SRT to 3D Subtitles

Convert standard .srt subtitles into .ass format, offset so they display correctly in 3D video playback.

The Problem

When watching 3D movies (Side-by-Side, Over-Under, Anaglyph), centered subtitles get split between the left and right eye views, making them disorienting to read. This tool converts standard .srt subtitles into a 3D-compatible .ass format that keeps each eye's subtitles in the correct position.

Features

• SBS (Side-by-Side) — subtitles split left/right for each eye
• OU (Over-Under) — subtitles split top/bottom for each eye
• Anaglyph (Red/Green) — subtitles offset with red/green color channels
• CLI — full command-line interface with configurable options
• GUI — lightweight Windows interface for easier mode selection
• Formatting support — converts HTML tags (<b>, <i>, <u>, <font color>) to ASS format codes
• Resolution scaling — adjusts subtitle positioning based on target resolution

Usage

The application runs in two modes — GUI (no arguments) and CLI (with arguments).

GUI

1. Launch ConvertSRTto3DASS.exe (or the Linux/macOS binary)
2. Select your .srt input file
3. Choose your 3D mode (SBS, OU, or Anaglyph)
4. Adjust settings as needed
5. Click Convert

Note: The GUI is experimental. Feedback and bug reports are welcome!

Command Line

The CLI runs on Windows, Linux, and macOS.

Drag and drop:

1. Drag and drop an .srt file onto ConvertSRTto3DASS
   • Uses default settings (SBS mode, 1280x720)
2. The resulting .ass file will be saved in the same directory as the .srt

Command line:

ConvertSRTto3DASS.exe input.srt [options]

Available options:

--mode sbs|ou|rg              3D mode (default: sbs)
--resx <number>               Output width
--resy <number>               Output height
--baseresx <number>           Scaling reference width (default: 1280)
--baseresy <number>           Scaling reference height (default: 720)
--fontsize <number>           Font size (default: 16)
--offsetx <number>            RG eye separation
--bottomoffset <number>       RG bottom offset
--sbssidemargin <number>      SBS side margin
--outopmargin <number>        OU top subtitle margin
--verticalmargin <number>     General vertical margin
--output <path>               Output file path
--help, -h, /?                Show help

Examples:

ConvertSRTto3DASS.exe movie.srt --mode sbs
ConvertSRTto3DASS.exe movie.srt --mode ou --resx 1920 --resy 1080
ConvertSRTto3DASS.exe movie.srt --mode rg --offsetx 6 --bottomoffset 24

Known Issues

• Subtitle positional data from .srt files is stripped during conversion.

Requirements

• .NET 8 SDK — required to build
• Windows — the GUI runs on Windows
• Linux/macOS — the CLI runs cross-platform

Building

# Build all projects
dotnet build

# Publish CLI (self-contained)
## Linux x64
dotnet publish ConvertSRTto3DASS.Cli -c Release -r linux-x64 --self-contained true -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true
## OSX x64
dotnet publish ConvertSRTto3DASS.Cli -c Release -r osx-x64 --self-contained true -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true
## OSX arm64
dotnet publish ConvertSRTto3DASS.Cli -c Release -r osx-arm64 --self-contained false -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true
## Windows x64
dotnet publish ConvertSRTto3DASS.Cli -c Release -r win-x64 --self-contained true -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true

# Publish GUI (Windows x64 only, self-contained)
dotnet publish ConvertSRTto3DASS.Gui -c Release -r win-x64 --self-contained true -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true

Each publish produces a single .exe with no .dll sidecars.

License

MIT License — Copyright © imrayya 2021-2026

Contributing

Contributions are welcome. Please open an issue or submit a pull request.

Contributors

• imrayya — project owner
• jae0815
• fabio-noga
• kaiju466

Disclaimer

This is a personal hobby project. The codebase is functional but not production-grade — minimal comments, no tests, and some rough edges. Use at your own discretion.