Editing S3 Texture Compression (section)

== Data preconditioning ==
BCn textures can be further compressed for on-disk storage and distribution ([[texture supercompression]]). An application would decompress this extra layer and send the BCn data to the GPU as usual.

BCn can be combined with Oodle Texture, a lossy preprocessor that modifies the input texture so that the BCn output is more easily compressed by a [[LZ77]] compressor ([[rate-distortion optimization]]). BC7 specifically can also use "bc7prep", a lossless pass to re-encode the texture in a more compressible form (requiring its inverse at decompression).<ref>{{cite web |title=Oodle Texture Compression |url=http://www.radgametools.com/oodletexture.htm |website=www.radgametools.com |access-date=2023-04-03 |archive-date=2023-03-18 |archive-url=https://web.archive.org/web/20230318033018/http://www.radgametools.com/oodletexture.htm |url-status=live }} Open source part mentioned: [https://github.com/richgel999/bc7enc_rdo bc7enc_rdo] {{Webarchive|url=https://web.archive.org/web/20210202215707/https://github.com/richgel999/bc7enc_rdo |date=2021-02-02 }}</ref>

crunch is another tool that performs RDO and optionally further re-encoding.<ref>{{Cite web|url=https://github.com/BinomialLLC/crunch|title=crunch open source texture compression library|website=GitHub|access-date=2016-09-13|archive-date=2016-09-09|archive-url=https://web.archive.org/web/20160909164533/https://github.com/BinomialLLC/crunch|url-status=live}}</ref>

In 2021, Microsoft produced a "BCPack" compression algorithm specifically for BCn-compressed textures. Xbox series X and S have hardware support for decompressing BCPack streams.<ref>{{cite web | url=https://learn.microsoft.com/en-us/gaming/gdk/_content/gc/system/overviews/directstorage/directstorage-overview | title=DirectStorage Overview - Microsoft Game Development Kit | date=16 March 2023 | access-date=3 August 2023 | archive-date=3 August 2023 | archive-url=https://web.archive.org/web/20230803135559/https://learn.microsoft.com/en-us/gaming/gdk/_content/gc/system/overviews/directstorage/directstorage-overview | url-status=live }}</ref>