`ffmpeg -encoders` lists every compiled-in encoder — a full Windows
build advertises h264_nvenc/qsv/amf even when the machine has none of
that hardware — so probe_hw_encoder picked NVENC on the GPU-less Windows
runner and the proxy transcode failed ('Cannot load libcuda.so.1',
caught by engine_proxy_generate_and_delete now that the Windows package
ships an ffmpeg CLI). Probe a one-frame null encode per candidate and
fall through to the next, finally to libx264.
Reproduced locally with a full ffmpeg build: h264_nvenc exits 255
without the driver, libx264 succeeds.
Mike-Solar
e27bc690f1