tests/collections/speechlm2/test_force_align.py

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import multiprocessing as mp
import os

import pytest
import torch
from lhotse import CutSet, Recording, SupervisionSegment
from lhotse.testing.dummies import dummy_cut, dummy_recording

from nemo.collections.speechlm2.data.force_align import ForceAligner

# Set spawn method to avoid fork+CUDA conflicts that cause ForceAligner to fall back to CPU
if mp.get_start_method(allow_none=True) != 'spawn':
    mp.set_start_method('spawn', force=True)

TEST_DATA_DIR = os.path.join(os.path.dirname(__file__), "test_data")


@pytest.fixture(scope="module")
def force_aligner():
    """Create a ForceAligner instance for testing"""
    device = 'cuda' if torch.cuda.is_available() else 'cpu'
    aligner = ForceAligner(device=device, frame_length=0.08)
    return aligner


@pytest.fixture(scope="module")
def test_cutset_from_audio_file():
    """Create a test cutset from a pre-recorded audio file."""
    audio_path = os.path.join(TEST_DATA_DIR, "force_align_test.mp3")
    text = "ten companies that let you teach english"

    rec = Recording.from_file(audio_path)
    cut = rec.to_cut()
    cut.supervisions = [
        SupervisionSegment(
            id=f"{cut.id}-0",
            recording_id=cut.recording_id,
            start=0.0,
            duration=rec.duration,
            text=text,
            speaker="user",
        ),
    ]

    return CutSet([cut])


def test_force_align_audio_file(force_aligner, test_cutset_from_audio_file):
    """Test force alignment with a pre-recorded audio file."""
    import re

    # Store original texts before alignment
    original_texts = {}
    for cut in test_cutset_from_audio_file:
        for sup in cut.supervisions:
            if sup.speaker == "user":
                original_texts[sup.id] = sup.text

    result_cuts = force_aligner.batch_force_align_user_audio(test_cutset_from_audio_file, source_sample_rate=24000)

    assert len(result_cuts) == len(test_cutset_from_audio_file)
    assert len(result_cuts) == 1

    for cut in result_cuts:
        user_supervisions = [s for s in cut.supervisions if s.speaker == "user"]
        assert len(user_supervisions) > 0

        for sup in user_supervisions:
            original_text = original_texts.get(sup.id, "")
            aligned_text = sup.text

            print(f"\n{'='*80}")
            print(f"Supervision ID: {sup.id}")
            print(f"{'='*80}")
            print(f"ORIGINAL TEXT:\n  {original_text}")
            print(f"\nALIGNED TEXT:\n  {aligned_text}")
            print(f"{'='*80}")

            if "<|" not in aligned_text:
                # TODO(kevinhu): Fix CUDA/numpy device mismatch in NeMo aligner utils
                # (get_batch_variables returns CUDA tensors that fail on .numpy() calls)
                pytest.skip("Force alignment did not produce timestamps (likely CUDA/numpy device mismatch in CI)")

            # Extract timestamp-word-timestamp patterns: <|start|> word <|end|>
            pattern = r'<\|(\d+)\|>\s+(\S+)\s+<\|(\d+)\|>'
            matches = re.findall(pattern, aligned_text)

            words_only = re.sub(r'<\|\d+\|>', '', aligned_text).split()
            words_only = [w for w in words_only if w]

            print(f"\nValidation: Found {len(matches)} timestamped words out of {len(words_only)} total words")

            assert len(matches) > 0, "Should have at least one timestamped word"
            assert len(matches) == len(
                words_only
            ), f"Every word should have timestamps. Found {len(matches)} timestamped words but {len(words_only)} total words"

            for start_frame, word, end_frame in matches:
                start_frame = int(start_frame)
                end_frame = int(end_frame)

                assert (
                    start_frame <= end_frame
                ), f"Start frame {start_frame} should be before or equal to end frame {end_frame} for word '{word}'"
                assert start_frame >= 0, f"Start frame should be non-negative for word '{word}'"
                assert end_frame >= 0, f"End frame should be non-negative for word '{word}'"


def test_force_align_no_user_supervisions(force_aligner):
    """Test with cutset containing no user supervisions"""
    cut = dummy_cut(0, recording=dummy_recording(0, with_data=True))
    cut.supervisions = [
        SupervisionSegment(
            id=cut.id,
            recording_id=cut.recording_id,
            start=0,
            duration=0.5,
            text='hello',
            speaker="assistant",
        ),
    ]
    cutset = CutSet([cut])

    result_cuts = force_aligner.batch_force_align_user_audio(cutset)

    assert len(result_cuts) == 1
    result_supervisions = list(result_cuts)[0].supervisions
    assert result_supervisions[0].text == 'hello'


def test_force_align_empty_cutset(force_aligner):
    """Test with empty cutset"""
    empty_cutset = CutSet.from_cuts([])
    result_cuts = force_aligner.batch_force_align_user_audio(empty_cutset)
    assert len(result_cuts) == 0


def test_strip_timestamps(force_aligner):
    """Test timestamp stripping utility"""
    text_with_timestamps = "<|10|> hello <|20|> world <|30|>"
    result = force_aligner._strip_timestamps(text_with_timestamps)
    assert result == "hello world"
    assert "<|" not in result

    text_without_timestamps = "hello world"
    result = force_aligner._strip_timestamps(text_without_timestamps)
    assert result == "hello world"


def test_normalize_transcript(force_aligner):
    """Test transcript normalization"""
    assert force_aligner._normalize_transcript("Hello World!") == "hello world"
    assert force_aligner._normalize_transcript("don't worry") == "don't worry"
    assert force_aligner._normalize_transcript("test123") == "test"
    assert force_aligner._normalize_transcript("A,B.C!D?E") == "a b c d e"