The Windows direct-NVENC backend registers and encodes the capturer's textures
IN PLACE (no CopyResource), so how deep it may pipeline is a property of the
CAPTURER, not of the encoder. It was bounded only by `async_inflight_cap()` —
`PUNKTFUNK_NVENC_ASYNC_DEPTH`, default 4, clamped to the output-bitstream pool
— which consults nothing about the capturer, while the comment at the
backpressure loop claimed it "keep[s] in-flight depth within the capturer's
texture ring". It never did.
The IDD-push capturer rotates `OUT_RING = 3` per delivered frame with no regard
for encode completion (its own invariant note says OUT_RING(3) > max
pipeline_depth(2)). With the default async depth of 4 the encoder can therefore
still be reading a texture the capturer has already handed out again and
overwritten: torn or mixed frames. It is visual corruption rather than UB, so it
fails silently and intermittently — the worst shape to diagnose from a field
report.
Adds `Encoder::set_input_ring_depth`, reported from `Capturer::pipeline_depth`,
and bounds the async backpressure loop by `min(async_inflight_cap(), depth)`.
For IDD-push that yields 2, matching the capturer's stated contract; backends
that copy their input, or are synchronous, ignore it.
Wired at ALL THREE encoder-creation sites (initial open, stall/resize rebuild,
ABR rebuild) and forwarded through `TrackedEncoder` — this crate has a
documented trap where an unforwarded defaulted trait method silently no-ops
through that wrapper, which has already bitten the direct-NVENC work once and
the wire-chunking probe once.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
enricobuehler
6f52397342