Add readme file

Author: egorsmkv

README.md

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+# wav-files-concat
+
+A lightweight Rust CLI tool for concatenating multiple WAV files from a directory (including subdirectories) into a single output WAV file. It ensures all input files have compatible formats (channels, sample rate, and sample format) before proceeding.
+
+## Features
+
+- Recursively scans directories for `.wav` files (case-insensitive).
+- Validates format compatibility across all files.
+- Supports both float (32-bit) and int (16-bit) sample formats.
+- Handles errors gracefully with detailed context using `anyhow`.
+- Includes comprehensive unit tests.
+
+## Installation
+
+### From Source
+
+1. Clone the repository:
+   ```bash
+   git clone https://github.com/RustedBytes/wav-files-concat
+   cd wav-files-concat
+   ```
+
+2. Build and install:
+   ```bash
+   cargo install --path .
+   ```
+
+## Usage
+
+```bash
+wav-files-concat <INPUT_DIR> <OUTPUT_FILE>
+```
+
+- `<INPUT_DIR>`: Path to the directory containing WAV files (required).
+- `<OUTPUT_FILE>`: Path to the output WAV file (required).
+
+The tool will:
+1. Find all WAV files recursively.
+2. Validate they share the same audio spec.
+3. Concatenate them in the order discovered by the filesystem walker.
+
+## Examples
+
+### Basic Usage
+
+Concatenate all WAV files in `./audio/` to `combined.wav`:
+
+```bash
+wav-files-concat ./audio/ combined.wav
+```
+
+Output:
+```
+Scanning input directory for WAV files...
+Found 3 WAV files.
+Determining WAV format from first file...
+Format: 2 channels, 44100 Hz, Float
+Verifying formats of remaining files...
+All files compatible.
+Creating output file: combined.wav
+Concatenating files...
+  1/3: ./audio/track1.wav
+  2/3: ./audio/subdir/track2.wav
+  3/3: ./audio/track3.wav
+Concatenation complete.
+```
+
+### Error Handling
+
+If files have incompatible formats:
+```
+Error: Incompatible WAV format in ./audio/incompatible.wav: WavSpec { channels: 1, sample_rate: 48000, bits_per_sample: 16, sample_format: Int }
+```
+
+If no WAV files are found:
+```
+Error: No WAV files found in the input directory
+```
+
+## Dependencies
+
+This project uses the following crates:
+
+| Crate | Purpose | Version (approx.) |
+|-------|---------|-------------------|
+| `anyhow` | Error handling with context | ^1.0 |
+| `clap` | Command-line argument parsing | ^4.0 |
+| `hound` | WAV file reading/writing | ^3.5 |
+| `walkdir` | Recursive directory traversal | ^2.3 |
+| `tempfile` (dev) | Temporary files for testing | ^3.0 |
+
+See `Cargo.toml` for exact versions.
+
+## Testing
+
+Run the test suite:
+
+```bash
+cargo test
+```
+
+The tests cover:
+- Finding WAV files (including subdirs, case-insensitivity, multiples, and edge cases like no files).
+- Retrieving WAV specs from valid/invalid files.
+- Copying samples with format mismatches.
+
+All tests use temporary directories and mock WAV files for isolation.
+
+## Building
+
+```bash
+cargo build --release
+```
+
+The binary will be in `target/release/wav-files-concat`.