Converting a real-time MP3 audio stream to 8000/mulaw in Python

I'm working with an API that streams real-time audio in the MP3 format (44.1kHz/16bit) and I need to convert this stream to 8000/mulaw. I've tried several solutions, but all have run into issues due to the structure of the MP3 data.

My current approach is to decode and process each chunk of audio as it arrives, using PyDub and Python's audioop module. However, I often encounter errors that seem to arise from trying to decode a chunk of data that doesn't contain a complete MP3 frame.

Here's a simplified version of my current code:

from pydub import AudioSegment
import audioop
import io

class StreamConverter:
    def __init__(self):
        self.state = None  
        self.buffer = b''  

    def convert_chunk(self, chunk):
        # Add the chunk to the buffer
        self.buffer += chunk

        # Try to decode the buffer
        try:
            audio = AudioSegment.from_mp3(io.BytesIO(self.buffer))
        except CouldntDecodeError:
            return None

        # If decoding was successful, empty the buffer
        self.buffer = b''

        # Ensure audio is mono
        if audio.channels != 1:
            audio = audio.set_channels(1)

        # Get audio data as bytes
        raw_audio = audio.raw_data

        # Sample rate conversion
        chunk_8khz, self.state = audioop.ratecv(raw_audio, audio.sample_width, audio.channels, audio.frame_rate, 8000, self.state)

        # μ-law conversion
        chunk_ulaw = audioop.lin2ulaw(chunk_8khz, audio.sample_width)

        return chunk_ulaw

# This is then used as follows:
for chunk in audio_stream:
    if chunk is not None:
        ulaw_chunk = converter.convert_chunk(chunk)
        # do something with ulaw_chunk

I believe my issue stems from the fact that MP3 data is structured in frames, and I can't reliably decode the audio if a chunk doesn't contain a complete frame. Also, a frame could potentially be split between two chunks, so I can't decode them independently.

Does anyone have any ideas on how I can handle this? Is there a way to process an MP3 stream in real-time while converting to 8000/mulaw, possibly using a different library or approach?

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