perf: SCStream configuration hygiene (queue depth, sRGB, opaque)#11
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divanshu-go wants to merge 1 commit into
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perf: SCStream configuration hygiene (queue depth, sRGB, opaque)#11divanshu-go wants to merge 1 commit into
divanshu-go wants to merge 1 commit into
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Three SCStreamConfiguration settings for every stream this crate
creates (persistent screenshot + high-fps HD), each with an
independent motivation:
- queue_depth(3): each retained queue slot pins an IOSurface, and both
the latch and push consumers only ever want the newest frame. 3 is
the OS minimum/recommended floor — set it explicitly so a future SDK
default change can't silently grow resident memory.
- Explicit sRGB color space: without it, frames arrive in the
display's native color space (Display P3 on modern Macs), every
consumer pays an implicit conversion, and untagged JPEGs written
downstream (assumed sRGB by viewers) render subtly wrong. sRGB at
the source means WindowServer converts once, on the GPU.
- should_be_opaque(true), gated behind macos_available("14.0") where
the property exists (unguarded, the selector throws
unrecognized-selector on 12.3–13.x — same pattern as the existing
set_show_mouse_clicks guard): display captures have no meaningful
alpha, so the compositor can skip alpha premultiply work per frame.
Behavior note: on P3 displays captured pixel values change slightly
(they were previously P3 values in untagged buffers). Grayscale-based
consumers (Vision OCR) are unaffected; stored JPEGs now render more
accurately in viewers that assume sRGB.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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What
Three
SCStreamConfigurationsettings for every stream this crate creates (persistent screenshot + high-fps HD).queue_depth(3)should_be_opaque(true), gatedmacos_available("14.0")set_show_mouse_clickspattern).