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# SPDX-License-Identifier: Apache-2.0
#
# Copyright (c) 2023 Malik Talha
#
# 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
# limitations under the License.
import os
import json
import vosk
import wave
from agl_service_voiceagent.utils.common import generate_unique_uuid
class STTModel:
"""
STTModel is a class for speech-to-text (STT) recognition using the Vosk speech recognition library.
"""
def __init__(self, model_path, sample_rate=16000):
"""
Initialize the STTModel instance with the provided model and sample rate.
Args:
model_path (str): The path to the Vosk speech recognition model.
sample_rate (int, optional): The audio sample rate in Hz (default is 16000).
"""
self.sample_rate = sample_rate
self.model = vosk.Model(model_path)
self.recognizer = {}
self.chunk_size = 1024
def setup_recognizer(self):
"""
Set up a Vosk recognizer for a new session and return a unique identifier (UUID) for the session.
Returns:
str: A unique identifier (UUID) for the session.
"""
uuid = generate_unique_uuid(6)
self.recognizer[uuid] = vosk.KaldiRecognizer(self.model, self.sample_rate)
return uuid
def init_recognition(self, uuid, audio_data):
"""
Initialize the Vosk recognizer for a session with audio data.
Args:
uuid (str): The unique identifier (UUID) for the session.
audio_data (bytes): Audio data to process.
Returns:
bool: True if initialization was successful, False otherwise.
"""
return self.recognizer[uuid].AcceptWaveform(audio_data)
def recognize(self, uuid, partial=False):
"""
Recognize speech and return the result as a JSON object.
Args:
uuid (str): The unique identifier (UUID) for the session.
partial (bool, optional): If True, return partial recognition results (default is False).
Returns:
dict: A JSON object containing recognition results.
"""
self.recognizer[uuid].SetWords(True)
if partial:
result = json.loads(self.recognizer[uuid].PartialResult())
else:
result = json.loads(self.recognizer[uuid].Result())
self.recognizer[uuid].Reset()
return result
def recognize_from_file(self, uuid, filename):
"""
Recognize speech from an audio file and return the recognized text.
Args:
uuid (str): The unique identifier (UUID) for the session.
filename (str): The path to the audio file.
Returns:
str: The recognized text or error messages.
"""
if not os.path.exists(filename):
print(f"Audio file '{filename}' not found.")
return "FILE_NOT_FOUND"
wf = wave.open(filename, "rb")
if wf.getnchannels() != 1 or wf.getsampwidth() != 2 or wf.getcomptype() != "NONE":
print("Audio file must be WAV format mono PCM.")
return "FILE_FORMAT_INVALID"
# audio_data = wf.readframes(wf.getnframes())
# we need to perform chunking as target AGL system can't handle an entire audio file
audio_data = b""
while True:
chunk = wf.readframes(self.chunk_size)
if not chunk:
break # End of file reached
audio_data += chunk
if audio_data:
if self.init_recognition(uuid, audio_data):
result = self.recognize(uuid)
return result['text']
else:
result = self.recognize(uuid, partial=True)
return result['partial']
else:
print("Voice not recognized. Please speak again...")
return "VOICE_NOT_RECOGNIZED"
def cleanup_recognizer(self, uuid):
"""
Clean up and remove the Vosk recognizer for a session.
Args:
uuid (str): The unique identifier (UUID) for the session.
"""
del self.recognizer[uuid]
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