- Exported HEVC/AV1 nclx says BT.709 and limited range where the pipeline
means it, matching what the players we tested assume; the round-trip
tests pin the box values.
- The ffmpeg oracle helpers no longer read the flags column of
`ffmpeg -decoders` for "is a decoder" — every row of that listing is a
decoder, and the trailing D there is "supports direct rendering method
1", which a build's hevc decoder may legitimately lack. Decoders are
matched by the codec-name column alone.
- Fixtures a given ffmpeg build cannot actually encode (a listed encoder
that fails at run time: hardware backends without their device, the
noopenh264 stub) skip with a note instead of failing the run.