examples/example_qwen3_asr_transformers.py

# coding=utf-8
# Copyright 2026 The Alibaba Qwen team.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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"""
Examples for Qwen3ASRModel (Transformers backend).

Covers:
  - single-sample inference (URL audio)
  - batch inference (mixed URL / base64 / (np.ndarray, sr))
  - forcing language (text-only output)
  - returning time_stamps (single + batch) via Qwen3ForcedAligner
"""

import base64
import io
import urllib.request
from typing import Tuple

import numpy as np
import soundfile as sf
import torch

from qwen_asr import Qwen3ASRModel


ASR_MODEL_PATH = "Qwen/Qwen3-ASR-1.7B"
FORCED_ALIGNER_PATH = "Qwen/Qwen3-ForcedAligner-0.6B"

URL_ZH = "https://qianwen-res.oss-cn-beijing.aliyuncs.com/Qwen3-ASR-Repo/asr_zh.wav"
URL_EN = "https://qianwen-res.oss-cn-beijing.aliyuncs.com/Qwen3-ASR-Repo/asr_en.wav"


def _download_audio_bytes(url: str, timeout: int = 30) -> bytes:
    req = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
    with urllib.request.urlopen(req, timeout=timeout) as resp:
        return resp.read()


def _read_wav_from_bytes(audio_bytes: bytes) -> Tuple[np.ndarray, int]:
    with io.BytesIO(audio_bytes) as f:
        wav, sr = sf.read(f, dtype="float32", always_2d=False)
    return np.asarray(wav, dtype=np.float32), int(sr)


def _to_data_url_base64(audio_bytes: bytes, mime: str = "audio/wav") -> str:
    b64 = base64.b64encode(audio_bytes).decode("utf-8")
    return f"data:{mime};base64,{b64}"


def _print_result(title: str, results) -> None:
    print(f"\n===== {title} =====")
    for i, r in enumerate(results):
        print(f"[sample {i}] language={r.language!r}")
        print(f"[sample {i}] text={r.text!r}")
        if r.time_stamps is not None and len(r.time_stamps) > 0:
            head = r.time_stamps[0]
            tail = r.time_stamps[-1]
            print(f"[sample {i}] ts_first: {head.text!r} {head.start_time}->{head.end_time} s")
            print(f"[sample {i}] ts_last : {tail.text!r} {tail.start_time}->{tail.end_time} s")


def test_single_url(asr: Qwen3ASRModel) -> None:
    results = asr.transcribe(
        audio=URL_ZH,
        language=None,
        return_time_stamps=False,
    )
    assert isinstance(results, list) and len(results) == 1
    _print_result("single-url (no forced language, no timestamps)", results)


def test_batch_mixed(asr: Qwen3ASRModel) -> None:
    zh_bytes = _download_audio_bytes(URL_ZH)
    en_bytes = _download_audio_bytes(URL_EN)

    zh_b64 = _to_data_url_base64(zh_bytes, mime="audio/wav")
    en_wav, en_sr = _read_wav_from_bytes(en_bytes)

    results = asr.transcribe(
        audio=[URL_ZH, zh_b64, (en_wav, en_sr)],
        context=["", "交易 停滞", ""],
        language=[None, "Chinese", "English"],
        return_time_stamps=False,
    )
    assert len(results) == 3
    _print_result("batch-mixed (forced language for some)", results)


def test_single_with_timestamps(asr: Qwen3ASRModel) -> None:
    results = asr.transcribe(
        audio=URL_EN,
        language="English",
        return_time_stamps=True,
    )
    assert len(results) == 1
    assert results[0].time_stamps is not None
    _print_result("single-url (forced language + timestamps)", results)


def test_batch_with_timestamps(asr: Qwen3ASRModel) -> None:
    zh_bytes = _download_audio_bytes(URL_ZH)
    zh_b64 = _to_data_url_base64(zh_bytes, mime="audio/wav")

    results = asr.transcribe(
        audio=[URL_ZH, zh_b64, URL_EN],
        context=["", "交易 停滞", ""],
        language=["Chinese", "Chinese", "English"],
        return_time_stamps=True,
    )
    assert len(results) == 3
    assert all(r.time_stamps is not None for r in results)
    _print_result("batch (forced language + timestamps)", results)


def main() -> None:
    asr = Qwen3ASRModel.from_pretrained(
        ASR_MODEL_PATH,
        dtype=torch.bfloat16,
        device_map="cuda:0",
        # attn_implementation="flash_attention_2",
        forced_aligner=FORCED_ALIGNER_PATH,
        forced_aligner_kwargs=dict(
            dtype=torch.bfloat16,
            device_map="cuda:0",
            # attn_implementation="flash_attention_2",
        ),
        max_inference_batch_size=32,
        max_new_tokens=256,
    )

    test_single_url(asr)
    test_batch_mixed(asr)
    test_single_with_timestamps(asr)
    test_batch_with_timestamps(asr)


if __name__ == "__main__":
    main()