A Coding Guide to Google Research’s MSEB: Writing Sound Encoders to the Benchmark Contract and Scoring Them Across Classification, Clustering, Retrieval and Segmentation

import os
import sys
import json
import math
import traceback
import subprocess
import numpy as np
RESULTS = {}
BENCH = {}
def banner(title):
    print("\n" + "=" * 78)
    print(title)
    print("=" * 78)
def section(name):
    def wrap(fn):
        def run(*a, **kw):
            banner(name)
            try:
                out = fn(*a, **kw)
                RESULTS[name] = out if isinstance(out, str) else "ok"
                return out
            except Exception as e:
                RESULTS[name] = f"SKIPPED / FAILED -> {type(e).__name__}: {e}"
                print(f"\n[!] {name} did not complete: {type(e).__name__}: {e}")
                traceback.print_exc(limit=3)
                return None
        return run
    return wrap
banner("0. Install MSEB and map the three layers we will use")
subprocess.run([sys.executable, "-m", "pip", "install", "-q", "mseb==0.1.0"], check=True)
import mseb
from mseb import types, encoder as encoder_lib, evaluator as evaluator_lib, metrics
from mseb.evaluators import (
    classification_evaluator,
    clustering_evaluator,
    retrieval_evaluator,
    segmentation_evaluator,
)
print(f"  mseb {mseb.__version__}  |  Python {sys.version.split()[0]}  |  numpy {np.__version__}")
print("\n  MSEB is three layers, and a benchmark run walks down them:")
print("    types      -> Sound, SoundEmbedding, Score, TaskMetadata: the shapes every task speaks")
print("    encoder    -> MultiModalEncoder: the contract YOUR model implements")
print("    evaluators -> classification, clustering, retrieval, reranking, transcription, segmentation, ...")
print("\n  evaluator entry points we will drive:")
for module, cls in [(classification_evaluator, "ClassificationEvaluator"),
                    (clustering_evaluator, "ClusteringEvaluator"),
                    (retrieval_evaluator, "RetrievalEvaluator"),
                    (segmentation_evaluator, "SegmentationEvaluator")]:
    print(f"    {module.__name__.split('.')[-1]:28s} {cls}")
print("\n  Everything below runs on CPU with no dataset download: we synthesise the audio.")

SR = 16000
@section("1. The type contract: Sound, SoundEmbedding, Score")
def type_contract():
    t = np.arange(SR) / SR
    waveform = (0.5 * np.sin(2 * np.pi * 440 * t)).astype(np.float32)
    sound = types.Sound(
        waveform=waveform,
        context=types.SoundContextParams(id="demo_000", sample_rate=SR, length=len(waveform),
                                         language="en_us", text="a 440 Hz tone"),
    )
    print(f"  Sound          id={sound.context.id!r}  {sound.waveform.shape} @ {sound.context.sample_rate} Hz"
          f"  -> {sound.size_bytes:,} bytes")
    embedding = types.SoundEmbedding(
        embedding=np.zeros((1, 16), dtype=np.float32),            # (N, D): one utterance-level vector
        timestamps=np.array([[0.0, 1.0]], dtype=np.float32),      # (M, 2): [start, end] in seconds
        context=sound.context,
        encoding_stats=types.EncodingStats(input_size_bytes=sound.size_bytes, embedding_size_bytes=16 * 4),
    )
    print(f"  SoundEmbedding embedding{embedding.embedding.shape}  timestamps{embedding.timestamps.shape}"
          f"  -> {embedding.size_bytes} bytes")
    print(f"                 compression_ratio = {embedding.encoding_stats.compression_ratio:.5f}"
          f"  ({1 / embedding.encoding_stats.compression_ratio:,.0f}x smaller than the audio)")
    print("  N embeddings and M timestamps: M == N is frame-aligned, M == 1 is utterance-level.")
    print("  `embedding` may also hold N strings instead of vectors - step 8 uses exactly that.")
