Tiny AI is the part of VMAFx that runs small ONNX perceptual-quality models next to the classic VMAF SVM. A tiny model can replace or augment the SVM score (full-reference), score a clip without a reference, or filter frames before encoding. libvmaf stays C-only: models run through ONNX Runtime, and training lives in the Python package ai/.
You need a libvmaf build with ONNX Runtime (-Denable_dnn=enabled, or auto with ONNX Runtime found by pkg-config). --tiny-model takes the path of an .onnx file, not a registry id. Models ship under model/tiny/.
The tiny score is an ordinary per-frame feature in the output. It is named after the name field of the model's sidecar JSON, or vmaf_tiny_model when the sidecar has no name. Look for it in frames[].metrics and pooled_metrics next to vmaf. Full details, flags and caveats are in inference.md.
Note
Models that read libvmaf features (the vmaf_tiny_* and fr_regressor_* families) make the run compute them, and their scores appear once the run has read its last frame. The codec-aware fr_regressor_v2 and fr_regressor_v3 also need --tiny-codec and --tiny-crf (inference).
The shipped models were trained against the vmaf_v0.6.1 teacher, and model/tiny/registry.json lists 26 entries, 13 of them smoke fixtures that exercise the loader and are not quality models. The one-shot retrain against the vmaf_v1.0.16_3d0h teacher is RC9 work, see the roadmap and the retrain runbook. Treat accuracy numbers as pre-retrain.