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41 lines
2.3 KiB
Markdown
# Supported File Formats #
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crnlib supports two compressed texture file formats. The first
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format (clustered [.DDS](http://en.wikipedia.org/wiki/DirectDraw_Surface)) is simple to integrate into an existing project
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(no code changes are typically required), but it doesn't offer the
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highest quality/compression ratio that crnlib is capable of. Integrating
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the second, higher quality custom format (.CRN) requires a few
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typically straightforward engine modifications to integrate the
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.CRN->DXTn transcoder header file library into your tools/engine.
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## .DDS ##
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crnlib can compress textures to standard DX9-style [.DDS](http://en.wikipedia.org/wiki/DirectDraw_Surface) files using
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clustered DXTn compression, which is a subset of the approach used to
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create .CRN files. (For completeness, crnlib also supports vanilla, block by block DXTn compression too, but that's not very interesting.)
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Clustered DXTn compressed .DDS files are much more compressible than
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files created by other libraries/tools. Apart from increased
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compressibility, the .DDS files generated by this process are completely
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standard so they should be fairly easy to add to a project with little
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to no code changes.
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To actually benefit from clustered DXTn .DDS files, your engine needs to
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further losslessly compress the .DDS data generated by crnlib using a
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lossless codec such as zlib, lzo, LZMA, LZHAM, etc. Most likely, your
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engine does this already. (If not, you definitely should because DXTn
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compressed textures generally contain a large amount of highly redundant
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data.)
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Clustered .DDS files are intended to be the simplest/fastest way to
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integrate crnlib's tech into a project.
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## .CRN ##
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The second, better, option is to compress your textures to .CRN files
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using crnlib. To read the resulting .CRN data, you must add the .CRN
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transcoder library (located in the included single file, stand-alone
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header file library inc/crn\_decomp.h) into your application. .CRN files
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provide noticeably higher quality at the same effective bitrate compared
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to clustered DXTn compressed .DDS files. Also, .CRN files don't require
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further lossless compression because they're already highly compressed.
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.CRN files are a bit more difficult/risky to integrate into a project, but
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the resulting compression ratio and quality is superior vs. clustered .DDS files. |