    score = types.Score(metric="Accuracy", description="Overall classification accuracy",
                        value=0.875, min=0.0, max=1.0)
    print(f"\n  Score          {score.metric}={score.value} in [{score.min}, {score.max}] :: {score.description}")
    for bad, why in [(dict(metric="", description="d", value=0.5, min=0.0, max=1.0), "empty metric name"),
                     (dict(metric="m", description="d", value=0.5, min=1.0, max=0.0), "min > max")]:
        try:
            types.Score(**bad)
        except Exception as e:
            print(f"  rejected at construction ({why}): {type(e).__name__}: {e}")
    return f"Sound {sound.size_bytes:,} B -> embedding {embedding.size_bytes} B"
type_contract()

class EnergyEnvelopeEncoder(encoder_lib.MultiModalEncoder):
    """Baseline: average energy in `n_bins` equal time slices. Loud/quiet, nothing about timbre."""
    def __init__(self, n_bins: int = 16):
        super().__init__()
        self.n_bins = n_bins
    def _setup(self):
        self._ready = True                                    # a real encoder loads weights here
    def _check_input_types(self, batch):
        for item in batch:
            if not isinstance(item, types.Sound):
                raise ValueError(f"{type(self).__name__} takes types.Sound, got {type(item).__name__}")
    def _encode(self, batch) -> list[types.SoundEmbedding]:
        out = []
        for sound in batch:
            slices = np.array_split(sound.waveform.astype(np.float32), self.n_bins)
            vec = np.array([[float(np.sqrt(np.mean(s ** 2) + 1e-12)) for s in slices]], dtype=np.float32)
            vec /= np.linalg.norm(vec) + 1e-9
            out.append(types.SoundEmbedding(
                embedding=vec,
                timestamps=np.array([[0.0, sound.context.length / sound.context.sample_rate]], dtype=np.float32),
                context=sound.context))
        return out
class SpectralProfileEncoder(encoder_lib.MultiModalEncoder):
    """Contender: mean log-magnitude spectrum pooled into `n_bands` bands. Describes timbre."""
    def __init__(self, n_bands: int = 16, frame: int = 512):
        super().__init__()
        self.n_bands, self.frame = n_bands, frame
    def _setup(self):
        self._window = np.hanning(self.frame).astype(np.float32)
    def _check_input_types(self, batch):
        for item in batch:
            if not isinstance(item, types.Sound):
                raise ValueError(f"{type(self).__name__} takes types.Sound, got {type(item).__name__}")
    def _encode(self, batch) -> list[types.SoundEmbedding]:
        out = []
        for sound in batch:
            w = sound.waveform.astype(np.float32)
            n_frames = max(1, len(w) // self.frame)
            spectra = [np.abs(np.fft.rfft(w[i * self.frame:(i + 1) * self.frame] * self._window))
                       for i in range(n_frames)]
            mean_spectrum = np.log1p(np.mean(spectra, axis=0))
            vec = np.array([[float(b.mean()) for b in np.array_split(mean_spectrum, self.n_bands)]],
                           dtype=np.float32)
            vec /= np.linalg.norm(vec) + 1e-9
            out.append(types.SoundEmbedding(
                embedding=vec,
                timestamps=np.array([[0.0, sound.context.length / sound.context.sample_rate]], dtype=np.float32),
                context=sound.context))
        return out
@section("2. The encoder contract: three methods, and the framework does the rest")
def encoder_contract():
    print("  MultiModalEncoder abstract methods a subclass must implement:")
    for name in sorted(encoder_lib.MultiModalEncoder.__abstractmethods__):
        print(f"    {name}")
    print("  final (framework-owned, do not override): setup(), encode()")
    t = np.arange(SR) / SR
    fade = np.exp(-2.5 * t).astype(np.float32)                # a decaying note, so the envelope is not flat
    sound = types.Sound(waveform=(0.5 * fade * np.sin(2 * np.pi * 440 * t)).astype(np.float32),
                        context=types.SoundContextParams(id="demo_000", sample_rate=SR, length=SR))
    for enc in (EnergyEnvelopeEncoder(), SpectralProfileEncoder()):
        enc.setup()
        emb = enc.encode([sound])[0]
        stats = emb.encoding_stats                            # attached by encode(), not by our code
        print(f"\n  {type(enc).__name__:24s} -> {emb.embedding.shape} {emb.embedding.dtype}"
              f"   output_type={enc.output_type().__name__}")
        print(f"  {'':24s}    EncodingStats(input={stats.input_size_bytes:,} B, "
              f"embedding={stats.embedding_size_bytes} B, flops={stats.flops})")
        print(f"  {'':24s}    first 6 dims: {np.round(emb.embedding[0][:6], 3)}")
    print("\n  The envelope encoder sees the note decay; the spectral encoder sees one peak at 440 Hz.")
