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2024-06-23
2024-06-23
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import asyncio
from collections.abc import Iterable
import time
from faster_whisper import transcribe
from faster_whisper_server.audio import Audio
from faster_whisper_server.core import Transcription, Word
from faster_whisper_server.logger import logger
class FasterWhisperASR:
def __init__(
self,
whisper: transcribe.WhisperModel,
**kwargs,
) -> None:
self.whisper = whisper
self.transcribe_opts = kwargs
def _transcribe(
self,
audio: Audio,
prompt: str | None = None,
) -> tuple[Transcription, transcribe.TranscriptionInfo]:
start = time.perf_counter()
segments, transcription_info = self.whisper.transcribe(
audio.data,
initial_prompt=prompt,
word_timestamps=True,
**self.transcribe_opts,
)
words = words_from_whisper_segments(segments)
for word in words:
word.offset(audio.start)
transcription = Transcription(words)
end = time.perf_counter()
logger.info(
f"Transcribed {audio} in {end - start:.2f} seconds. Prompt: {prompt}. Transcription: {transcription.text}"
)
return (transcription, transcription_info)
async def transcribe(
self,
audio: Audio,
prompt: str | None = None,
) -> tuple[Transcription, transcribe.TranscriptionInfo]:
"""Wrapper around _transcribe so it can be used in async context."""
# is this the optimal way to execute a blocking call in an async context?
# TODO: verify performance when running inference on a CPU
return await asyncio.get_running_loop().run_in_executor(
None,
self._transcribe,
audio,
prompt,
)
def words_from_whisper_segments(segments: Iterable[transcribe.Segment]) -> list[Word]:
words: list[Word] = []
for segment in segments:
assert segment.words is not None
words.extend(
Word(
start=word.start,
end=word.end,
text=word.word,
probability=word.probability,
)
for word in segment.words
)
return words