proc-tap 0.2.0

Cross-platform process-level audio capture library

📡 ProcTap

Cross-Platform Per-Process Audio Capture

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ProcTap is a Python library for per-process audio capture with platform-specific backends.

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.

Platform Support

Platform	Status	Backend	Notes
Windows	✅ Fully Supported	WASAPI (C++ native)	Windows 10/11 (20H1+)
Linux	🧪 Experimental	PulseAudio/PipeWire	Basic support, sink monitor capture
macOS	🧪 Experimental	Core Audio Process Tap	macOS 14.4+ (Sonoma) required

_{* Linux and macOS support are experimental with limitations (see requirements). Windows is currently the only fully functional platform.}

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🚀 Features

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

• 🌍 Cross-platform architecture → Windows (fully supported) | Linux (experimental) | macOS (experimental, 14.4+)

• ⚡ Platform-optimized backends → Windows: ActivateAudioInterfaceAsync (modern WASAPI) → Linux: PulseAudio/PipeWire (experimental) → macOS: Core Audio Process Tap API (macOS 14.4+)

• 🧵 Low-latency, thread-safe audio engine → 44.1 kHz / stereo / 16-bit PCM format (Windows)

• 🐍 Python-friendly high-level API

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

• 🔌 Native extensions for high-performance → C++ extension on Windows for optimal throughput

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📦 Installation

From PyPI:

pip install proc-tap

Platform-specific dependencies are automatically installed:

• Windows: No additional dependencies
• Linux: pulsectl is automatically installed, but you also need system packages:

  # Ubuntu/Debian
  sudo apt-get install pulseaudio-utils
  
  # Fedora/RHEL
  sudo dnf install pulseaudio-utils
  

📚 Read the Full Documentation for detailed guides and API reference.

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 (Fully Supported):

• Windows 10 / 11 (20H1 or later)
• Python 3.10+
• WASAPI support
• No admin privileges required

Linux (Experimental):

• Linux with PulseAudio or PipeWire (with pulseaudio-compat)
• Python 3.10+
• pulsectl library: automatically installed with pip install proc-tap
• parec command: install with sudo apt-get install pulseaudio-utils
• ⚠️ EXPERIMENTAL: Basic PulseAudio support implemented
• ⚠️ LIMITATION: Currently captures from entire sink monitor (may include other apps)

macOS (Experimental):

• macOS 14.4 (Sonoma) or later
• Python 3.10+
• Swift CLI helper binary (proctap-macos)
• Audio capture permission
• ⚠️ EXPERIMENTAL: Core Audio Process Tap API support implemented
• ⚠️ REQUIREMENT: Requires macOS 14.4+ for Process Tap API

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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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🐧 Linux Example

from proctap import ProcessAudioTap, StreamConfig
import wave

pid = 12345  # Your target process ID

# Create WAV file
wav = wave.open("linux_capture.wav", "wb")
wav.setnchannels(2)
wav.setsampwidth(2)
wav.setframerate(44100)

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

# Create stream config (Linux backend respects these settings)
config = StreamConfig(sample_rate=44100, channels=2)

try:
    with ProcessAudioTap(pid, config=config, on_data=on_data):
        print("⚠️  Make sure the process is actively playing audio!")
        input("Recording... Press Enter to stop.\n")
finally:
    wav.close()

Linux-specific requirements:

• Install system package: sudo apt-get install pulseaudio-utils (provides parec command)
• Python dependency pulsectl is automatically installed with pip install proc-tap
• The target process must be actively playing audio
• See examples/linux_basic.py for a complete example

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🍎 macOS Example

from proctap import ProcessAudioTap, StreamConfig
import wave

pid = 12345  # Your target process ID

# Create WAV file
wav = wave.open("macos_capture.wav", "wb")
wav.setnchannels(2)
wav.setsampwidth(2)
wav.setframerate(48000)  # macOS backend default is 48 kHz

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

# Create stream config (macOS backend respects these settings)
config = StreamConfig(sample_rate=48000, channels=2)

try:
    with ProcessAudioTap(pid, config=config, on_data=on_data):
        print("⚠️  Make sure the process is actively playing audio!")
        print("⚠️  On first run, macOS will prompt for permission.")
        input("Recording... Press Enter to stop.\n")
finally:
    wav.close()

macOS-specific requirements:

• macOS 14.4 (Sonoma) or later
• Swift CLI helper binary (proctap-macos) - automatically built during installation if Swift toolchain available
• Audio capture permission - macOS will prompt on first run
• The target process must be actively playing audio
• See examples/macos_basic.py for a complete example

Building the Swift helper manually:

cd swift/proctap-macos
swift build -c release
cp .build/release/proctap-macos ../../src/proctap/bin/

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🏗 Build From Source

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

Windows Build Requirements:

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

Linux/macOS:

• No C++ compiler required (pure Python)
• Note: Backends are not yet functional on these platforms

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🤝 Contributing

Contributions are welcome! We have structured issue templates to help guide your contributions:

• 🐛 Bug Report - Report bugs or unexpected behavior
• ✨ Feature Request - Suggest new features or enhancements
• ⚡ Performance Issue - Report performance problems or optimizations
• 🔧 Type Hints / Async - Improve type annotations or async functionality
• 📚 Documentation - Improve docs, examples, or guides

Special Interest:

• PRs from WASAPI/C++ experts are especially appreciated
• Linux backend improvements (PulseAudio/PipeWire per-app isolation)
• macOS backend testing (Core Audio Process Tap on macOS 14.4+)
• Cross-platform testing and compatibility
• Performance profiling and optimization

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📄 License

MIT License

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👤 Author

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