Hi, Looks like you are calling cmsDoTransform() with the number of bytes instead of the number of pixels.
Regards Marti On May 5, 2016 11:14 AM, Andreas Frisch <fraxi...@opendreambox.org> wrote: > > Hi guys, > > i wrote a gstreamer wrapper element for littlecms ( https:// > bugzilla.gnome.org/attachment.cgi?id=327238 ) > > I've observed that the functions cmsDoTransformStride and cmsDoTransform > overwrite the subsequent data in my buffer plane if input and output pointers > are pointing to the same position in memory (in-place transformation). > > i wrote a simple test case which shows this issue. > $ gcc -Wall -g `pkg-config lcms2 --cflags --libs` lcms-memory-corruption- > testcase.c -o lcms-memory-corruption-testcase > $ ./lcms-memory-corruption-testcase CP955_F.icc > initalize 3 rows with 4 bpp = 12 bytes of source data... > initalized source data looks like: > row 0@0x1f63a20 0xF0E0D0FF > row 1@0x1f63a24 0xF1E1D1FF > row 2@0x1f63a28 0xF2E2D2FF > > doing transformation data->new_data... > row 0@0x1f63a20 0xF0E0D0FF (subsequent data 0xF1E1D1FF) => 0xF2E3D1FE > row 1@0x1f63a24 0xF1E1D1FF (subsequent data 0xF2E2D2FF) => 0xFED7CEFE > row 2@0x1f63a28 0xF2E2D2FF => 0xB7EDCEF7 > > doing IN PLACE transformation... > row 0@0x1f63a20 0xF0E0D0FF (subsequent data 0xF1E1D1FF) => 0xF2E3D1FE > row 1@0x1f63a24 0xB6ECCEF7 (subsequent data 0xFED8D2FF) => 0xC3E3D1FD > row 2@0x1f63a28 0xFDD4D2FD => 0xEBE0D0F7 > > so first a buffer is filled with data and then a test transformation is > performed into a newly allocated buffer. the result is as expect. > > then another transform is done with output buffer = input buffer, and then > the > subsequent input data is changed by the the cmsDoTransform call even though > the given size is correctly specified with 4 bpp. therefore, the result is > incorrect, except for the very first transformation. it happens with 3 bpp > aswell. > > this in-place transformation is optional in gstreamer and just saves a > memcpy, > so the simplest workaround is operating my gstreamer element in a way where > input and output buffers are different memory, but I'd like to find out why > the > in-place transformation corrupts the input. > the tutorial says on page 15 that it is okay to use the same memory block for > input and output as long as the formats are the same. i haven't debugged yet, > before i investigate more, i'd like to find out if maybe i'm just doing it > wrong? > > cheers > fraxinas > > ------------------------------------------------------------------------------ > > Find and fix application performance issues faster with Applications Manager > Applications Manager provides deep performance insights into multiple tiers > of > your business applications. It resolves application problems quickly and > reduces your MTTR. Get your free trial! > https://ad.doubleclick.net/ddm/clk/302982198;130105516;z > _______________________________________________ > Lcms-user mailing list > Lcms-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/lcms-user ------------------------------------------------------------------------------ Find and fix application performance issues faster with Applications Manager Applications Manager provides deep performance insights into multiple tiers of your business applications. It resolves application problems quickly and reduces your MTTR. Get your free trial! https://ad.doubleclick.net/ddm/clk/302982198;130105516;z _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
