AetherEngine 2.1.1

FrameExtractor quality pass. Internal only, no public API change. Existing 2.1.0 callers are unaffected.

Fixed / Improved

HDR thumbnails now tone-map correctly. PQ (ST 2084) and HLG stills used to come out too dark / desaturated because the extractor scaled straight to sRGB with no transfer conversion. HDR frames now route through a zscale + tonemap libavfilter graph (BT.2020 PQ/HLG to SDR BT.709 RGBA, hable tone curve); SDR keeps the fast direct sws path. This relies on the avfilter + zimg additions to FFmpegBuild (already pinned by this release).

Faster, lighter remote extraction. A new .stillExtraction demuxer profile gives the extractor's AVIO a random-access shape: no read-ahead prefetch (a scrub discards it on the next seek, and it competed with playback bandwidth), a 1 MB seek chunk, and a small probe budget. Decode fast-flags (skip loop filter, fast decode) cut per-frame CPU on big HEVC keyframes.

Thumbnails fixed on sparse-keyframe HEVC. The thumbnail decode no longer sets skip_frame = NONKEY, which starved the decoder when a seek landed mid-GOP past a lone keyframe and produced nil thumbnails on some HEVC sources.

Verification

Build + full test suite green; leaks --atExit reports 0 leaks across repeated HDR extractions (the per-call filter graph is freed each time); SDR and HDR thumbnail / snapshot all produce images via aetherctl extract.

Known limitation

DV Profile 5 (IPT-PQ, no HDR10 base) thumbnails still render with wrong colours on the software decode path the extractor uses, the same class as the AV1 Profile 10.0 limitation. Full Profile 5 playback is unaffected (it routes through the native AVPlayer path).

Full changelog: 2.1.0...2.1.1