Re: [Openexr-devel] DWAA minimum tile size?

[Karl Rasche]

Hey Larry -

What is the single channel named? 

For tiled files, dwaa == dwab, so you should hit the same issue with either case. There’s a couple of paths that lead to hitting zlib, and the channel naming should tell us which that is. 

My guess is there’s some degenerate case in the buffer sizing logic.

Karl

On Tue, Nov 20, 2018 at 9:49 PM Larry Gritz <address@hidden> wrote:

Here is a strange behavior (easy to repro for those of you who might have a copy of OIIO lying around):

    # works
    oiiotool --pattern checker 512x512 1 -d half -compression dwaa -tile 16 16 -o test.exr

    # fails
    oiiotool --pattern checker 512x512 1 -d half -compression dwaa -tile 8 8 -o test.exr

Just writing a simple tiled 1-channel half exr file with dwaa (or dwab) compression. It succeeds with 16x16 tiles but fails with 8x8, wherein writeTiles() throws an exception with the following message:

    > Failed to write pixel data to image file "test.bb700d14.temp.exr". Data compression (zlib) failed.


Curiously, if I instead make a 3-channel file,

    oiiotool --pattern checker 512x512 3 -d half -compression dwaa -tile 8 8 -o test.exr

that succeeds (also fine with 4x4, 2x2, 1x1 tile size). Using zip compression is fine. I can only make it fail with the specific combination of 1 channel images + dwaa/dwab compression + tile size < 16.

Anybody have any insight, or has this bug been reported before?

Here's the OIIO issue if anyone wants to follow up there or reference it:
https://github.com/OpenImageIO/oiio/issues/1844

--
Larry Gritz
address@hidden





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