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VibeVoice-ASR Server

Local speech-to-text using Microsoft's VibeVoice-ASR model. Run it as an OpenAI-compatible API server or as an MCP server that plugs directly into Claude Code, OpenCode, Cursor, and other AI tools.

  • Automatic speaker diarization

  • Timestamps on every segment

  • Output as plain text, JSON, SRT, or VTT

  • Runs on CUDA, Apple Silicon (MPS), or CPU

  • Model downloads automatically on first run

Requirements

  • Python 3.10+

  • FFmpeg (used by the model's audio processor)

Install FFmpeg:

# macOS
brew install ffmpeg

# Ubuntu / Debian
sudo apt-get install ffmpeg

# Windows (with Chocolatey)
choco install ffmpeg

Related MCP server: livechat-mcp

Quick Start

# Clone the repo
git clone https://github.com/tjameswilliams/vibevoice-server.git
cd vibevoice-server

# Create a virtual environment (recommended)
python -m venv .venv
source .venv/bin/activate  # Windows: .venv\Scripts\activate

# Install
pip install -e .

# For NVIDIA GPU acceleration (optional)
pip install -e ".[cuda]"

The first time you run either the API server or MCP server, the model (~3 GB) will be downloaded from HuggingFace and cached locally.


Option 1: OpenAI-Compatible API Server

Start the server:

vibevoice-server

The server starts on http://localhost:8000 by default. It exposes the same endpoint shape as the OpenAI Audio API, so any client library or tool that speaks that protocol works out of the box.

CLI Options

vibevoice-server [OPTIONS]

  --host        Bind address (default: 0.0.0.0)
  --port        Bind port (default: 8000)
  --device      Device: auto, cuda, mps, cpu (default: auto)
  --dtype       Data type: auto, bfloat16, float32 (default: auto)
  --log-level   Log level: debug, info, warning, error (default: info)

Transcribe Audio

curl http://localhost:8000/v1/audio/transcriptions \
  -F file=@meeting.wav \
  -F response_format=verbose_json

Parameters:

Parameter

Type

Default

Description

file

file

required

Audio file (wav, mp3, flac, m4a, ogg, etc.)

model

string

vibevoice-asr

Model identifier (accepted but ignored)

response_format

string

json

text, json, verbose_json, srt, vtt

prompt

string

Optional context to guide transcription

language

string

Language code (used in verbose_json output)

Response Formats

json (default):

{"text": "Hello, welcome to the meeting."}

verbose_json — includes timestamps, speaker IDs, and segments:

{
  "task": "transcribe",
  "language": "en",
  "duration": 12.5,
  "text": "Hello, welcome to the meeting.",
  "segments": [
    {"id": 0, "start": 0.0, "end": 3.2, "text": "Hello, welcome to the meeting.", "speaker": 0}
  ]
}

srt and vtt — subtitle formats with speaker labels, ready to use with video players.

text — plain transcript string, no JSON wrapper.

Other Endpoints

# List models
curl http://localhost:8000/v1/models

# Health check
curl http://localhost:8000/health

Using with OpenAI Client Libraries

Point any OpenAI SDK at your local server:

from openai import OpenAI

client = OpenAI(base_url="http://localhost:8000/v1", api_key="not-needed")

with open("recording.wav", "rb") as f:
    transcript = client.audio.transcriptions.create(
        model="vibevoice-asr",
        file=f,
        response_format="verbose_json",
    )

print(transcript.text)

Docker

# Build
docker build -t vibevoice-server .

# Run (CPU)
docker run -p 8000:8000 -v vibevoice-cache:/models vibevoice-server

# Run (NVIDIA GPU)
docker run --gpus all -p 8000:8000 -v vibevoice-cache:/models vibevoice-server

Option 2: MCP Server

The MCP (Model Context Protocol) server lets AI tools call transcription directly — no HTTP server needed. The model runs in the same process as the MCP server.

