--- title: Richard Geldreich's Blog: XUBC7 Low-Level Format Document description: A new codec called XUBC7 v1 is described as the first DCT-based BC7 texture compression codec. It supports lossless or lossy coding of the full BC7 format... canonical: https://daily.dev/posts/richard-geldreich-s-blog-xubc7-low-level-format-document-axycnidki twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Richard Geldreich's Blog: XUBC7 Low-Level Format Document | daily.dev og:description: A new codec called XUBC7 v1 is described as the first DCT-based BC7 texture compression codec. It supports lossless or lossy coding of the full BC7 format... og:url: https://daily.dev/posts/richard-geldreich-s-blog-xubc7-low-level-format-document-axycnidki og:image: https://api.daily.dev/og/posts/AxycNidkI.png og:image:alt: Richard Geldreich's Blog: XUBC7 Low-Level Format Document og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Richard Geldreich's Blog: XUBC7 Low-Level Format Document **[Richard Geldreich's Blog](https://daily.dev/sources/richg42)** · 2 min read · 0 upvotes · 0 comments ## Summary A new codec called XUBC7 v1 is described as the first DCT-based BC7 texture compression codec. It supports lossless or lossy coding of the full BC7 format including all modes, partitions, and options, using absolute or residual DCT with dozens of predictors similar to modern image codecs like WebP. It offers threaded, all-integer deterministic decompression with optional SIMD, making it suitable for WASM. Lossless bitrate runs ~3.5-5.6 bpp and lossy ~1.2-2.5 bpp, compared to plain BC7's 8.0 bpp, with lossless mode rivaling lossy RDO BC7+LZ codecs in efficiency without quality loss. A planned v2 will use adaptive 2x2-4x4 macroblocks to push lossy bitrate below 1.0 bpp. The format is also described as universal, capable of transcoding the BC7 latent directly to ASTC LDR 4x4 blocks, falling back to a real-time analytical encoder (bc7f) for partition patterns that don't map directly. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is XUBC7 and how does its bitrate compare to plain BC7 texture compression? XUBC7 v1 is the first DCT-based BC7 codec, supporting lossless or lossy coding of the entire BC7 format including all modes, mode features, and partition patterns. Its lossless bitrate runs about 3.5-5.6 bpp and lossy mode about 1.2-2.5 bpp, versus plain BC7's fixed 8.0 bpp, with lossless mode matching lossy RDO BC7+LZ codecs without sacrificing quality. _Track new texture compression codecs like XUBC7 as they emerge by following graphics engineering coverage on daily.dev._ ### Can BC7 texture data be transcoded directly to ASTC format? Yes, XUBC7's BC7 latent can be transcoded directly to ASTC LDR 4x4 blocks by converting the BC7 block configuration to ASTC's equivalent, since ASTC is more flexible than BC7. In rare cases where a BC7 partition pattern index has no direct ASTC mapping, the bc7f real-time analytical encoder can be run in a mode that outputs ASTC instead. _Engineers weighing BC7 versus ASTC transcoding paths can follow codec developments like this on daily.dev._ ## Similar posts on daily.dev - [Richard Geldreich's Blog: XBC7](https://daily.dev/posts/richard-geldreich-s-blog-xbc7-baoyp5vfv) · Richard Geldreich's Blog · 0 upvotes · 0 comments - [Richard Geldreich's Blog](https://daily.dev/posts/richard-geldreich-s-blog-y0tvpbsdx) · Richard Geldreich's Blog · 0 upvotes · 0 comments - [Richard Geldreich's Blog: XUBC7](https://daily.dev/posts/richard-geldreich-s-blog-xubc7-vdwectleo) · Richard Geldreich's Blog · 1 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/richard-geldreich-s-blog-xubc7-low-level-format-document-axycnidki) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Richard Geldreich's Blog: XUBC7 Low-Level Format Document","url":"https://daily.dev/posts/richard-geldreich-s-blog-xubc7-low-level-format-document-axycnidki","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/richard-geldreich-s-blog-xubc7-low-level-format-document-axycnidki"},"datePublished":"2026-08-31T21:44:40.698Z","dateModified":"2026-08-31T23:23:22.193Z","description":"A new codec called XUBC7 v1 is described as the first DCT-based BC7 texture compression codec. 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Its lossless bitrate runs about 3.5-5.6 bpp and lossy mode about 1.2-2.5 bpp, versus plain BC7's fixed 8.0 bpp, with lossless mode matching lossy RDO BC7+LZ codecs without sacrificing quality. Track new texture compression codecs like XUBC7 as they emerge by following graphics engineering coverage on daily.dev."}},{"@type":"Question","name":"Can BC7 texture data be transcoded directly to ASTC format?","acceptedAnswer":{"@type":"Answer","text":"Yes, XUBC7's BC7 latent can be transcoded directly to ASTC LDR 4x4 blocks by converting the BC7 block configuration to ASTC's equivalent, since ASTC is more flexible than BC7. In rare cases where a BC7 partition pattern index has no direct ASTC mapping, the bc7f real-time analytical encoder can be run in a mode that outputs ASTC instead. Engineers weighing BC7 versus ASTC transcoding paths can follow codec developments like this on daily.dev."}}]} ```