Function backend_output_caps 

pub fn backend_output_caps(backend: EncoderBackend) -> OutputCaps

Output capabilities of a specific hardware backend. All three do 10-bit AV1, so they can produce HDR without the ffmpeg feature: NVENC via Yuv420_10bit, AMF via P010, and QSV via the in-repo oneVPL P010 path ([qsv_p010]).