Covers. Art out of an ID3 APIC frame is sized for a record sleeve: this library
averaged 3000x3000 and 580 kB per cover, 140 MB across 284 albums. The browser was
decoding nine megapixels - around 36 MB of bitmap - for every cover it painted, to show
it in a 185 px card, on a Pi with 2 GB of RAM. The largest any screen in this app asks
for is 340 px (the play view), so cache.store_cover now downscales to a 640 px long
edge, which leaves room for a tablet at devicePixelRatio 2 and cuts the decode about
twentyfold. Pillow was already a hard dependency, for colour extraction.
scan_library reuses an album whose fingerprint is unchanged without re-reading its
tags, so covers already on disk would never be rewritten - hence shrink_stored_covers(),
a pass at the top of a scan. Reading a JPEG's dimensions only parses its header, so
after the first run it costs one small read per album. Art already small enough is
returned byte-identical rather than re-encoded, so repeated scans cannot slowly grind
it down, and anything Pillow cannot read is passed through untouched: a cover that is
too big is a performance problem, a cover that is missing is a visible one.
Animation. Halving the ambient canvas to a quarter of the pixels at 30fps took it from
53.5% of a core to 25%, and 25% was still not good enough to use. A requestAnimationFrame
loop repainting the viewport is a floor you cannot get under while it runs at all, so
?pi=1 now switches it off outright rather than thinning it, along with the decorative
CSS loops, the view transitions, the typing game's bubbles and its next-key pulse. The
pets stay on screen but hold still, through the same path prefers-reduced-motion already
took - taking the animation away is the point, taking away what she earned is not.
.stage keeps its own static gradient, so there is still a sea behind everything.
Both blurs on the panels stay on. Dropping those measured five times worse.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Martin Bauer
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