Readme updated

README.md

@@ -1 +1,188 @@
 # Splitter
+
+Splitter is a command line tool for cutting video files into equal length or fixed length segments using FFmpeg.  
+It supports multi threaded splitting, ETA and speed reporting, flexible duration formats, and a simple terminal user interface.
+
+This tool is intended for creators, archivists, and automation workflows that need fast and predictable video segmentation.
+
+---
+
+## Features
+
+- Multi threaded splitting for high performance
+- Equal length segments (default)
+- Fixed length segments with the `--force` option
+- Flexible duration formats (`Ns`, `NmMs`, or plain seconds)
+- Estimate only mode (`--estimate`)
+- Terminal progress display with ETA and speed
+- Custom output filename masks
+- FFmpeg passthrough for advanced users
+- Cross platform (.NET 10)
+
+---
+
+## Requirements
+
+- FFmpeg and FFprobe installed and available in the system PATH
+- .NET 10 SDK or newer
+
+---
+
+## Usage
+
+```
+splitter <input.mp4> <output_folder> [options] [--] <ffmpeg passthrough>
+```
+
+---
+
+## Options
+
+### --duration=<value>
+
+Overrides the default 60 second target chunk size.
+
+Accepted formats:
+
+| Format | Meaning |
+|--------|---------|
+| Ns | N seconds |
+| NmMs | N minutes and M seconds |
+| N | N seconds (plain number) |
+
+Examples:
+
+```
+--duration=90s
+--duration=2m30s
+--duration=45
+```
+
+Without `--force`, the program adjusts the segment length so that all segments are equal.
+
+---
+
+### --force
+
+Uses the duration exactly as provided.  
+The last segment may be shorter.
+
+Example:
+
+```
+--duration=45 --force
+```
+
+---
+
+### --estimate
+
+Prints calculated segment information and exits.  
+No splitting is performed.
+
+Example:
+
+```
+splitter video.mp4 out/ --duration=2m30s --estimate
+```
+
+---
+
+### --mask=<pattern>
+
+Custom output filename pattern.
+
+Default:
+
+```
+<OriginalName>_Seg%03d.mp4
+```
+
+Supports:
+
+- `%03d` for zero padded index
+- `%d` for plain index
+
+Example:
+
+```
+--mask="Part_%03d.mp4"
+```
+
+---
+
+### FFmpeg passthrough
+
+Anything after `--` is passed directly to FFmpeg.
+
+Example:
+
+```
+splitter video.mp4 out/ -- -an -sn
+```
+
+---
+
+## How It Works
+
+1. Reads total duration using ffprobe  
+2. Parses the target duration (default 60 seconds or from `--duration=`)  
+3. Computes the number of segments  
+4. If not forced, adjusts segment length so all segments are equal  
+5. Runs multiple FFmpeg processes in parallel  
+6. Displays progress, ETA, and speed in the terminal  
+
+---
+
+## Examples
+
+Split into equal 60 second segments:
+
+```
+splitter video.mp4 out/
+```
+
+Split into equal 90 second segments:
+
+```
+splitter video.mp4 out/ --duration=90s
+```
+
+Split into fixed 45 second segments:
+
+```
+splitter video.mp4 out/ --duration=45 --force
+```
+
+Estimate only:
+
+```
+splitter video.mp4 out/ --duration=2m30s --estimate
+```
+
+Custom output names:
+
+```
+splitter video.mp4 out/ --mask="Clip_%03d.mp4"
+```
+
+Pass extra flags to FFmpeg:
+
+```
+splitter video.mp4 out/ -- -an -sn
+```
+
+---
+
+## Building
+
+```
+dotnet build
+```
+
+Or run directly:
+
+```
+dotnet run -- video.mp4 out/
+```
+