The libva guard fired: the release ffmpeg had no h264_vaapi. ffmpeg-sys-next
configures with --disable-autodetect and only passes --enable-vaapi when its
build-vaapi feature is set; ffmpeg-next 8.0 doesn't forward it, so installing
libva-dev alone did nothing.
Inject a direct ffmpeg-sys-next dependency with the build-vaapi feature
(Linux only) in both the GitHub Actions and container build paths. With it,
FFmpeg gets --enable-vaapi (and fails loudly if libva-dev is missing rather
than silently shipping software-only).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Skyler Lehmkuhl