modules/whisper_extractor/utils.py

# Copyright (c) 2023 Amphion.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.

# This module is modified from [Whisper](https://github.com/openai/whisper.git).

# ## Citations

# ```bibtex
# @inproceedings{openai-whisper,
#   author       = {Alec Radford and
#                   Jong Wook Kim and
#                   Tao Xu and
#                   Greg Brockman and
#                   Christine McLeavey and
#                   Ilya Sutskever},
#   title        = {Robust Speech Recognition via Large-Scale Weak Supervision},
#   booktitle    = {{ICML}},
#   series       = {Proceedings of Machine Learning Research},
#   volume       = {202},
#   pages        = {28492--28518},
#   publisher    = {{PMLR}},
#   year         = {2023}
# }
# ```
#

import zlib
from typing import Iterator, TextIO


def exact_div(x, y):
    assert x % y == 0
    return x // y


def str2bool(string):
    str2val = {"True": True, "False": False}
    if string in str2val:
        return str2val[string]
    else:
        raise ValueError(f"Expected one of {set(str2val.keys())}, got {string}")


def optional_int(string):
    return None if string == "None" else int(string)


def optional_float(string):
    return None if string == "None" else float(string)


def compression_ratio(text) -> float:
    text_bytes = text.encode("utf-8")
    return len(text_bytes) / len(zlib.compress(text_bytes))


def format_timestamp(
    seconds: float, always_include_hours: bool = False, decimal_marker: str = "."
):
    assert seconds >= 0, "non-negative timestamp expected"
    milliseconds = round(seconds * 1000.0)

    hours = milliseconds // 3_600_000
    milliseconds -= hours * 3_600_000

    minutes = milliseconds // 60_000
    milliseconds -= minutes * 60_000

    seconds = milliseconds // 1_000
    milliseconds -= seconds * 1_000

    hours_marker = f"{hours:02d}:" if always_include_hours or hours > 0 else ""
    return (
        f"{hours_marker}{minutes:02d}:{seconds:02d}{decimal_marker}{milliseconds:03d}"
    )


def write_txt(transcript: Iterator[dict], file: TextIO):
    for segment in transcript:
        print(segment["text"].strip(), file=file, flush=True)


def write_vtt(transcript: Iterator[dict], file: TextIO):
    print("WEBVTT\n", file=file)
    for segment in transcript:
        print(
            f"{format_timestamp(segment['start'])} --> {format_timestamp(segment['end'])}\n"
            f"{segment['text'].strip().replace('-->', '->')}\n",
            file=file,
            flush=True,
        )


def write_srt(transcript: Iterator[dict], file: TextIO):
    """
    Write a transcript to a file in SRT format.

    Example usage:
        from pathlib import Path
        from whisper.utils import write_srt

        result = transcribe(model, audio_path, temperature=temperature, **args)

        # save SRT
        audio_basename = Path(audio_path).stem
        with open(Path(output_dir) / (audio_basename + ".srt"), "w", encoding="utf-8") as srt:
            write_srt(result["segments"], file=srt)
    """
    for i, segment in enumerate(transcript, start=1):
        # write srt lines
        print(
            f"{i}\n"
            f"{format_timestamp(segment['start'], always_include_hours=True, decimal_marker=',')} --> "
            f"{format_timestamp(segment['end'], always_include_hours=True, decimal_marker=',')}\n"
            f"{segment['text'].strip().replace('-->', '->')}\n",
            file=file,
            flush=True,
        )