    try:
        EnergyEnvelopeEncoder().encode(["not a Sound"])
    except ValueError as e:
        print(f"\n  wrong input type is caught by _check_input_types: {e}")
    return "two encoders satisfying MultiModalEncoder"
encoder_contract()

CLASSES = ["tone", "chirp", "noise"]
N_PER_CLASS = 12
def synthesize(kind: str, index: int, take: int) -> types.Sound:
    """One second of audio. `take` 0 is the document, take 1 is a noisier recording of the SAME clip.
    Two cues are deliberately separated: the spectrum says which class it is, and the amplitude
    envelope - drawn per item, independent of class - says which item it is.
    """
    item = np.random.default_rng(1000 + CLASSES.index(kind) * 100 + index)
    control = 0.25 + 0.75 * item.random(8)
    envelope = np.interp(np.linspace(0, 7, SR), np.arange(8), control).astype(np.float32)
    t = np.arange(SR) / SR
    if kind == "tone":
        w = np.sin(2 * np.pi * (380 + 80 * item.random()) * t)
    elif kind == "chirp":
        f0, f1 = 200 + 50 * item.random(), 3200 + 400 * item.random()
        w = np.sin(2 * np.pi * (f0 * t + 0.5 * (f1 - f0) * t ** 2))
    else:
        w = item.standard_normal(SR)
    w /= np.sqrt(np.mean(w ** 2)) + 1e-9                      # unit RMS: the envelope is the only loudness cue
    take_rng = np.random.default_rng(50_000 + take * 10_000 + CLASSES.index(kind) * 100 + index)
    w = (0.4 + 0.2 * take_rng.random()) * envelope * (w + 0.02 * take_rng.standard_normal(SR))
    return types.Sound(waveform=w.astype(np.float32), context=types.SoundContextParams(
        id=f"{kind}_{index:02d}" + ("" if take == 0 else "_take2"), sample_rate=SR,
        length=SR, language="en_us", text=kind))
@section("3. A synthetic corpus, encoded into MSEB embedding caches")
def build_corpus():
    corpus = [synthesize(k, i, 0) for k in CLASSES for i in range(N_PER_CLASS)]
    queries = [synthesize(k, i, 1) for k in CLASSES for i in range(N_PER_CLASS)]
    labels = {s.context.id: s.context.text for s in corpus + queries}
    print(f"  {len(corpus)} documents + {len(queries)} second takes of the same clips,"
          f" {len(CLASSES)} classes, 1.0s each @ {SR} Hz")
    caches, query_caches = {}, {}
    for enc in (EnergyEnvelopeEncoder(), SpectralProfileEncoder()):
        enc.setup()
        embeddings = enc.encode(corpus)                        # one batched call, like a real runner
        caches[type(enc).__name__] = {e.context.id: e for e in embeddings}
        query_caches[type(enc).__name__] = {e.context.id: e for e in enc.encode(queries)}
        matrix = np.vstack([e.embedding for e in embeddings])
        within, between = [], []
        for i in range(len(corpus)):
            for j in range(i + 1, len(corpus)):
                sim = float(matrix[i] @ matrix[j])
                (within if labels[corpus[i].context.id] == labels[corpus[j].context.id] else between).append(sim)
        print(f"  {type(enc).__name__:24s} cache of {len(embeddings)} embeddings, dim {matrix.shape[1]}"
              f"   mean cosine: same-class {np.mean(within):.3f} vs other-class {np.mean(between):.3f}"
              f"   (gap {np.mean(within) - np.mean(between):+.3f})")
    print("\n  Read that gap as a prediction: only the spectral encoder separates the classes at all.")
