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Metal Lossy Compression Format

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Ignacio Castaño

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Description

Metal Lossy Compression Format is a technical blog post by Ignacio Castaño on ludicon.com reverse-engineering Apple's undocumented Metal lossy texture compression on A15 and M2 class GPUs. Applications see roughly 2:1 storage reduction transparently when the driver selects lossy modes.

Castaño documents an 8 x 4 block layout, variable-length packed tiles with metadata indexing, and families of R8-oriented modes discovered by aliasing texture and buffer heaps. The write-up is aimed at Metal programmers debugging bandwidth, residency, and format compatibility rather than at end users toggling quality settings.

Advanced Apple platform graphics engineers working with texture formats and hardware compression behavior are the readers. Prior Metal resource heap experience is helpful when reproducing the experiments.

The article is free on Castaño's blog as a single deep dive. Castaño's Metal and texture format posts are frequently linked in cross-platform graphics debugging discussions.