Save what just happened.
Lightweight, open-source instant replay for Windows — built to stay recording.

Download Captail · Report a problem

Captail is a focused alternative to NVIDIA ShadowPlay Instant Replay. It keeps the latest seconds or minutes in a rolling buffer, then saves them when you press a hotkey. No scenes, streaming setup, account, cloud upload, analytics, or telemetry.

Warning

Captail v0.1.x is an early public preview. Recording works, but bugs and hardware-specific problems are expected. NVIDIA RTX 40 and RTX 50 series are tested; other GPUs need broader public testing.

Is Captail for me?

Captail is for Windows players who want instant replay without running a full streaming suite or wondering whether recording silently stopped.

It is a good fit if you want:

• one hotkey to save recent gameplay;
• desktop capture that automatically switches to a fullscreen game;
• a game-only mode that never records the desktop;
• real high-frame-rate capture for slow motion;
• system/game and microphone audio, mixed or separated;
• automatic recovery after recoverable capture, game, or driver failures;
• local files that stay on your PC.

Captail is not a streaming application, scene compositor, DRM bypass, or cloud clip service.

What does it look like?

How do I install it?

Open GitHub Releases and choose one package:

Package	Choose it when	Installation
Captail-x.y.z-Setup-win-x64.exe	You want the normal Windows experience	Run Setup. It installs Captail for your Windows account and adds an uninstaller to Windows Settings.
Captail-x.y.z-Portable-win-x64.zip	You want a movable, self-contained folder	Extract the entire ZIP, then run Captail.exe inside it. Do not run it from the archive.
SHA256SUMS.txt	You want to verify the download	Compare the package SHA-256 with the published value before running it.

Both packages include .NET, libobs, and FFmpeg. You do not need to install OBS Studio or extra runtimes.

Note

Release binaries are not Authenticode-signed yet. Windows SmartScreen may show “Unknown publisher.” Verify SHA256SUMS.txt and GitHub build provenance if you want to confirm the download.

Important

Already using Captail 0.1.3 or 0.1.4? Their updater contains a Windows file-lock bug. Download and run the 0.1.5 Setup EXE manually once. In-app updates work normally starting with 0.1.5.

How do I save my first replay?

1. Launch Captail. It stays available from the system tray.
2. Open Settings and choose Desktop or Game Capture.
3. Choose buffer length, codec, resolution, FPS, and audio sources.
4. Leave Instant Replay enabled.
5. Play normally.
6. Press Ctrl+Shift+F10, or click Save, when something worth keeping happens.

Default hotkeys:

Action	Default
Save recent footage	Ctrl+Shift+F10
Enable or disable Instant Replay	Ctrl+Shift+F9

Both hotkeys are configurable. Double-click the tray icon to reopen Captail.

What does each capture mode record?

Mode	When no game is detected	When a fullscreen game appears	Audio source
Desktop	Records the selected monitor	Automatically switches to direct Game Capture	Selected Windows output device
Game Capture	Waits without recording the desktop	Captures the detected game directly	Detected game audio

The replay buffer stays armed in both modes. Use Desktop when you want continuous coverage; use Game Capture when privacy outside games matters more.

What happens when capture breaks?

Captail supervises the recording pipeline instead of assuming that a successful start means it will remain healthy forever.

Situation	Expected behavior
Game closes or crashes	Desktop mode returns to desktop capture. Game Capture mode waits for another game.
You switch between game and desktop	Desktop mode follows the active capture source without stopping the buffer.
A capture source temporarily disappears	Captail keeps the pipeline supervised and retries recovery.
Graphics driver restarts	Video may pause or go black temporarily; the watchdog attempts a controlled restart with retry delay.
Recovery cannot complete	Captail reports the failure and retries instead of silently claiming that replay is active.
DRM-protected video appears	Protected regions may be black. Captail does not bypass DRM and is designed to keep the buffer running.

Recovery reduces lost footage; it cannot guarantee frames that Windows, a game, an anti-cheat system, or a failed driver never delivered.

Where is the rolling buffer stored?

The live replay buffer stores compressed video and audio packets in RAM. Only saved replays are written to your selected folder.

• Buffer length controls how much recent time Captail tries to keep.
• Buffer limit caps compressed replay data in RAM. If it is reached first, available replay time becomes shorter.
• Bitrate, resolution, FPS, and codec affect both memory use and saved file size.
• The dashboard shows free space on the drive containing your replay folder.

After a successful save, Captail starts a new replay segment. Saving again five minutes later produces roughly five minutes of new footage instead of duplicating the previous clip.

Which codec should I choose?

Captail detects the current GPU and driver, then hides unavailable hardware codecs.

Codec	Best for	Trade-off
AV1	Best compression on supported modern GPUs	Newest format; some older players and editors may not support it. Hardware support commonly includes GeForce RTX 40/50, Radeon RX 7000, and Intel Arc.
HEVC / H.265	Good compression with broader modern-GPU support	Compatibility is better than AV1 but still weaker than H.264 in older software.
H.264 / AVC	Easiest playback, editing, and sharing	Larger files or lower quality at the same bitrate.

Unsure? Start with H.264 for compatibility. Use AV1 when your GPU and editor support it and file efficiency matters.

Does 240 FPS mean 240 real frames?

Captail requests real frames from the capture source; it does not generate duplicates to make a file report a higher FPS.

