[Gdal-dev] ecw-compressing >500MB files

[Frank Warmerdam]

On 5/12/05, Ken Boss <Ken.Boss at dnr.state.mn.us> wrote:
> Under FWTools 0.9.8, I can successfully use gdal_translate to generate
> an ECW output from a 400 MB input file.  If I try to do the same with a
> 750 MB input, however, I get:
> 
> gdal_translate -of ECW -co target=95 two_tiles.tif two_tiles.ecw
> Input file size is 18988, 14016
> 0.100 - done.
> ERROR 4: `d:\ken_mrsid\test_tiles\two_tiles.ecw' does not exist in the
> file syst
> em,
> and is not recognised as a supported dataset name.
> 
> I'm guessing this might owe to input file size limitations, but looking
> at the ECW 3.1 SDK page at http://www.ermapper.com/ecw/ and the price
> list at http://www.ermapper.com/document/doc.aspx?doc_id=54, I'm left
> with the distinct impression that the free GPL-style license for the SDK
> (surely this is what gdal uses?) provides unlimited compression.

Ken,

I believe that the file size limitation is what you are running into. 
I believe the FWTools 0.9.8 supports large files, but you need to
"tell" the software you have the legitimate right to compress large
files. This is accomplishing by setting the ECW_LARGE_OK 
creation option to YES. 
eg. 

gdal_translate -of ECW -co ECW_LARGE_OK=YES big.tif big.ecw

Note that by setting this flag, it is my intent that you are acknowledging
that you have conformed with any requirements of the ECW license.

Best regards,
-- 
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