    print("  Steps 4-6 check whether the evaluators agree - and whether the gap is the whole story.")
    globals().update(CORPUS=corpus, QUERIES=queries, LABELS=labels, CACHES=caches, QCACHES=query_caches)
    return f"{len(corpus)} documents + {len(queries)} queries encoded by 2 encoders"
build_corpus()

def class_prototypes(cache, labels):
    """Class embedding table (C, D): the mean unit vector of each class, as the evaluator's `weights`."""
    rows = []
    for name in CLASSES:
        vecs = np.vstack([cache[i].embedding for i in cache if labels[i] == name])
        mean = vecs.mean(axis=0)
        rows.append(mean / (np.linalg.norm(mean) + 1e-9))
    return np.vstack(rows).astype(np.float32)
@section("4. ClassificationEvaluator: prototypes in, Score objects out")
def classification():
    table, example = {}, None
    for name, cache in CACHES.items():
        evaluator = classification_evaluator.ClassificationEvaluator(
            class_labels=CLASSES,
            weights=class_prototypes(cache, LABELS),
            distance_fn=evaluator_lib.dot_product,             # embeddings are L2-normalised -> cosine
            top_k_value=2,
        )
        predictions = evaluator.compute_predictions(cache)     # {id: per-class score vector}
        references = [classification_evaluator.ClassificationReference(i, LABELS[i]) for i in cache]
        table[name] = {s.metric: s.value for s in evaluator.compute_metrics(predictions, references)}
        if name == "SpectralProfileEncoder":
            key = next(iter(predictions))
            example = (key, np.round(list(predictions[key]), 3))
    metric_names = list(next(iter(table.values())))[:6]
    print(f"  {'encoder':26s}" + "".join(f"{m[:14]:>16s}" for m in metric_names))
    for name, row in table.items():
        print(f"  {name:26s}" + "".join(f"{row[m]:16.3f}" for m in metric_names))
    print(f"\n  compute_predictions returns one raw score per class, e.g. {example[0]!r} -> {example[1]}")
    print(f"  ({CLASSES} - the argmax is the prediction, and top_k_value=2 also scores Top-2 Accuracy.)")
    print("  compute_metrics turns those into types.Score objects, which is what the leaderboard stores.")
    for name, row in table.items():
        BENCH.setdefault(name, {})["Accuracy"] = row["Accuracy"]
    winner = max(table, key=lambda k: table[k]["Accuracy"])
    return "Accuracy: " + ", ".join(f"{k} {v['Accuracy']:.3f}" for k, v in table.items()) + f" (winner {winner})"
classification()

@section("5. ClusteringEvaluator: no labels at encode time, V-measure at score time")
def clustering():
    evaluator = clustering_evaluator.ClusteringEvaluator()
    examples = [clustering_evaluator.ClusteringExample(sound_id=i, label=LABELS[i])
                for i in next(iter(CACHES.values()))]
    print(f"  {len(examples)} examples, KMeans with k = {len(CLASSES)} (inferred from the labels)")
    for name, cache in CACHES.items():
        np.random.seed(0)                                      # MiniBatchKMeans takes no random_state here:
        scores = evaluator(cache, examples)                    # it falls back to NumPy's global RNG, so pin that
