pbRecorder

A feature-rich screen recorder for Windows. Uses DXGI Desktop Duplication for high-performance capture with support for multiple codecs and container formats. Includes both GUI and CLI.

日本語版 README

What's New in 0.6.0

• Window capture no longer includes overlapping windows — Window mode now uses Windows.Graphics.Capture (WGC) instead of PrintWindow. WGC captures the target window's live composited surface at the OS level, so other windows layered on top are never recorded, and hardware-accelerated / GPU content (browsers, games, video players) that PrintWindow returned black is now captured correctly. Falls back to the previous PrintWindow path on Windows versions without WGC. Output is constant-frame-rate even for a static window.
• Per-application audio now actually works — The process-loopback capture was failing to activate on every machine: the completion handler was missing free-threaded marshaling (ActivateAudioInterfaceAsync returned E_ILLEGAL_METHOD_CALL), the client requested a format the process-loopback device rejected without AUDCLNT_STREAMFLAGS_AUTOCONVERTPCM, and for Store/UWP apps the wrong process id was targeted (ApplicationFrameHost.exe). All three are fixed, so "▶ Captured window's app audio only" records the target application's audio (and its child processes) as intended.
• Fixed a crash when starting a window recording — A non-recursive std::mutex was being re-locked on the same thread (an error path locked a mutex the caller already held), which terminated the process. Fixed across all capture/audio sources.
• Build: pbRecorder is now built with the MSVC toolchain (required for WGC/C++WinRT). The distribution bundles the Visual C++ runtime, so no separate install is needed — unzip and run as before. Requires Windows 10 1903+ (build 20348+ for per-app audio).

What's New in 0.5.8

• No more audio/video drift on long recordings — Video is now anchored to its real capture clock (the same high-resolution QPC clock the audio uses), instead of advancing by a synthetic per-frame duration. Previously the video timestamp could ratchet ahead of real time and never recover, so audio and video drifted further apart the longer you recorded. Now both streams share a single clock, so they stay in sync for the full length of the recording. Applies to all containers (MP4, WMV, MKV).

What's New in 0.5.7

• Per-application audio recording — In Window mode you can now record only the audio of the captured window's application (and its child processes) via the Windows process-loopback API. Select "▶ Captured window's app audio only" in the output device list (enabled only in Window mode).
• Accurate window capture — Fixed a slight offset when recording in Window mode. The captured content is now cropped to the window's visible (DWM) bounds, so it is no longer shifted by the invisible resize border. Window mode uses PrintWindow, so other windows overlapping the target are never captured.
• Compact, fixed-size UI — The main window was redesigned into a dense two-column dashboard (Source + Video / Audio + Output). It is non-resizable and snaps to its content (no wasted space); height grows only when a chosen codec adds rows (e.g. PCM) or the preview is shown. The capture preview is hidden by default and toggled with the Preview checkbox.

Features

Capture Modes

• Full Screen — Record entire display (multi-monitor support)
• Window — Record a specific window (via PrintWindow, so overlapping windows are never captured; cropped accurately to the window's visible bounds)
• Region — Record an arbitrary rectangular area
  • Auto-adjust — Automatically snaps to nearby window edges
  • Edges can be fine-tuned by dragging after selection
• UI Region Tracking — Select a UI Automation element under the mouse and keep the recording crop aligned to that element while it moves
  • Ctrl+Space, Enter, or click confirms the highlighted UI region; Esc cancels
  • Crop from parent window is enabled by default to reduce unrelated overlapping windows in the captured image
  • Falls back to screen cropping when the target application cannot be captured through PrintWindow

Video

• Codecs: H.264, WMV
• Hardware encoding: GPU encoding via Media Foundation
• Realtime H.264 MP4: Uses Media Foundation fragmented MP4 output to keep recording data committed during capture and reduce stop-time finalization work
• H.264 options: Profile (Baseline/Main/High), Level (Auto/4.0–5.1)
• Frame rate: Up to 240fps
• Bitrate: Configurable (default 8 Mbps)
• Mouse cursor: Toggle capture on/off

