The near-final macOS High Sierra golden master has been seeded to devs

The golden master (GM) candidate of macOS High Sierra was released to developers today. The GM doesn't add any significant new features over the previous beta version, but it can be helpful for QAing Mac software updates for High Sierra before the public roll-out, as minimal changes are expected between this seed and September 25's public release.

In general, High Sierra is a significant update under the hood, but it's light on highly visible changes for general users. We're looking at quality-of-life stuff and foundations for future developments. That doesn't mean there's nothing for Mac app and game developers to dive into, though. Features of the final version of High Sierra include a new proprietary file system, HEVC video support, the Metal 2 graphics API, and myriad tweaks to various apps and services. It will be the first update to macOS since 10.12.6 on July 19.

The file system, called APFS, will be the new default file system in macOS. By default, it will convert any SSD Mac to which it is installed. APFS has numerous advantages over the current HFS+ file system, the original version of which was first introduced to the Mac in Mac OS 8.1 back in 1998. It offers improved encryption options and better SSD support. Ars has reported in detail about the snapshots feature, which now makes file system state saving far more space-efficient by only recording the changes, not copying an entire file.

H.265, also known as HEVC, is the successor to H.264/AVC. It’s a relatively new video-compression standard that promises up to 40-percent better compression by increasing the maximum coding tree block unit from 16x16 pixels to 64x64 pixels, among other things. This makes things more efficient when working in 4K and 8K resolutions, in particular, as opposed to standard HD.

Metal 2 promises a significant performance improvement over Metal, the graphics API that Apple is currently trying to push on Macs to get developers off of the less-than-ideal OpenGL and to compete with DirectX and now Vulkan. The improvements are expected to reduce required draw calls and make rendering on Macs more efficient in several ways. Apple had VR in mind when improving the pipeline, though this release essentially marks the very beginning of VR support in macOS, so there's a lot of ground to cover.

You can download the High Sierra GM now from the Apple developer site, provided you have an Apple ID in the Apple Developer Program or Apple Developer Enterprise Program.