                                                               # or an unstructured embedding space scores 0.01-0.08
                                                               # at random. The evaluator is callable.
        BENCH.setdefault(name, {})["VMeasure"] = scores[0].value
        print(f"  {name:26s} {scores[0].metric:12s} {scores[0].value:6.3f}"
              f"   [{scores[0].min}, {scores[0].max}]  :: {scores[0].description}")
    print("\n  V-measure is the harmonic mean of homogeneity and completeness: 1.0 means the clusters")
    print("  recover the classes exactly, 0.0 means they carry no information about them. Note how much")
    print("  harsher it is on the envelope encoder than accuracy was - clustering gets no labels to lean on.")
    return ", ".join(f"{k} V={v['VMeasure']:.3f}" for k, v in BENCH.items())
clustering()

@section("6. RetrievalEvaluator: index the corpus, query it with a second take, score the ranking")
def retrieval():
    print("  Task: each query is a NOISIER RECORDING OF ONE DOCUMENT, and exactly one document is correct.")
    print("  This is identity, not category - a different question from steps 4 and 5.\n")
    out = {}
    for name, cache in CACHES.items():
        doc_ids = list(cache)
        docs = np.vstack([cache[i].embedding for i in doc_ids]).astype(np.float32)
        queries = QCACHES[name]
        searcher = retrieval_evaluator.BruteForceSearcher(candidates=docs, num_neighbors=10)
        evaluator = retrieval_evaluator.RetrievalEvaluator(searcher=searcher, id_by_index_id=doc_ids, top_k=5)
        predictions = evaluator.compute_predictions(queries)
        references = [retrieval_evaluator.RetrievalReferenceId(
            sound_id=q, reference_id=q.removesuffix("_take2")) for q in queries]
        out[name] = {s.metric: s.value for s in evaluator.compute_metrics(predictions, references)}
        q0 = next(iter(queries))
        top = [item["id"] for item in predictions[q0].items[:5]]
        print(f"  top-5 for query {q0!r} under {name}:")
        print(f"    {top}")
        print(f"    correct document at rank {top.index(q0.removesuffix('_take2')) + 1}"
              f"   |  neighbours of the same class: {sum(LABELS[i] == LABELS[q0] for i in top)}/5\n")
    metric_names = ["MRR", "EM", "RecallAt5", "NDCG@10"]
    print(f"  {'encoder':26s}" + "".join(f"{m:>14s}" for m in metric_names))
    for name, row in out.items():
        print(f"  {name:26s}" + "".join(f"{row[m]:14.3f}" for m in metric_names))
        BENCH.setdefault(name, {})["MRR"] = row["MRR"]
    print("\n  MRR is 1/rank of the correct document, EM is 'it was rank 1', RecallAt5 is 'it was in the")
    print("  top 5'. NDCG@10 here is graded credit for the same single relevant document.")
    return ", ".join(f"{k} MRR={v['MRR']:.3f}" for k, v in out.items())
retrieval()

@section("7. The metric layer on its own: WER, CER, exact match, MRR, nDCG")
def metric_layer():
    truth = "the quick brown fox jumps over the lazy dog"
    for hypothesis in [truth, "the quick brown fox jumped over a lazy dog", "quick brown fox over lazy dog"]:
        werrors, wtotal = metrics.compute_word_errors(truth, hypothesis)
        cerrors, ctotal = metrics.compute_character_errors(truth, hypothesis)
        print(f"  WER {werrors / wtotal:5.3f} ({werrors}/{wtotal} words)   "
              f"CER {cerrors / ctotal:5.3f} ({cerrors}/{ctotal} chars)   {hypothesis!r}")
    print("\n  ranking metrics take (reference, ranked_ids):")
    ranked = ["doc_b", "doc_a", "doc_c", "doc_d"]
    for reference in ["doc_b", "doc_a", "doc_c", "doc_z"]:
        rank = ranked.index(reference) + 1 if reference in ranked else None
        print(f"    reference {reference!r:8s} rank {str(rank):4s}"
              f"  EM {metrics.compute_exact_match(reference, ranked):.1f}"
              f"  MRR {metrics.compute_reciprocal_rank(reference, ranked):.3f}"
              f"  nDCG@4 {metrics.compute_ndcg_at_k(reference, ranked, k=4):.3f}")
    print("  compute_ndcg_at_k assumes ONE relevant document and compares it by equality, so pass a")
    print("  string, not a list - a list reference silently scores 0.0 while MRR still looks fine.")