Audio

• WASAPI: System audio (loopback) or microphone input
• Per-application loopback: Record only the captured window's app audio (Window mode; uses the Windows process-loopback API, Windows 10 build 20348+ / Windows 11)
• ASIO: Optional low-latency ASIO device support (requires a separately obtained ASIO SDK)
• Codecs: AAC, MP3, Opus, Vorbis, PCM, WMA

Container Formats

• MP4 (.mp4) — H.264 + AAC/MP3
• MKV (.mkv) — H.264 + AAC/Opus/Vorbis/PCM (native implementation via libmatroska)
• WMV (.wmv) — WMV + WMA

Other

• Preset system — Save and load recording configurations
• Language switching — English / Japanese UI
• Portable — Settings stored in JSON file next to exe (no registry)
• CLI support — Full-featured command-line interface (pbRecorder-cli.exe)

System Requirements

• Windows 10 or later (64-bit)
• DirectX 11 compatible GPU
• Qt 6 runtime (included in release)

Installation

1. Download ZIP from Releases
2. Extract to any folder
3. Run pbRecorder.exe (GUI) or pbRecorder-cli.exe (CLI)

GUI Usage

1. Select capture source (Full Screen / Window / Region / UI Region Tracking)
2. Select audio devices if needed
3. Configure container format and codecs
4. Set output folder and filename
5. Click Record (or Ctrl+R) to start/stop

For UI Region Tracking, choose UI Region Tracking, click Select, hover the target pane/control, then confirm the highlighted region. Use Crop from parent window when you want to avoid unrelated overlapping windows in the capture.

Keyboard Shortcuts

• Ctrl+R — Start/stop recording from the main window
• Ctrl+Shift+R — Global start/stop hotkey
• Region selection: Enter to confirm, Esc to cancel
• UI region selection: Ctrl+Space, Enter, or click to confirm; Esc to cancel; mouse wheel / arrow keys cycle nearby parent UI regions

UI Region Tracking Notes

UI Region Tracking is available in the GUI only. It uses Windows UI Automation to identify the selected pane/control and records the corresponding rectangle. The default Crop from parent window option captures the parent window first and then crops the selected UI region, which can avoid unrelated windows covering the target. Some applications do not render correctly through PrintWindow; disable the option to record the on-screen composed pixels instead.

Limitations: UI tracking depends on the target application's UI Automation tree and window rendering behavior. Custom-rendered, elevated, hidden, or minimized applications may not expose stable UI regions. Parent-window crop may produce black or stale frames in applications that do not support PrintWindow well.

CLI Usage

pbRecorder-cli.exe provides full recording functionality from the command line. UI Region Tracking is GUI-only because it requires interactive UI element selection.

Device Enumeration

pbRecorder-cli --list-monitors
pbRecorder-cli --list-windows
pbRecorder-cli --list-audio-devices

Basic Recording

# Record full screen, stop with Ctrl+C
pbRecorder-cli --cli --auto-name -o ./Output/

# Record for 60 seconds
pbRecorder-cli --cli --duration 60 --auto-name -o ./Output/

# Specify output file
pbRecorder-cli --cli -o recording.mp4

Capture Modes

# Full screen (specific monitor)
pbRecorder-cli --cli --mode screen --monitor 1 -o out.mp4

# Window (title match)
pbRecorder-cli --cli --mode window --window "Chrome" -o out.mp4

# Region
pbRecorder-cli --cli --mode region --region 0,0,1920,1080 -o out.mp4

Video Settings

# H.264, 60fps, 12Mbps, High profile
pbRecorder-cli --cli --vcodec h264 --container mp4 --fps 60 --vbitrate 12000 \
  --profile high --level 4.1 --hw-encoder -o out.mp4

# WMV, 30fps
pbRecorder-cli --cli --vcodec wmv --fps 30 --vbitrate 5000 -o out.wmv

# MKV container
pbRecorder-cli --cli --vcodec h264 --container mkv -o out.mkv

Audio Settings

# System audio
pbRecorder-cli --cli --audio-out 0 --acodec aac --abitrate 192 -o out.mp4

# Microphone
pbRecorder-cli --cli --audio-in 0 --acodec aac --abitrate 192 -o mic.mp4

# No audio
pbRecorder-cli --cli --no-audio -o out.mp4

# MKV + Opus
pbRecorder-cli --cli --container mkv --acodec opus --abitrate 128 -o out.mkv

# MKV + PCM (96kHz/24bit)
pbRecorder-cli --cli --container mkv --acodec pcm --sample-rate 96000 --bit-depth 16 -o out.mkv

All CLI Options

Run pbRecorder-cli --help for the complete list of options.

