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Date: Fri, 02 Apr 2010 09:45:12 -0400
From: Frank Warmerdam <warmerdam@pobox.com>
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Subject: Re: [Tiff] TIFFReadScanline and large compressed one-strip files
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Folks,

Thanks for the feedback.

I'd like to whack the file producer upside the head, but other than a bit
of moral satisfaction it does not solve the problem at hand.

It is also not really ideal for my client to process the files externally.
They have a popular desktop application that they would like to have
support these files in a reasonably well performing way.

As Joris suggests, it would have been nice if libtiff had been implemented
with a streaming data flow into the decoders but it was not done that way
and I'm not inclined to restructure things to do that properly.

However, I am inclined to sort of fake a sort of streaming for those using
the TIFFReadScanline() interface by keeping only a window of the raw data
in the tif_rawdata buffer for this case.   It looks like I should be able to
this without actually changing the decoders as long as I am careful.

This is likely to be a substantial patch, and not one I am inclined to
incorporate in CVS before 4.0 final is released.  So it will likely live
in bugzilla as a patch for a while.  I'll send notice if I'm successful
with it.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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