MCP Tools

Tool

Description

transcribe_audio

Transcribe an audio file. Pass an absolute file path and get back the transcript.

load_vibevoice_model

Pre-load the model into memory (~60-90s). Optional — the model loads automatically on first transcription.

get_vibevoice_status

Check whether the model is loaded, and which device/dtype it's using.

transcribe_audio parameters:

Parameter

Type

Default

Description

file_path

string

required

Absolute path to the audio file

response_format

string

text

text, json, verbose_json, srt, vtt

prompt

string

Optional context to guide transcription

language

string

Language code (for verbose_json output)

Claude Code

Add to your project's .mcp.json (or ~/.claude/mcp.json for global access):

{
  "mcpServers": {
    "vibevoice-asr": {
      "command": "vibevoice-mcp",
      "args": []
    }
  }
}

With device override:

{
  "mcpServers": {
    "vibevoice-asr": {
      "command": "vibevoice-mcp",
      "args": ["--device", "mps"]
    }
  }
}

Restart Claude Code after adding the config. The three tools (transcribe_audio, load_vibevoice_model, get_vibevoice_status) will appear automatically.

Cursor

Add to .cursor/mcp.json in your project root:

{
  "mcpServers": {
    "vibevoice-asr": {
      "command": "vibevoice-mcp",
      "args": []
    }
  }
}

OpenCode

Add to your OpenCode MCP configuration (opencode.json or via settings):

{
  "mcpServers": {
    "vibevoice-asr": {
      "command": "vibevoice-mcp",
      "args": []
    }
  }
}

Any MCP-Compatible Tool

The server uses stdio transport — the standard for local MCP servers. Any tool that supports MCP can run it with:

  • Command: vibevoice-mcp

  • Args: [] (optional: ["--device", "mps"] or ["--device", "cuda"])

  • Transport: stdio

The MCP server reads JSON-RPC from stdin and writes responses to stdout. All logs go to stderr.

MCP CLI Options

vibevoice-mcp [OPTIONS]

  --device      Device: auto, cuda, mps, cpu (default: auto)
  --dtype       Data type: auto, bfloat16, float32 (default: auto)
  --log-level   Log level (default: warning)

Configuration

All settings can be controlled via environment variables (prefixed with VIBEVOICE_), CLI flags, or a .env file. See .env.example for the full list.

Variable

Default

Description

VIBEVOICE_DEVICE

auto

auto, cuda, mps, cpu

VIBEVOICE_DTYPE

auto

auto, bfloat16, float32

VIBEVOICE_CACHE_DIR

(HuggingFace default)

Where to store downloaded model weights

VIBEVOICE_MODEL_ID

microsoft/VibeVoice-ASR-HF

HuggingFace model ID

VIBEVOICE_HOST

0.0.0.0

API server bind address

VIBEVOICE_PORT

8000

API server bind port

VIBEVOICE_LOG_LEVEL

info

Logging level

Device auto-detection picks the best available: CUDA > MPS > CPU.


Hardware Notes

Platform

Device

Dtype

Notes

NVIDIA GPU

cuda

bfloat16

Fastest. Flash Attention 2 enabled automatically. Install with .[cuda].

Apple Silicon

mps

float32

Works well on M1/M2/M3/M4.

CPU

cpu

float32

Slower but works everywhere.

The model is ~3 GB. First load takes 60-90 seconds (downloading + loading weights). Subsequent starts are faster when cached.


License

MIT

Available Tools

3 tools
get_vibevoice_statusA

Check the current status of the VibeVoice-ASR server.

