hao-ai-lab-FastVideo/fastvideo/eval

fastvideo.eval

In-process evaluation suite for video and world-model generations. Native metrics (SSIM, PSNR, LPIPS, optical flow), audio metrics, the full VBench suite, physics_iq, and a small VLM scorer all live behind a single registry-driven API.

Install

Eval lives in FastVideo's main venv. Add the eval extras:

pip install -e .[eval]

To use VBench specifically, also pull the upstream submodule:

git submodule update --init --recursive  # fetches vbench + kernel deps

That's the entire setup. There is no eval-specific bootstrap script. The submodule is a clean upstream pin; modern-dep compat is achieved at import time, in fastvideo/eval/metrics/vbench/__init__.py, by attribute-level monkey-patches against transformers, numpy, and timm. Nothing on disk in the submodule is modified.

Public API

from fastvideo.eval import (
    create_evaluator,        # build a reusable Evaluator
    evaluate,                # one-shot helper
    Evaluator,               # the class itself
    BaseMetric, MetricResult,
    register, list_metrics, get_metric,
    ensure_checkpoint, get_cache_dir,
)

ev = create_evaluator(metrics=["common.ssim", "vbench.aesthetic_quality"],
                      device="cuda")
scores = ev.evaluate(video=tensor, reference=ref, fps=8.0)

CLI

fastvideo eval list                              # list registered metrics
fastvideo eval list --group vbench               # filter by group
fastvideo eval run --videos clip.mp4 \
    --metrics vbench.aesthetic_quality \
    --output scores.json
fastvideo eval run --videos generated/*.mp4 \
    --reference reference/ \
    --metrics common.ssim,common.lpips

Generate-then-score example

examples/inference/eval/eval_ltx2_vbench.py runs an LTX2 prompt through VideoGenerator and scores the resulting mp4 with vbench.aesthetic_quality and vbench.subject_consistency. Use it as a template for end-to-end "generate → score" pipelines.

Layout

fastvideo/
├── eval/
│   ├── api.py, evaluator.py, registry.py, models.py, ...
│   ├── io/                        # video loading helpers
│   └── metrics/
│       ├── base.py                # BaseMetric + @register contract
│       ├── common/                # SSIM, PSNR, LPIPS, optical_flow
│       ├── audio/                 # CLAP, WER, audiobox, ...
│       ├── vlm/                   # VideoScore-2
│       ├── physics_iq/            # PhysicsIQ + sub-metrics
│       └── vbench/                # ← adapter: sys.path bootstrap + shims
│           ├── __init__.py
│           └── <16 sub-metric pkgs>
└── third_party/
    └── eval/
        └── vbench/                # ← git submodule (Vchitect/VBench)

Adding a new metric

The full porting guide is at docs/contributing/eval-metrics.md. Summary below.

Native, no submodule

# fastvideo/eval/metrics/common/<your_metric>/metric.py
from fastvideo.eval.metrics.base import BaseMetric
from fastvideo.eval.registry import register
from fastvideo.eval.types import MetricResult


@register("common.your_metric")
class YourMetric(BaseMetric):
    name = "common.your_metric"
    requires_reference = True
    needs_gpu = False
    dependencies: list[str] = []  # add e.g. ["pyiqa"] if relevant

    def compute(self, sample) -> list[MetricResult]:
        ...

The metric is auto-discovered by fastvideo/eval/metrics/__init__.py (walks all non-underscore subdirectories and imports their metric module).

With a submodule for upstream code

Pattern: see fastvideo/eval/metrics/vbench/. The contract is:

1. <bench>/external/upstream/ is a git submodule pinned to a SHA (registered in repo-root .gitmodules).
2. <bench>/__init__.py inserts that path on sys.path and installs any compat shims (attribute-level monkey-patches) needed for modern torch/transformers/numpy. Do not modify upstream files on disk.
3. Per-sub-metric metric.py files use @register("<bench>.<name>").

There is no per-benchmark setup script. Patches live as Python in the metric's __init__.py, where they are grep-able and reviewable.

Caches

Eval cache root: ${FASTVIDEO_CACHE_ROOT}/eval/ (default ~/.cache/fastvideo/eval/). Override with FASTVIDEO_EVAL_CACHE.

${FASTVIDEO_CACHE_ROOT}/eval/
├── models/      # URL-fetched checkpoints (LAION head, AMT, GRiT)
├── torch/       # redirected TORCH_HOME (DINO via torch.hub, lpips)
└── clip/        # passed as download_root= to clip.load callsites

HF-hosted models stay in HF's default cache (~/.cache/huggingface/hub/) so they dedupe with other ML projects on the same host.

Convention for new metrics

If your metric wraps a third-party loader that has its own cache directory, route it through get_cache_dir() so users get one knob:

# CLIP — pass download_root explicitly
import clip
from fastvideo.eval.models import get_cache_dir
model, _ = clip.load("ViT-B/32", device=device,
                     download_root=str(get_cache_dir() / "clip"))

# torch.hub — already redirected by fastvideo.eval.__init__
# via TORCH_HOME; no per-callsite work needed.

# transformers / huggingface_hub — leave alone; HF's default cache
# is shared with other tools.

Libraries with non-standard caches that don't honour any env var or kwarg (pyiqa, funasr) currently land in their own dirs. Acceptable for now; document in the metric's docstring if it matters.

Out of scope (follow-up PRs)

• MIND metrics — depend on a separate vipe upstream submodule.
• VBench-2.0 — sibling vbench2 package; needs its own port.
• FVD as a registered metric — currently still at benchmarks/fvd/; FVD is fundamentally a set-vs-set distribution distance and doesn't fit the per-sample BaseMetric.compute API without a stateful accumulator. Conversion is a designed follow-up.
• Training-time eval callback (EvalCallback) and the RolloutEvaluator helper.