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2026-07-13 13:39:38 +08:00

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Python

# Copyright 2023 LiveKit, Inc.
#
# 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.
from __future__ import annotations
import asyncio
import base64
import json
from dataclasses import dataclass, replace
from typing import Literal
import httpx
import openai
from livekit.agents import (
APIConnectionError,
APIConnectOptions,
APIStatusError,
APITimeoutError,
tts,
)
from livekit.agents.types import DEFAULT_API_CONNECT_OPTIONS, NOT_GIVEN, NotGivenOr
from livekit.agents.utils import aio, is_given
from .models import TTSModels, TTSVoices
from .utils import AsyncAzureADTokenProvider
SAMPLE_RATE = 24000
NUM_CHANNELS = 1
DEFAULT_MODEL = "gpt-4o-mini-tts"
DEFAULT_VOICE = "ash"
RESPONSE_FORMATS = Literal["mp3", "opus", "aac", "flac", "wav", "pcm"] | str
# Models that use audio stream format (character-based billing)
AUDIO_STREAM_MODELS = {"tts-1", "tts-1-hd"}
@dataclass
class _TTSOptions:
model: TTSModels | str
voice: TTSVoices | str
speed: float
instructions: str | None
response_format: RESPONSE_FORMATS
class TTS(tts.TTS):
def __init__(
self,
*,
model: TTSModels | str = DEFAULT_MODEL,
voice: TTSVoices | str = DEFAULT_VOICE,
speed: float = 1.0,
instructions: NotGivenOr[str] = NOT_GIVEN,
base_url: NotGivenOr[str] = NOT_GIVEN,
api_key: NotGivenOr[str] = NOT_GIVEN,
client: openai.AsyncClient | None = None,
response_format: NotGivenOr[RESPONSE_FORMATS] = NOT_GIVEN,
) -> None:
"""
Create a new instance of OpenAI TTS.
``api_key`` must be set to your OpenAI API key, either using the argument or by setting the
``OPENAI_API_KEY`` environmental variable.
"""
super().__init__(
capabilities=tts.TTSCapabilities(streaming=False),
sample_rate=SAMPLE_RATE,
num_channels=NUM_CHANNELS,
)
self._opts = _TTSOptions(
model=model,
voice=voice,
speed=speed,
instructions=instructions if is_given(instructions) else None,
response_format=response_format if is_given(response_format) else "mp3",
)
if is_given(api_key) and not api_key:
raise ValueError(
"OpenAI API key is required, either as argument or set"
" OPENAI_API_KEY environment variable"
)
self._owns_client = client is None
self._client = client or openai.AsyncClient(
max_retries=0,
api_key=api_key if is_given(api_key) else None,
base_url=base_url if is_given(base_url) else None,
http_client=httpx.AsyncClient(
timeout=httpx.Timeout(connect=15.0, read=5.0, write=5.0, pool=5.0),
follow_redirects=True,
limits=httpx.Limits(
max_connections=50, max_keepalive_connections=50, keepalive_expiry=120
),
),
)
self._prewarm_task: asyncio.Task | None = None
@property
def model(self) -> str:
return self._opts.model
@property
def provider(self) -> str:
return self._client._base_url.netloc.decode("utf-8")
def update_options(
self,
*,
model: NotGivenOr[TTSModels | str] = NOT_GIVEN,
voice: NotGivenOr[TTSVoices | str] = NOT_GIVEN,
speed: NotGivenOr[float] = NOT_GIVEN,
instructions: NotGivenOr[str] = NOT_GIVEN,
) -> None:
if is_given(model):
self._opts.model = model
if is_given(voice):
self._opts.voice = voice
if is_given(speed):
self._opts.speed = speed
if is_given(instructions):
self._opts.instructions = instructions
@staticmethod
def with_azure(
*,
model: TTSModels | str = DEFAULT_MODEL,
voice: TTSVoices | str = DEFAULT_VOICE,
speed: float = 1.0,
instructions: NotGivenOr[str] = NOT_GIVEN,
azure_endpoint: str | None = None,
azure_deployment: str | None = None,
api_version: str | None = None,
api_key: str | None = None,
azure_ad_token: str | None = None,
azure_ad_token_provider: AsyncAzureADTokenProvider | None = None,
organization: str | None = None,
project: str | None = None,
base_url: str | None = None,
response_format: NotGivenOr[RESPONSE_FORMATS] = NOT_GIVEN,
timeout: httpx.Timeout | None = None,
) -> TTS:
"""
Create a new instance of Azure OpenAI TTS.