Building from Source

Prerequisites

• CMake 3.24+
• Qt 6.9+
• MinGW-w64 or MSVC
• (Optional) ASIO SDK — obtained separately from Steinberg. It is not bundled in this repository.

Build Steps

mkdir build && cd build
cmake .. -G "MinGW Makefiles" -DCMAKE_PREFIX_PATH="<path-to-Qt6>"
cmake --build . --config Release -- -j4

To enable ASIO support, pass an SDK path outside the repository, or place a local copy under the ignored third_party/asiosdk/ directory:

cmake .. -G "MinGW Makefiles" -DCMAKE_PREFIX_PATH="<path-to-Qt6>" -DASIO_SDK_DIR="C:/SDKs/asiosdk"

If ASIO_SDK_DIR does not contain common/asio.h, pbRecorder builds without ASIO support.

This produces two executables:

• pbRecorder.exe — GUI application (WIN32 subsystem)
• pbRecorder-cli.exe — CLI application (CONSOLE subsystem)

Third-party libraries (libebml, libmatroska, libogg, libvorbis, libopus) are automatically downloaded and built via CMake FetchContent.

Smoke Tests

The project registers lightweight CTest smoke tests when BUILD_TESTING=ON:

ctest --test-dir build -C Release --output-on-failure

The tests verify CLI startup with pbRecorder-cli --help and GUI startup with pbRecorder.exe --ui-screenshot <path>. The GUI test writes an initial-window screenshot and fails if the app hangs or the image is not created.

GitHub Actions runs the same Windows build and smoke tests on pushes and pull requests.

Tech Stack

• UI: Qt 6 (Widgets)
• Capture: DXGI Desktop Duplication API
• Encoding: Media Foundation (H.264/AAC/MP3/WMV/WMA)
• MKV container: libmatroska + libebml (native implementation)
• Audio capture: WASAPI (loopback or mic), optional ASIO
• Audio codecs: libopus, libvorbis (for MKV)

Encoding & Licensing

pbRecorder uses a patent and license-clean architecture.

MP4 (H.264 + AAC/MP3)

• Encoded using Windows built-in Media Foundation
• No codec libraries are bundled — uses OS-provided H.264/AAC encoders
• No FFmpeg, x264, or other GPL/LGPL codec libraries

MKV (H.264 + AAC/Opus/Vorbis/PCM)

• Video: Media Foundation generates raw H.264 NALUs, written directly to MKV via libmatroska/libebml
• Audio: AAC uses the Windows AAC MFT directly; Opus uses libopus (BSD), Vorbis uses libvorbis (BSD)
• Container: libmatroska (LGPL) + libebml (LGPL)
• PCM (uncompressed) recording also available

WMV (WMV + WMA)

• Encoded using Media Foundation (OS built-in)

Libraries and Licenses

Library	Version	License	Purpose
Qt 6	6.9+	LGPL v3	UI framework
libmatroska	1.7.1	LGPL v2.1	MKV container writing
libebml	1.4.5	LGPL v2.1	EBML (MKV foundation)
libopus	1.4	BSD 3-Clause	Opus audio encoding
libvorbis	1.3.7	BSD 3-Clause	Vorbis audio encoding
libogg	1.3.5	BSD 3-Clause	Ogg foundation library
Media Foundation	OS built-in	Windows standard	H.264/AAC/MP3/WMV/WMA encoding
DXGI	OS built-in	Windows standard	Screen capture
WASAPI	OS built-in	Windows standard	Audio capture
Steinberg ASIO SDK	Optional, external	Steinberg license	ASIO host support; not bundled

• No GPL contamination: No GPL/AGPL libraries are used
• No FFmpeg: Codec processing does not use FFmpeg
• Vendor SDK payloads such as the Steinberg ASIO SDK are intentionally not committed to this repository

License

MIT License