Murf BVC for LiveKit Agents

Background voice cancellation for voice agents. Murf BVC keeps the person talking to your agent and removes everyone and everything else (TV, other people in the room, street and office noise) before your agent's VAD, turn detection and speech-to-text see the audio. Fewer false interruptions, fewer transcripts of someone else's words.

It runs on CPU inside your agent process, like LiveKit's own noise-cancellation plugin. No GPU, no network calls, no extra services.

Requirements

• Python 3.10+ and livekit-agents 1.2+
• Linux (glibc 2.28+: Ubuntu 20.04+, Debian 10+, RHEL/Rocky/Alma 8+, Amazon Linux 2023) on x86_64 or aarch64, or macOS 11+ (Apple Silicon) / 10.15+ (Intel)
• x86_64 CPUs need AVX2 and FMA (Intel Haswell / 2013 or newer, any AMD Zen); on ARM, AWS Graviton2 or newer, or any Apple Silicon Mac
• A Murf BVC license key (contact Murf)

Install

pip install livekit-plugins-murf-bvc

Quick start

1. Set your license key where the agent runs:

   export MURF_BVC_LICENSE="mbvc1...."
   

2. Pass murf_bvc.BVC() as the noise cancellation for the room's audio input:

   from livekit.agents import Agent, AgentSession, JobContext, WorkerOptions, cli, room_io
   from livekit.plugins import murf_bvc
   
   
   async def entrypoint(ctx: JobContext):
       session = AgentSession(...)  # your STT, LLM, TTS, VAD, turn detection
   
       await session.start(
           room=ctx.room,
           agent=Agent(instructions="You are a helpful assistant."),
           room_options=room_io.RoomOptions(
               audio_input=room_io.AudioInputOptions(noise_cancellation=murf_bvc.BVC()),
           ),
       )
   
   
   if __name__ == "__main__":
       cli.run_app(WorkerOptions(entrypoint_fnc=entrypoint))
   

That's all most agents need. The defaults are what we recommend for production.

Options: when to change them

murf_bvc.BVC(restore=True, normalize=True, license_key=None, native=True)

Rooms with several participants

Nothing to change: one BVC() value serves every participant, each with its own independent state.

If you use native=False (or BVCProcessor directly), each processor handles one track, so pass a selector instead:

noise_cancellation=lambda params: murf_bvc.BVC(native=False)

What to expect

• Latency: 10 ms at 16 kHz, about 13.6 ms at 24 or 48 kHz (resampling included).
• CPU: about 3% of one core per active participant on an AWS AMD EPYC instance, plus a speaker check every 0.5 s of speech while caller restore is on. Processing is single-threaded per stream, so it scales with the number of concurrent calls.
• Audio: any sample rate LiveKit delivers (8–96 kHz); stereo input is mixed to mono.

License behaviour

The license is checked offline (signature and expiry), once per process. Without a valid license BVC does not stop your agent: it logs an error and passes audio through unchanged, delayed by the same few milliseconds, so calls keep working and a license expiring mid-call never knocks audio out of sync.

Check it at startup:

murf_bvc.set_license(key)   # raises ValueError with the reason if the key is invalid
assert murf_bvc.licensed()

Troubleshooting