`sws_getContext` hands back a raw pointer whose only `sws_freeContext` lives in
`Drop for NvencEncoder` — and `Drop` needs a CONSTRUCTED `Self`, which does not
exist on either of `open`'s early returns: the intra-refresh-unsupported path
(which recurses into `Self::open`) and the plain error return. Both sit between
the context's creation and the `Ok(NvencEncoder { … })` that would give it an
owner, so every failed open leaked one.
That is not a once-per-process wart. `open_nvenc_probed` walks an EINVAL bitrate
ladder — requested rate, then the codec-level cap, then ×3/4 down to 50 Mb/s —
re-entering `open` at each step, so a GPU that refuses the requested bitrate leaks
a context per step (up to ~10). The intra-refresh retry adds one more.
Fixed structurally rather than with a guard: the block depends only on values known
before the encoder open (`want_444`, `want_hdr10`, `cuda`, `format`, `nvenc_pixel`,
the dimensions, `full_range_444`), so moving it BELOW `video.open_with(opts)` — to
just above the struct construction, with nothing fallible in between — makes the
leak unrepresentable instead of merely handled. No behaviour change: same context,
same colourspace details, same field.
Found while designing the WP1.4 swscale expand, which would have promoted this from
a 4:4:4/HDR-only leak (the only sessions that build a context today) to one on every
packed-RGB session. Fixing it first is the prerequisite for that change.
Verified `-D warnings --all-targets` + tests on Linux (default; shipped
nvenc+vulkan-encode+pyrowave).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
enricobuehlerandClaude Opus 5
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