This automatically infers the following arguments from their corresponding environment
variables if they are not provided:
- `api_key` from `AZURE_OPENAI_API_KEY`
- `organization` from `OPENAI_ORG_ID`
- `project` from `OPENAI_PROJECT_ID`
- `azure_ad_token` from `AZURE_OPENAI_AD_TOKEN`
- `api_version` from `OPENAI_API_VERSION`
- `azure_endpoint` from `AZURE_OPENAI_ENDPOINT`
"""
azure_client = openai.AsyncAzureOpenAI(
max_retries=0,
azure_endpoint=azure_endpoint,
azure_deployment=azure_deployment,
api_version=api_version,
api_key=api_key,
azure_ad_token=azure_ad_token,
azure_ad_token_provider=azure_ad_token_provider,
organization=organization,
project=project,
base_url=base_url,
timeout=timeout
if timeout
else httpx.Timeout(connect=15.0, read=5.0, write=5.0, pool=5.0),
) # type: ignore
tts = TTS(
model=model,
voice=voice,
speed=speed,
instructions=instructions,
client=azure_client,
response_format=response_format,
)
tts._owns_client = True
return tts
def synthesize(
self, text: str, *, conn_options: APIConnectOptions = DEFAULT_API_CONNECT_OPTIONS
) -> tts.ChunkedStream:
# Use audio stream format for tts-1/tts-1-hd (character-based billing)
# Use SSE stream format for newer models like gpt-4o-mini-tts (token-based billing)
if self._opts.model in AUDIO_STREAM_MODELS:
return AudioChunkedStream(tts=self, input_text=text, conn_options=conn_options)
return SSEChunkedStream(tts=self, input_text=text, conn_options=conn_options)
def prewarm(self) -> None:
async def _prewarm() -> None:
try:
await self._client.get("/", cast_to=str)
except Exception:
pass
self._prewarm_task = asyncio.create_task(_prewarm())
async def aclose(self) -> None:
if self._prewarm_task:
await aio.cancel_and_wait(self._prewarm_task)
if self._owns_client:
await self._client.close()
class AudioChunkedStream(tts.ChunkedStream):
"""ChunkedStream for tts-1 and tts-1-hd models using audio stream format."""
def __init__(self, *, tts: TTS, input_text: str, conn_options: APIConnectOptions) -> None:
super().__init__(tts=tts, input_text=input_text, conn_options=conn_options)
self._tts: TTS = tts
self._opts = replace(tts._opts)
async def _run(self, output_emitter: tts.AudioEmitter) -> None:
oai_stream = self._tts._client.audio.speech.with_streaming_response.create(
input=self.input_text,
model=self._opts.model,
voice=self._opts.voice,
response_format=self._opts.response_format, # type: ignore
speed=self._opts.speed,
instructions=self._opts.instructions or openai.omit,
stream_format="audio",
timeout=httpx.Timeout(30, connect=self._conn_options.timeout),
)
try:
async with oai_stream as stream:
output_emitter.initialize(
request_id=stream.request_id or "",
sample_rate=SAMPLE_RATE,
num_channels=NUM_CHANNELS,
mime_type=f"audio/{self._opts.response_format}",
)
async for data in stream.iter_bytes():
output_emitter.push(data)
output_emitter.flush()
except openai.APITimeoutError:
raise APITimeoutError() from None
except openai.APIStatusError as e:
raise APIStatusError(
e.message, status_code=e.status_code, request_id=e.request_id, body=e.body
) from None
except Exception as e:
raise APIConnectionError() from e
class SSEChunkedStream(tts.ChunkedStream):
"""ChunkedStream for gpt-4o-mini-tts and newer models using SSE stream format."""
def __init__(self, *, tts: TTS, input_text: str, conn_options: APIConnectOptions) -> None:
super().__init__(tts=tts, input_text=input_text, conn_options=conn_options)
self._tts: TTS = tts
self._opts = replace(tts._opts)
async def _run(self, output_emitter: tts.AudioEmitter) -> None:
oai_stream = self._tts._client.audio.speech.with_streaming_response.create(
input=self.input_text,
model=self._opts.model,
voice=self._opts.voice,
response_format=self._opts.response_format, # type: ignore
speed=self._opts.speed,
instructions=self._opts.instructions or openai.omit,
stream_format="sse",
timeout=httpx.Timeout(30, connect=self._conn_options.timeout),
)
try:
async with oai_stream as stream:
output_emitter.initialize(
request_id=stream.request_id or "",
sample_rate=SAMPLE_RATE,
num_channels=NUM_CHANNELS,
mime_type=f"audio/{self._opts.response_format}",
)
# Parse SSE events from the stream
async for line in stream.iter_lines():
if not line or not line.startswith("data: "):
continue
data = line[6:] # Remove "data: " prefix
if data == "[DONE]":
break
try:
event = json.loads(data)
except json.JSONDecodeError:
continue
event_type = event.get("type", "")
if event_type == "speech.audio.delta":
# Decode base64 audio and push to emitter
audio_b64 = event.get("delta", "") or event.get("audio", "")
if audio_b64:
audio_data = base64.b64decode(audio_b64)
output_emitter.push(audio_data)
elif event_type == "speech.audio.done":
# Extract token usage from the done event
usage = event.get("usage", {})
input_tokens = usage.get("input_tokens", 0)
output_tokens = usage.get("output_tokens", 0)
if input_tokens or output_tokens:
self._set_token_usage(
input_tokens=input_tokens,
output_tokens=output_tokens,
)
output_emitter.flush()
except openai.APITimeoutError:
raise APITimeoutError() from None
except openai.APIStatusError as e:
raise APIStatusError(
e.message, status_code=e.status_code, request_id=e.request_id, body=e.body
) from None
except Exception as e:
raise APIConnectionError() from e