7.1MB. This is a pretty
> remarkable rate of compression, given that the final quality is really
> quite good. However, it's still big for a web document. Such is life -
> the net still ain't very good as a means of distributing video unless you
> have a fast connection.
> R
> R i c h a r d P o v a l l
> Assoc. Prof of Computer Music and New Media / Chair, TIMARA Dept.
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