    print("\n  embedding-space distances used by the reconstruction and stability tasks:")
    a = np.random.default_rng(1).standard_normal((8, 4)).astype(np.float32)
    for label, b in [("identical", a), ("noisy", a + 0.1 * np.random.default_rng(2).standard_normal(a.shape))]:
        lp = metrics.compute_lp_norm(a, b, p=2)
        dtw = metrics.compute_dynamic_time_warping_distance(a, b)
        print(f"    {label:10s} L2 {json.dumps({k: round(float(v), 3) for k, v in lp.items()})}"
              f"   DTW {json.dumps({k: round(float(v), 3) for k, v in dtw.items()})}")
    return "WER/CER, EM/MRR/nDCG, Lp and DTW distances"
metric_layer()

@section("8. SegmentationEvaluator: scoring WHAT was said and WHERE, separately")
def segmentation():
    evaluator = segmentation_evaluator.SegmentationEvaluator(tau=0.05)
    print("  Here a 'segment' carries a TERM, not a vector: SoundEmbedding.embedding holds N strings")
    print("  and timestamps holds their N [start, end] spans. tau=0.05 -> a boundary may be 50 ms out.\n")
    TERMS = [("weather", 0.00, 0.30), ("in", 0.30, 0.65), ("boston", 0.65, 1.00)]
    truth = [segmentation_evaluator.Segment(embedding=term, start_time=s, end_time=e, confidence=1.0)
             for term, s, e in TERMS]
    references = [segmentation_evaluator.SegmentationReference(example_id="utt_0", segments=truth)]
    def prediction(spans):
        return {"utt_0": types.SoundEmbedding(
            embedding=np.array([term for term, _, _ in spans]),                        # N strings
            timestamps=np.array([[s, e] for _, s, e in spans], dtype=np.float32),      # N [start, end]
            context=types.SoundContextParams(id="utt_0", sample_rate=SR, length=SR),
            scores=np.ones(len(spans), dtype=np.float32))}                             # confidences
    candidates = {
        "exact": TERMS,
        "50 ms out": [("weather", 0.00, 0.28), ("in", 0.28, 0.67), ("boston", 0.67, 1.00)],
        "right words, wrong places": [("weather", 0.00, 0.45), ("in", 0.45, 0.80), ("boston", 0.80, 1.00)],
        "right places, wrong words": [("weather", 0.00, 0.30), ("on", 0.30, 0.65), ("austin", 0.65, 1.00)],
    }
    shown = ["TimestampsAccuracy", "EmbeddingsAccuracy", "TimestampsAndEmbeddingsAccuracy", "WordErrorRate", "mAP"]
    print(f"  {'prediction':28s}" + "".join(f"{m[:13]:>15s}" for m in shown))
    for label, spans in candidates.items():
        result = evaluator.compute_scores(prediction(spans), references)   # per-example scores
        scores = {s.metric: s.value for s in evaluator.compute_metrics(result)}  # aggregated Scores
        print(f"  {label:28s}" + "".join(f"{scores[m]:15.3f}" for m in shown))
    print("\n  The last two rows are the point: one metric cannot tell 'knew the words, missed the timing'")
    print("  from 'nailed the timing, heard the wrong words'. Timestamps and embeddings are scored apart,")
    print("  and only TimestampsAndEmbeddings credits getting both right at once.")
