Audio from older phones is too quiet coming in fro...
# ask-aif
few-soccer-7112
06/26/2025, 2:10 AMAudio from older phones is too quiet coming in from twilio, is there a way to boost audio frames before sending to STT? I'm hosting a VoicePipeline agent
t
tall-airline-16756
06/26/2025, 2:10 AMThanks for reaching out, Muthana. I'm an AI assistant and I'm here to help. Give me a moment while I research this topic.
tall-airline-16756
06/26/2025, 2:10 AMTo address the issue of quiet audio from older phones in your VoicePipeline agent, you can boost the audio frames before sending them to the Speech-to-Text (STT) service by overriding the
stt_node Copy code
from livekit import rtc
from livekit.agents import ModelSettings, stt, Agent
from typing import AsyncIterable, Optional
async def stt_node(
self, audio: AsyncIterable[rtc.AudioFrame], model_settings: ModelSettings
) -> Optional[AsyncIterable[stt.SpeechEvent]]:
async def filtered_audio():
async for frame in audio:
# insert custom audio preprocessing here
# This is where you would boost the audio
yield frame
async for event in Agent.default.stt_node(self, filtered_audio(), model_settings):
# insert custom text postprocessing here
yield eventfiltered_audio()f
few-soccer-7112
06/26/2025, 2:12 AMShow me an examle of boosting audio by a set amount
t
tall-airline-16756
06/26/2025, 2:13 AMHere is an example of how you can boost audio frames by a set amount in your VoicePipeline agent:
Copy code
class Assistant(Agent):
def __init__(self) -> None:
self.volume: int = 50 # Set your desired volume boost level (0-100%)
super().__init__(
instructions=f"You are a helpful voice AI assistant. Your starting volume level is {self.volume}."
)
async def _adjust_volume_in_stream(
self, audio: AsyncIterable[rtc.AudioFrame]
) -> AsyncIterable[rtc.AudioFrame]:
stream: utils.audio.AudioByteStream | None = None
async for frame in audio:
if stream is None:
stream = utils.audio.AudioByteStream(
sample_rate=frame.sample_rate,
num_channels=frame.num_channels,
samples_per_channel=frame.sample_rate // 10, # 100ms
)
for f in stream.push(frame.data):
yield self._adjust_volume_in_frame(f)
if stream is not None:
for f in stream.flush():
yield self._adjust_volume_in_frame(f)
def _adjust_volume_in_frame(self, frame: rtc.AudioFrame) -> rtc.AudioFrame:
audio_data = np.frombuffer(frame.data, dtype=np.int16)
audio_float = audio_data.astype(np.float32) / np.iinfo(np.int16).max
audio_float = audio_float * max(0, min(self.volume, 100)) / 100.0
processed = (audio_float * np.iinfo(np.int16).max).astype(np.int16)
return rtc.AudioFrame(
data=processed.tobytes(),
sample_rate=frame.sample_rate,
num_channels=frame.num_channels,
samples_per_channel=len(processed) // frame.num_channels,
)self.volume