---
title: metric
---

<div class="python-reference">
<a id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric-classes"></a>
<a id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric-functions"></a>
<a id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric"></a>
<p>AudioBox Aesthetics (CE, CU, PC, PQ).</p>
<p>Thin wrapper around Meta's <code>audiobox_aesthetics</code> predictor. Returns
four per-clip dimensions (CE — Content Enjoyment, CU — Content
Usefulness, PC — Production Complexity, PQ — Production Quality);
<code>score</code> exposes PQ, the dimension V2A papers typically report on.
The remaining three are surfaced under <code>details</code>.</p>
<p>The earlier Verse-Bench combined score <code>(CE + CU + PQ + (11 − PC)) / 4</code>
is non-standard and is deliberately not used.</p>
<h2 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric</code></h2>
<pre class="doc-signature"><code>BaseMetric()</code></pre>
<p>Abstract base class for all eval metrics.</p>
<p>Two execution shapes:</p>
<ul>
<li>
<p><strong>Per-sample</strong> (<code>is_set_metric=False</code>, default) — implement
  :meth:<code>compute</code>. The Evaluator calls it once per input sample and
  returns one :class:<code>MetricResult</code> per sample.</p>
</li>
<li>
<p><strong>Set-vs-set</strong> (<code>is_set_metric=True</code>) — implement
  :meth:<code>accumulate</code> (called once per sample to buffer features)
  and :meth:<code>finalize</code> (called once after all samples to compute
  the corpus-level result). Use :meth:<code>reset</code> to clear buffers and
  :meth:<code>merge_from</code> to fold multi-GPU per-worker state together.</p>
</li>
</ul>
<p>Optionally override :meth:<code>setup</code> to eagerly load models. Metrics
that chunk along the time dim for memory hardcode their own chunk
size in <code>__init__</code> (see <code>optical_flow</code> for the canonical
example). Eval always processes one video per
:meth:<code>Evaluator.evaluate</code> call; <code>compute</code> / <code>accumulate</code>
receive a single sample, not a batch.</p>

<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.to"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.to</code></h3>
<pre class="doc-signature"><code>to(device: str | torch.device) -&gt; BaseMetric</code></pre>
<p>Move metric (and its internal models) to <em>device</em>.</p>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.setup"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.setup</code></h3>
<pre class="doc-signature"><code>setup() -&gt; None</code></pre>
<p>Eagerly load models. Called once by :class:<code>EvalWorker</code>.</p>
<p>Default is a no-op; metrics with no eager state (pixel math,
closed-form ops) inherit this. Override only if your metric
needs to load weights.</p>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.compute"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.compute</code></h3>
<pre class="doc-signature"><code>compute(sample: dict) -&gt; MetricResult</code></pre>
<p>Per-sample metrics: compute the score for one sample.</p>
<p><code>sample["video"]</code> is <code>(T, C, H, W)</code> float in <code>[0, 1]</code>.
<code>sample["reference"]</code> (if used) has the same shape. Return
<code>self._skip(sample, reason)</code> for missing inputs.</p>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.reset"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.reset</code></h3>
<pre class="doc-signature"><code>reset() -&gt; None</code></pre>
<p>Clear accumulator state at the start of each evaluate() call.</p>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.accumulate"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.accumulate</code></h3>
<pre class="doc-signature"><code>accumulate(sample: dict) -&gt; None</code></pre>
<p>Buffer per-sample features for a corpus-level metric.</p>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.finalize"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.finalize</code></h3>
<pre class="doc-signature"><code>finalize() -&gt; MetricResult</code></pre>
<p>Compute the corpus-level result from buffered state.</p>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.merge_from"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.BaseMetric.merge_from</code></h3>
<pre class="doc-signature"><code>merge_from(other: BaseMetric) -&gt; None</code></pre>
<p>Multi-GPU: fold another worker's accumulator state into this one.</p>
<h2 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.register"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.register</code></h2>
<pre class="doc-signature"><code>register(name: str)</code></pre>
<p>Decorator to register a metric class.</p>
<p>Usage::</p>
<pre><code>@register("ssim")
class SSIMMetric(BaseMetric):
    ...
</code></pre>
<h2 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.MetricResult"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.MetricResult</code></h2>
<pre class="doc-signature"><code>MetricResult(name: str, score: float | None, details: dict&#91;str, Any&#93; = dict())</code></pre>
<p>Standard result container returned by all metrics.</p>
<p><code>score</code> is <code>None</code> when the metric was skipped (e.g. missing
required input).  Check <code>details["skipped"]</code> for the reason.</p>

<h2 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric</code></h2>
<pre class="doc-signature"><code>AudioBoxAestheticsMetric()</code></pre>
<p>AudioBox Aesthetics: PQ as the primary score, CE/CU/PC/PQ in details.</p>

