util.py

from typing import Iterator, TextIO


def format_timestamp(seconds: float, always_include_hours: bool = False, decimal_marker: str = '.') -> 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_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 bucket_cdn_url(bucket_name: str, region: str = 'ams3') -> str:
    return f"https://{bucket_name}.{region}.cdn.digitaloceanspaces.com"


def coalesce_short_transcript_segments(segments: list,) -> list:
    """
    Some extracted transcript segments from openai/whisper are really short, like even just one word.
    This function accepts a minimum segment length and combines short segments until the minimum is reached.
    """
    minimum_transcript_len = 100  # About 1 sentence
    previous = None
    long_enough_segments = []
    for current in segments:
        if previous is None:
            previous = current
        elif len(previous["text"]) < minimum_transcript_len:
            previous = _merge_segments(left=previous, right=current)
        else:
            long_enough_segments.append(previous)
            previous = current
    if previous:
        long_enough_segments.append(previous)
    return long_enough_segments


def _merge_segments(left, right):
    return {
        "text": left["text"] + " " + right["text"],
        "start": left["start"],
        "end": right["end"],
    }