[Ffmpeg-devel] New Video Codec for low grunt embedded CPU's

Peter Cech cech
Thu Mar 23 00:38:01 CET 2006

On Wed, Mar 22, 2006 at 10:20:01PM +1100, Steven Johnson wrote:
> Peter Cech wrote:
> >Did you take a look at GIF and MNG?
> >  
> >
> GIF is only 8Bpp, i need to also do at least 15Bpp as well,  Plus its
> just not very good.
> And i've yet to see a single commercial application that supports MNG, I
> (or more correctly my users) need to be able to generate animations
> using off the shelf tools.

Yes, mng support is scarce. On the other hand, encapsulating libmng into
plugin or windows codec API would not be more work than creting new

> Plus, doesnt MNG use ZLib as its primary
> compression technique, like PNG does?


> >If zlib is too slow for your application (decoding, right?),
> >
> Yes, decoding needs to be quick.  Zlib is too slow.
> > try
> >Z_HUFFMAN_ONLY, Z_RLE or Z_FIXED strategies when compressing, it should
> >speed up decompression as well (no ide how much).
> >  
> >
> Im not sure what you meant by this???

Libz offers several parameters to tune. Typically one calls deflateInit
that accepts compression level as an argument and sets all the other
parameters accordingly. But if you use defalteInit2 function instead,
you can set all parameters individualy. One of them is compression
strategy. Documentation is directly in zlib.h.

Probably the easiest way to try it is to recompress some png images with
OptiPNG (http://www.cs.toronto.edu/~cosmin/pngtech/optipng/). Use switch
-zs2 for Z_HUFFMAN_ONLY and -zs3 for Z_RLE (there is no support for

Peter Cech

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