<details><summary>Source</summary><pre><code>@register(&quot;audio.audiobox_aesthetics&quot;)
class AudioBoxAestheticsMetric(BaseMetric):
    &quot;&quot;&quot;AudioBox Aesthetics: PQ as the primary score, CE/CU/PC/PQ in details.&quot;&quot;&quot;

    name = &quot;audio.audiobox_aesthetics&quot;
    requires_reference = False
    higher_is_better = True
    needs_gpu = True
    is_set_metric = False
    dependencies = &#91;&quot;audiobox_aesthetics&quot;&#93;

    def __init__(self) -&gt; None:
        super().__init__()
        self._predictor: Any = None

    def to(self, device):
        super().to(device)
        if self._predictor is not None:
            self._predictor.model.to(self.device)
            self._predictor.device = self.device
        return self

    def setup(self) -&gt; None:
        if self._predictor is not None:
            return
        from audiobox_aesthetics.infer import initialize_predictor
        predictor = initialize_predictor()
        # Upstream&#x27;s setup_model() always lands on default CUDA (cuda:0).
        # Re-pin onto this worker&#x27;s device so multi-GPU eval actually parallelizes.
        predictor.model.to(self.device)
        predictor.device = self.device
        self._predictor = predictor

    @torch.no_grad()
    def compute(self, sample: dict) -&gt; MetricResult:
        from pathlib import Path

        if self._predictor is None:
            self.setup()

        audio_path = sample.get(&quot;audio&quot;)
        if audio_path is None:
            return self._skip(sample, &quot;missing &#x27;audio&#x27;&quot;)
        if not Path(audio_path).exists():
            return self._skip(sample, f&quot;audio file not found: &#123;audio_path&#125;&quot;)

        try:
            score = self._predictor.forward(&#91;&#123;&quot;path&quot;: audio_path&#125;&#93;)&#91;0&#93;
        except Exception as exc:  # pragma: no cover — upstream raises vary
            return self._skip(sample, f&quot;audiobox predictor failed: &#123;type(exc).__name__&#125;: &#123;exc&#125;&quot;)
        try:
            return MetricResult(
                name=self.name,
                score=float(score&#91;&quot;PQ&quot;&#93;),
                details=&#123;
                    &quot;CE&quot;: float(score&#91;&quot;CE&quot;&#93;),
                    &quot;CU&quot;: float(score&#91;&quot;CU&quot;&#93;),
                    &quot;PC&quot;: float(score&#91;&quot;PC&quot;&#93;),
                    &quot;PQ&quot;: float(score&#91;&quot;PQ&quot;&#93;),
                &#125;,
            )
        except (KeyError, TypeError) as exc:
            return self._skip(sample, f&quot;audiobox returned unexpected shape: &#123;exc&#125;&quot;)</code></pre></details>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric.to"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric.to</code></h3>
<pre class="doc-signature"><code>to(device)</code></pre>

<details><summary>Source</summary><pre><code>def to(self, device):
    super().to(device)
    if self._predictor is not None:
        self._predictor.model.to(self.device)
        self._predictor.device = self.device
    return self</code></pre></details>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric.setup"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric.setup</code></h3>
<pre class="doc-signature"><code>setup() -&gt; None</code></pre>

<details><summary>Source</summary><pre><code>def setup(self) -&gt; None:
    if self._predictor is not None:
        return
    from audiobox_aesthetics.infer import initialize_predictor
    predictor = initialize_predictor()
    # Upstream&#x27;s setup_model() always lands on default CUDA (cuda:0).
    # Re-pin onto this worker&#x27;s device so multi-GPU eval actually parallelizes.
    predictor.model.to(self.device)
    predictor.device = self.device
    self._predictor = predictor</code></pre></details>
<h3 id="fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric.compute"><code>fastvideo.eval.metrics.audio.audiobox_aesthetics.metric.AudioBoxAestheticsMetric.compute</code></h3>
<pre class="doc-signature"><code>compute(sample: dict) -&gt; MetricResult</code></pre>

<details><summary>Source</summary><pre><code>@torch.no_grad()
def compute(self, sample: dict) -&gt; MetricResult:
    from pathlib import Path

    if self._predictor is None:
        self.setup()

    audio_path = sample.get(&quot;audio&quot;)
    if audio_path is None:
        return self._skip(sample, &quot;missing &#x27;audio&#x27;&quot;)
    if not Path(audio_path).exists():
        return self._skip(sample, f&quot;audio file not found: &#123;audio_path&#125;&quot;)

    try:
        score = self._predictor.forward(&#91;&#123;&quot;path&quot;: audio_path&#125;&#93;)&#91;0&#93;
    except Exception as exc:  # pragma: no cover — upstream raises vary
        return self._skip(sample, f&quot;audiobox predictor failed: &#123;type(exc).__name__&#125;: &#123;exc&#125;&quot;)
    try:
        return MetricResult(
            name=self.name,
            score=float(score&#91;&quot;PQ&quot;&#93;),
            details=&#123;
                &quot;CE&quot;: float(score&#91;&quot;CE&quot;&#93;),
                &quot;CU&quot;: float(score&#91;&quot;CU&quot;&#93;),
                &quot;PC&quot;: float(score&#91;&quot;PC&quot;&#93;),
                &quot;PQ&quot;: float(score&#91;&quot;PQ&quot;&#93;),
            &#125;,
        )
    except (KeyError, TypeError) as exc:
        return self._skip(sample, f&quot;audiobox returned unexpected shape: &#123;exc&#125;&quot;)</code></pre></details>
</div>