• Game Capture: can record distinct high-rate frames when the game, GPU, encoder, and capture path can sustain them.
• Desktop capture: limited by how often Windows and the monitor present new desktop frames.
• Slow motion: 120–240 FPS is useful only when the source actually produces that many distinct frames.

Higher FPS raises GPU load, RAM use, and file size. Captail supports 30, 60, 120, 144, and 240 FPS.

How does audio work?

You can record system or detected-game audio, a microphone, or both.

• Change system and microphone volume independently.
• Add up to +20 dB microphone boost when 100% is still too quiet.
• Use One mixed track for maximum player compatibility.
• Use Separate tracks to keep system/game audio and microphone independent for editing.
• Choose AAC in fragmented MP4 or Opus in MKV.

Some media players play only one track from a multi-track file. Captail's clip editor previews the available tracks together and lets you keep or remove each track from the trimmed result.

Can I manage and trim replays inside Captail?

Yes. The main window lists supported files from the selected replay folder in a scrollable library.

• Open a replay in File Explorer.
• Move it to the Recycle Bin after confirmation.
• Scrub through a responsive preview.
• Select one trim range with draggable handles.
• Keep or remove each audio track.
• Save a new copy or overwrite the original after confirmation.
• See estimated output size, original size, resolution, source FPS, and codec.

Trimming uses stream copy when possible, avoiding a full video re-encode.

Can Captail organize clips by game?

Enable Organize games into folders in Storage. Replays saved while a game is detected go into a folder named after that game's executable. Replays saved while Desktop remains active stay in the main replay folder.

Does Captail send or upload my recordings?

No. Captail has no account, cloud upload, analytics, or telemetry. Replays, thumbnails, settings, and logs stay on your PC.

Captail contacts the GitHub Releases API to check whether a newer version exists. It downloads an update package only after you click the update control.

How is Captail different from ShadowPlay and OBS Replay Buffer?

	Captail	ShadowPlay	OBS Replay Buffer
Primary job	Instant replay	NVIDIA capture suite	Recording/streaming production
GPU support goal	NVIDIA, AMD, Intel hardware encoders	NVIDIA	Broad through OBS
Setup	Choose settings and leave it in tray	GeForce/NVIDIA App	Configure scenes, sources, and output
Automatic desktop/game switching	Yes, in Desktop mode	Platform-managed	Requires scene/source setup
Capture watchdog and recovery	Built around automatic supervision	Internal behavior	Not Captail's focused workflow
Built-in replay library and trim editor	Yes	Varies by NVIDIA software version	No focused clip library
Open source	Yes	No	Yes

Captail uses libobs for capture and encoding, but it is not an OBS Studio frontend. It exposes no streaming, scenes, transitions, or plugin management because those features would work against its small, single-purpose UI.

Will it work on my PC?

Requirements:

• Windows 10 version 2004 or newer, or Windows 11;
• x64 processor and operating system;
• a GPU and driver exposing a supported hardware H.264, HEVC, or AV1 encoder.

Current hardware status:

Hardware	Status
NVIDIA GeForce RTX 50 series	Tested
NVIDIA GeForce RTX 40 series	Tested
Older NVIDIA GPUs	Not yet verified; expected to work when supported by libobs/NVENC
AMD GPUs	Capability detection implemented; public hardware testing needed
Intel GPUs	Capability detection implemented; public hardware testing needed

Codec options are based on detected encoder support. Captail falls back to another available codec if a previously selected encoder disappears.

What are the current limitations?

• This is an early preview; hardware-specific bugs are expected.
• Release binaries are not Authenticode-signed.
• Some games or anti-cheat configurations may block Game Capture.
• DRM-protected regions cannot be recorded and may appear black.
• Desktop capture cannot create unique frames beyond the desktop presentation rate.
• Older NVIDIA, AMD, and Intel hardware needs more real-world testing.

What information should I include in a bug report?

First check existing issues, then open the bug report form.

Include:

• Captail version and Setup/Portable package type;
• Windows version;
• GPU model and graphics-driver version;
• capture mode, codec, resolution, FPS, and audio configuration;
• exact reproduction steps and expected/actual behavior;
• %LOCALAPPDATA%\Captail\log.txt, when relevant.

Review logs before attaching them and remove personal paths or other sensitive information. Report security vulnerabilities privately through the process in SECURITY.md.

Compatibility reports for older NVIDIA, AMD, and Intel GPUs are useful even when everything works.

How do I build or contribute?

Development requires Windows 10/11 x64, .NET 9 SDK, CMake 3.20+, and Visual Studio 2022 Build Tools with Desktop development with C++.

git clone https://github.com/FaulMit/captail.git
cd captail
dotnet restore .\src\Captail\Captail.csproj --locked-mode
dotnet build .\Captail.sln -c Debug --no-restore

The first build acquires the pinned OBS and FFmpeg runtimes when they are missing.

Read CONTRIBUTING.md before submitting changes. Release maintainers should use docs/RELEASING.md; published binaries are built and verified by GitHub Actions.

License and attribution

Captail is licensed under GNU GPL-2.0-or-later.

Captail uses libobs and selected OBS Studio runtime components. See THIRD_PARTY_NOTICES.md.

Captail is not affiliated with or endorsed by NVIDIA or OBS Project. NVIDIA and ShadowPlay are trademarks of NVIDIA Corporation.