proc-tap 0.1.0

Process-level audio tap for Windows

📡 ProcTap

Per-Process Audio Capture for Windows

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ProcTap is a Python library with a high-performance C++ backend that enables per-process audio capture on Windows 10/11 (20H1+) using ActivateAudioInterfaceAsync.

Capture audio from a specific process only — without system sounds or other app audio mixed in. Ideal for VRChat, games, DAWs, browsers, and AI audio analysis pipelines.

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🚀 Features

• 🎧 Capture audio from a single target process
  (VRChat, games, browsers, Discord, DAWs, streaming tools, etc.)

• ⚡ Uses ActivateAudioInterfaceAsync (modern WASAPI)
  → More stable than legacy IAudioClient2 loopback approaches

• 🧵 Low-latency, thread-safe C++ engine → 44.1 kHz / stereo / 16-bit PCM format

• 🐍 Python-friendly high-level API

  • Callback-based streaming
  • Async generator streaming (async for)

• 🔌 Native extension for high-throughput PCM delivery

• 🪟 Windows-only (10/11, 20H1+)

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📦 Installation

From PyPI (coming soon):

pip install proctap

From TestPyPI (for testing pre-releases):

pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ proctap

From Source:

git clone https://github.com/m96-chan/ProcTap
cd ProcTap
pip install -e .

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🛠 Requirements

• Windows 10 / 11 (20H1 or later recommended)
• Python 3.10+
• WASAPI support
• No admin privileges required
  (Per-process loopback capture works with standard user permissions)

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🧰 Basic Usage (Callback API)

from proctap import ProcTap, StreamConfig

def on_chunk(pcm: bytes, frames: int):
    print(f"Received {len(pcm)} bytes ({frames} frames)")

pid = 12345  # Target process ID

tap = ProcTap(pid, StreamConfig(), on_data=on_chunk)
tap.start()

input("Recording... Press Enter to stop.\n")

tap.close()

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🔁 Async Usage (Async Generator)

import asyncio
from proctap import ProcTap

async def main():
    tap = ProcTap(pid=12345)
    tap.start()

    async for chunk in tap.iter_chunks():
        print(f"PCM chunk size: {len(chunk)} bytes")

asyncio.run(main())

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📄 API Overview

class ProcTap

Control Methods:

Method	Description
start()	Start WASAPI per-process capture
stop()	Stop capture
close()	Release native resources

Data Access:

Method	Description
iter_chunks()	Async generator yielding PCM chunks
read(timeout=1.0)	Synchronous: read one chunk (blocking)

Properties:

Property	Type	Description
is_running	bool	Check if capture is active
pid	int	Get target process ID
config	StreamConfig	Get stream configuration

Utility Methods:

Method	Description
set_callback(callback)	Change or remove audio callback
get_format()	Get audio format info (dict)

Audio Format

Note: The native extension uses a fixed audio format (hardcoded in C++):

Parameter	Value	Description
Sample Rate	44,100 Hz	CD quality (fixed)
Channels	2	Stereo (fixed)
Bit Depth	16-bit	PCM format (fixed)

The StreamConfig class exists for API compatibility but does not change the native backend format.

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🎯 Use Cases

• 🎮 Record audio from one game only
• 🕶 Capture VRChat audio cleanly (without system sounds)
• 🎙 Feed high-SNR audio into AI recognition models
• 📹 Alternative to OBS "Application Audio Capture"
• 🎧 Capture DAW/app playback for analysis tools

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📚 Example: Save to WAV

from proctap import ProcTap
import wave

pid = 12345

wav = wave.open("output.wav", "wb")
wav.setnchannels(2)
wav.setsampwidth(2)  # 16-bit PCM
wav.setframerate(44100)  # Native format is 44.1 kHz

def on_data(pcm, frames):
    wav.writeframes(pcm)

with ProcTap(pid, on_data=on_data):
    input("Recording... Press Enter to stop.\n")

wav.close()

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📚 Example: Synchronous Read API

from proctap import ProcTap

tap = ProcTap(pid=12345)
tap.start()

try:
    while True:
        chunk = tap.read(timeout=1.0)  # Blocking read
        if chunk:
            print(f"Got {len(chunk)} bytes")
            # Process audio data...
        else:
            print("Timeout, no data")
except KeyboardInterrupt:
    pass
finally:
    tap.close()

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🏗 Build From Source

git clone https://github.com/m96-chan/ProcTap
cd ProcTap
pip install -e .

Requirements:

• Visual Studio Build Tools
• Windows SDK
• CMake (if you modularize the C++ code)

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🔧 Project Structure

ProcTap/
├─ LICENSE
├─ README.md
├─ pyproject.toml
├─ setup.cfg
├─ setup.py
├─ src/
│  └─ proctap/
│     ├─ __init__.py
│     ├─ core.py
│     ├─ _native.cpp
│     └─ _native.pyi
├─ examples/
│  └─ record_proc_to_wav.py
└─ .github/
   └─ workflows/
      └─ build-wheels.yml

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🛠 GitHub Action (Wheel Build)

name: Build and publish wheels

on:
  push:
    tags:
      - "v*.*.*"
  workflow_dispatch: {}

jobs:
  build-wheels:
    runs-on: windows-latest

    strategy:
      matrix:
        python-version: ["3.10", "3.11", "3.12", "3.13"]

    steps:
      - uses: actions/checkout@v4

      - name: Setup Python
        uses: actions/setup-python@v5
        with:
          python-version: ${{ matrix.python-version }}

      - name: Install build tools
        run: |
          pip install --upgrade pip
          pip install build

      - name: Build wheel
        run: |
          python -m build --wheel

      - name: Upload artifact
        uses: actions/upload-artifact@v4
        with:
          name: wheels-py${{ matrix.python-version }}
          path: dist/*.whl

  publish:
    needs: build-wheels
    runs-on: ubuntu-latest
    if: startsWith(github.ref, 'refs/tags/v')
    steps:
      - uses: actions/download-artifact@v4
        with:
          path: dist

      - name: Flatten wheels
        shell: bash
        run: |
          mkdir -p upload
          find dist -name '*.whl' -exec cp {} upload/ \;

      - name: Publish to PyPI
        uses: pypa/gh-action-pypi-publish@v1.12.4
        with:
          user: __token__
          password: ${{ secrets.PYPI_API_TOKEN }}
          packages_dir: upload

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🤝 Contributing

Contributions are welcome!

• Bug fixes
• Feature requests
• Performance improvements
• Type hints / async extension
• Documentation improvements

PRs from WASAPI/C++ experts are especially appreciated.

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📄 License

MIT License

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👤 Author

Yusuke Harada (m96-chan)
Windows Audio / VRChat Tools / Python / C++
https://github.com/m96-chan