TackleCast

A lightweight, GPU-accelerated capture card viewer for Windows. No recording, no bloat, just your game on your screen.

Built for capture cards like the Genki ShadowCast, Elgato, AVerMedia, and other UVC-compliant devices. Written in Rust with a zero-copy GPU pipeline for minimal latency.

Features

• GPU-accelerated rendering via wgpu with a custom YUV-to-RGB shader
• NVIDIA GPU MJPEG decode via nvJPEG/CUDA (automatic fallback to software decode)
• Zero-copy GPU pipeline - decoded frames never leave the GPU (CUDA to DX12 to wgpu)
• Low-latency audio passthrough via WASAPI
• Resolution options - 720p, 1080p, 1440p, 4K
• FPS modes - 30, 60, 120, or Custom (30-240)
• Live FPS counter with real measured framerate
• Auto-detect capture cards via DirectShow
• Dark theme UI with pause-style settings menu (egui)
• Fullscreen support (F11 or toggle in settings)
• Zero recording overhead - purely a viewer
• Settings persistence - remembers your device selections
• Diagnostic logging - rotating log files for troubleshooting

Quick Start

1. Download the latest release zip from Releases
2. Extract anywhere
3. Double-click TackleCast.exe

No additional software required.

Building from Source

See BUILD.md for full build instructions.

cargo build --release

Controls

Action	Key
Open/close settings	Escape
Fullscreen	F11

How It Works

TackleCast has a three-tier decode pipeline that automatically selects the best path for your hardware:

Tier	Path	When
Zero-copy	nvJPEG decode to shared DX12 buffer to wgpu	NVIDIA GPU with CUDA support
GPU decode + readback	nvJPEG decode to host memory to wgpu	CUDA available, DX12 interop unavailable
Software decode	ffmpeg CPU decode to wgpu	No CUDA/nvJPEG available

At 60 FPS and below, most capture cards output raw NV12 with zero decode overhead. Above 60 FPS, MJPEG is used and benefits from GPU decode.

Architecture

src/
  main.rs          - winit event loop, app state, settings
  capture.rs       - DirectShow capture via ffmpeg-next, format/resolution fallback
  gpu_decode.rs    - NVIDIA nvJPEG GPU MJPEG decode (feature-gated: gpu-decode)
  dx12_interop.rs  - DX12 shared buffers for CUDA/wgpu zero-copy (feature-gated: gpu-decode)
  render.rs        - wgpu DX12 renderer, YUV->RGB WGSL shader
  audio.rs         - WASAPI audio passthrough via cpal
  ui.rs            - egui overlay and settings menu
  devices.rs       - DirectShow video + WASAPI audio device enumeration
  settings.rs      - JSON settings load/save
  logger.rs        - Rotating file logger via tracing

Known Limitations

• GPU decode is NVIDIA-only (AMD AMF and Intel Quick Sync planned for a future release). Non-NVIDIA GPUs fall back to software decode automatically.
• Windows only (DirectShow capture, WASAPI audio, DX12 rendering).
• Some capture cards may throttle at high framerates. Smaller USB passthrough dongles (e.g. Genki ShadowCast 2 Pro) can thermally throttle their internal MJPEG encoder at sustained 1440p@120fps, causing frame delivery to drop to ~60fps. This is a hardware limitation, not a software issue. Devices with better thermal design (e.g. ShadowCast 3) are unaffected.
• Laptop GPUs may thermal throttle at sustained 4K@60fps or 1440p@120fps (a cooling pad helps).
• Webcams may partially work but are not officially supported.

Acknowledgments

• @NeverForgetful - Testing and QA

License

MIT