    return "boundary + term scoring at tau=50 ms"
segmentation()

@section("9. TaskMetadata and a leaderboard that disagrees with itself")
def task_metadata():
    cache = CACHES["SpectralProfileEncoder"]
    evaluator = classification_evaluator.ClassificationEvaluator(
        class_labels=CLASSES, weights=class_prototypes(cache, LABELS), top_k_value=2)
    references = [classification_evaluator.ClassificationReference(i, LABELS[i]) for i in cache]
    scores = [s for s in evaluator.compute_metrics(evaluator.compute_predictions(cache), references)
              if s.metric in ("Accuracy", "Weighted F1-Score")]
    metadata = types.TaskMetadata(
        name="SyntheticToneClassification",
        description="Three-way classification of synthetic tones, chirps and noise",
        reference="https://github.com/google-research/mseb",
        type="Classification",
        category="sound",
        main_score="Accuracy",
        revision="1",
        dataset=types.Dataset(path="synthetic/in-notebook", revision="1"),
        scores=scores,
        eval_splits=["test"],
        eval_langs=["en_us"],
    )
    print(f"  TaskMetadata: {metadata.name}  type={metadata.type}  main_score={metadata.main_score!r}")
    print(f"                dataset={metadata.dataset.path!r} rev {metadata.dataset.revision}"
          f"  splits={metadata.eval_splits}  langs={metadata.eval_langs}")
    print(f"                scores={[f'{s.metric}={s.value:.3f}' for s in metadata.scores]}")
    try:
        types.TaskMetadata(**{**{f.name: getattr(metadata, f.name) for f in metadata.__dataclass_fields__.values()},
                              "scores": []})
    except Exception as e:
        print(f"  validated at construction: {type(e).__name__}: {e}")
    columns = ["Accuracy", "VMeasure", "MRR"]
    print(f"\n  One row per encoder, one column per task family:")
    print(f"  {'encoder':26s}" + "".join(f"{c:>12s}" for c in columns) + "     what it measures")
    for name, row in BENCH.items():
        print(f"  {name:26s}" + "".join(f"{row[c]:12.3f}" for c in columns)
              + ("     timbre -> class" if "Spectral" in name else "     loudness over time -> identity"))
    flips = [c for c in columns
             if (max(BENCH, key=lambda n: BENCH[n][c]) != max(BENCH, key=lambda n: BENCH[n]["Accuracy"]))]
    print(f"\n  The winner changes column to column ({', '.join(flips)} goes the other way). That is the whole")
    print("  argument for a MASSIVE benchmark: a single headline number would have hidden it. An encoder")
    print("  that cannot name a sound can still recognise it, and vice versa.")
    print("\n  A real submission runs mseb.runner over an mseb.task against a published dataset and writes")
    print("  these same Score objects to JSON; the layers above are exactly what it exercises.")
    return f"TaskMetadata + {len(BENCH)} encoders x {len(columns)} task families"
task_metadata()

banner("SUMMARY")
for name, res in RESULTS.items():
    print(f"  {name:<74s} {res}")
print("""
Where to go next
 - Swap in a real encoder: mseb/encoders/ ships wav2vec, Whisper, CLAP, EnCodec and SoundStream
   wrappers, plus CascadeEncoder for speech-to-text-to-embedding chains. Only the three methods
   from step 2 change; every evaluator above keeps working.
 - Run a published task: mseb.runner drives mseb.task over a real dataset with apache-beam; the
   task families live in mseb/tasks/ (classification, retrieval, reranking, transcription,
   segmentation, clustering, reasoning, brain_encoding, stability).
 - Compare against the leaderboard: https://huggingface.co/spaces/google/mseb-leaderboard
 - Read the contract you implemented: mseb/encoder.py and mseb/evaluator.py are ~500 lines total.
""")