Add Python API example for CED audio tagging. (#793)

+#!/usr/bin/env python3
+
+"""
+This script shows how to use audio tagging Python APIs to tag a file.
+
+Please read the code to download the required model files and test wave file.
+"""
+
+import logging
+import time
+from pathlib import Path
+
+import numpy as np
+import sherpa_onnx
+import soundfile as sf
+
+
+def read_test_wave():
+    # Please download the model files and test wave files from
+    # https://github.com/k2-fsa/sherpa-onnx/releases/tag/audio-tagging-models
+    test_wave = "./sherpa-onnx-ced-mini-audio-tagging-2024-04-19/test_wavs/6.wav"
+
+    if not Path(test_wave).is_file():
+        raise ValueError(
+            f"Please download {test_wave} from "
+            "https://github.com/k2-fsa/sherpa-onnx/releases/tag/audio-tagging-models"
+        )
+
+    # See https://python-soundfile.readthedocs.io/en/0.11.0/#soundfile.read
+    data, sample_rate = sf.read(
+        test_wave,
+        always_2d=True,
+        dtype="float32",
+    )
+    data = data[:, 0]  # use only the first channel
+    samples = np.ascontiguousarray(data)
+
+    # samples is a 1-d array of dtype float32
+    # sample_rate is a scalar
+    return samples, sample_rate
+
+
+def create_audio_tagger():
+    # Please download the model files and test wave files from
+    # https://github.com/k2-fsa/sherpa-onnx/releases/tag/audio-tagging-models
+    model_file = "./sherpa-onnx-ced-mini-audio-tagging-2024-04-19/model.int8.onnx"
+    label_file = (
+        "./sherpa-onnx-ced-mini-audio-tagging-2024-04-19/class_labels_indices.csv"
+    )
+
+    if not Path(model_file).is_file():
+        raise ValueError(
+            f"Please download {model_file} from "
+            "https://github.com/k2-fsa/sherpa-onnx/releases/tag/audio-tagging-models"
+        )
+
+    if not Path(label_file).is_file():
+        raise ValueError(
+            f"Please download {label_file} from "
+            "https://github.com/k2-fsa/sherpa-onnx/releases/tag/audio-tagging-models"
+        )
+
+    config = sherpa_onnx.AudioTaggingConfig(
+        model=sherpa_onnx.AudioTaggingModelConfig(
+            ced=model_file,
+            num_threads=1,
+            debug=True,
+            provider="cpu",
+        ),
+        labels=label_file,
+        top_k=5,
+    )
+    if not config.validate():
+        raise ValueError(f"Please check the config: {config}")
+
+    print(config)
+
+    return sherpa_onnx.AudioTagging(config)
+
+
+def main():
+    logging.info("Create audio tagger")
+    audio_tagger = create_audio_tagger()
+
+    logging.info("Read test wave")
+    samples, sample_rate = read_test_wave()
+
+    logging.info("Computing")
+
+    start_time = time.time()
+
+    stream = audio_tagger.create_stream()
+    stream.accept_waveform(sample_rate=sample_rate, waveform=samples)
+    result = audio_tagger.compute(stream)
+    end_time = time.time()
+
+    elapsed_seconds = end_time - start_time
+    audio_duration = len(samples) / sample_rate
+
+    real_time_factor = elapsed_seconds / audio_duration
+    logging.info(f"Elapsed seconds: {elapsed_seconds:.3f}")
+    logging.info(f"Audio duration in seconds: {audio_duration:.3f}")
+    logging.info(
+        f"RTF: {elapsed_seconds:.3f}/{audio_duration:.3f} = {real_time_factor:.3f}"
+    )
+
+    s = "\n"
+    for i, e in enumerate(result):
+        s += f"{i}: {e}\n"
+
+    logging.info(s)
+
+
+if __name__ == "__main__":
+    formatter = "%(asctime)s %(levelname)s [%(filename)s:%(lineno)d] %(message)s"
+
+    logging.basicConfig(format=formatter, level=logging.INFO)
+
+    main()

@@ -29,9 +29,9 @@ static void PybindAudioTaggingModelConfig(py::module *m) {
       .def(py::init<>())
       .def(py::init<>())
       .def(py::init<const OfflineZipformerAudioTaggingModelConfig &,
       .def(py::init<const OfflineZipformerAudioTaggingModelConfig &,
                     const std::string &, int32_t, bool, const std::string &>(),
                     const std::string &, int32_t, bool, const std::string &>(),
-           py::arg("zipformer"), py::arg("ced") = "",
-           py::arg("num_threads") = 1, py::arg("debug") = false,
-           py::arg("provider") = "cpu")
+           py::arg("zipformer") = OfflineZipformerAudioTaggingModelConfig{},
+           py::arg("ced") = "", py::arg("num_threads") = 1,
+           py::arg("debug") = false, py::arg("provider") = "cpu")
       .def_readwrite("zipformer", &PyClass::zipformer)
       .def_readwrite("zipformer", &PyClass::zipformer)
       .def_readwrite("num_threads", &PyClass::num_threads)
       .def_readwrite("num_threads", &PyClass::num_threads)
       .def_readwrite("debug", &PyClass::debug)
       .def_readwrite("debug", &PyClass::debug)