Returns model loaded state, device, dtype, and version info.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.1/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the burden. It clearly states it is a read operation returning status. However, it does not disclose potential delays, errors, or network usage. Given the simplicity, a score of 3 is appropriate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with action and outcome. No unnecessary words. Every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given no parameters and a straightforward return (model loaded state, device, dtype, version info), the description is complete. It provides enough context for the agent to understand what the tool does and what it returns.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There are no parameters, and the schema coverage is 100% (empty). Per guidelines, 0 parameters earns a baseline of 4. The description adds no parameter info because none exist.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a clear verb 'Check' and specifies the resource 'VibeVoice-ASR server'. It lists the returned information (model loaded state, device, dtype, version info), distinguishing it from siblings like load_vibevoice_model and transcribe_audio.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit when-to-use or when-not-to-use guidance. The description implies it is a status check, but does not mention alternatives or prerequisites. For a simple status tool, minimal guidance may be acceptable.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

load_vibevoice_modelA

Pre-load the VibeVoice-ASR model into memory.

Call this before transcribing to avoid a long wait on the first transcription. Model loading takes ~60-90 seconds depending on hardware.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.4/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided, so the description carries full burden. It discloses that loading takes ~60-90 seconds and is a prerequisite for transcription. However, it does not mention if repeated calls are safe or if there are side effects.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two concise sentences, front-loaded with purpose, followed by usage guidance and timing detail. No wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description explains the tool's purpose and usage context well, but does not describe the output schema (though one exists) or mention idempotency. For a simple priming tool, this is nearly complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, so no parameter documentation is needed. The description adds no param info, but this is appropriate given the schema coverage is 100%.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'Pre-load' and the resource 'VibeVoice-ASR model', distinguishing it from sibling tools like transcribe_audio (actual transcription) and get_vibevoice_status (status checking).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly advises calling before transcribing to avoid delay, and mentions the loading time. While it lacks explicit when-not-to-use, the guidance is clear and actionable.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

transcribe_audioA

Transcribe an audio file using VibeVoice-ASR.

Args: file_path: Absolute path to the audio file (wav, mp3, flac, etc.) response_format: Output format: text, json, verbose_json, srt, vtt (default: text) prompt: Optional prompt/context to guide transcription language: Language code for verbose_json output (default: en)

ParametersJSON Schema
NameRequiredDescriptionDefault
promptNo
languageNo
file_pathYes
response_formatNotext

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A3.5/5.0
Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided, so the description must fully disclose behavior. It lacks details on side effects (read-only/mutation), file size limits, timeouts, authentication requirements, or other constraints. Only parameter descriptions exist.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured with a concise opening sentence followed by a clear 'Args' block. Minor redundancy exists (first sentence restated in file_path), but overall efficient and easy to parse.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

While the description covers parameters adequately, it omits important context: output format (though output schema exists), model loading prerequisites (implied by siblings), and potential errors. It is functional but not fully self-contained.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The description adds significant value beyond the bare input schema, which has 0% description coverage. It explains file path format and supported extensions, response format options, prompt purpose, and language usage. All four parameters are well-documented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action 'Transcribe an audio file' and names the specific tool 'VibeVoice-ASR'. It effectively distinguishes from sibling tools (get_vibevoice_status, load_vibevoice_model), which handle status and model loading.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit guidance on when to use this tool versus alternatives. The description does not mention prerequisites (e.g., model must be loaded) or when not to use it. The usage context is only implied by the action name.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. 3 tool updatesv0.1.0
    • First observedget_vibevoice_status
    • First observedload_vibevoice_model
    • First observedtranscribe_audio

TDQS

A4.1/5.0
Disambiguation5/5

Each tool has a unique purpose: checking server status, loading the model, and transcribing audio. No functional overlap, making it clear which tool to use for each task.

Naming Consistency5/5

All tool names follow a consistent verb_noun pattern in snake_case (get_vibevoice_status, load_vibevoice_model, transcribe_audio), making them predictable and easy to remember.

Tool Count5/5

Three tools cover the essential operations of an ASR server—status check, model loading, and transcription. The count is well-scoped for the domain without unnecessary extras.

Completeness4/5

The set covers the core workflow (status, load, transcribe). A minor gap is the lack of an unload model tool, but this does not severely hinder functionality for typical use cases.

Maintenance

ActivityInactive
ResponsivenessNo issues

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