[gdal-dev] bit length overflow in deflate compress

[Even Rouault]

Le jeudi 29 décembre 2011 20:15:32, Ivan Lucena a écrit :
> Hi there,
> 
> I am getting a lot of messages like that when using deflate compression
> (zlib):
> 
> $ gdal_translate input.tif output.tif -co compress=deflate
> Input file size is 800, 600
> 0...10...20...30...40...50...60...70...80...90...100 - done.
> 
> bit length overflow
> code 4 bits 5->6
> 
> bit length overflow
> code 16 bits 6->7
> 
> bit length overflow
> code 11 bits 6->7
> 
> bit length overflow
> code 5 bits 6->7
> code 11 bits 6->7
> 
> bit length overflow
> code 3 bits 6->7
> 
> bit length overflow
> code 5 bits 5->6
> 
> bit length overflow
> code 5 bits 6->7
> code 12 bits 6->7
> 
> bit length overflow
> code 11 bits 6->7
> 
> bit length overflow
> code 12 bits 6->7
> 
> bit length overflow
> code 16 bits 6->7
> 
> The input and output image has the same checksum at the end, so what is
> going on?

Ivan, I suppose you are using GDAL internal zlib. This error message comes 
from frmts/zlib/trees.c, and it appears it is only a debug message that is 
output if DEBUG is #define 'd (see zutil.h). On a non-debug build, the message 
shouldn't appear.

> 
> The image is RGB, GDAL is compiled for 32bits running in a win64 machine.
> 
> Regards,
> 
> Ivan
> 
> 
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