docs: enhance compression documentation and update links

- Added a new compression guide detailing the process and requirements for compressing downloaded media files.
- Updated links in the FAQ and troubleshooting sections to point to the new compression guide for better user navigation and clarity.

Author: 3dnsfw

docs/src/content/docs/help/faq.md

@@ -90,7 +90,7 @@ This converts:
 - JPG/JPEG → JPEG XL (30-50% smaller)
 - MP4 → AV1 (30-50% smaller)
 
-See the [README](https://github.com/3dnsfw/kemono-scraper#compression) for requirements.
+See the [Compression guide](/Kemono-Scraper/usage/compression/) for detailed instructions and requirements.
 
 ---
 

docs/src/content/docs/help/troubleshooting.md

@@ -243,7 +243,7 @@ Large creators can have hundreds of gigabytes of content. Monitor your disk spac
 
 1. Using `--maxPosts` to limit downloads
 2. Downloading to an external drive
-3. Compressing files after download
+3. [Compressing files after download](/Kemono-Scraper/usage/compression/) to save 30-50% disk space
 
 ---
 

docs/src/content/docs/usage/compression.md

@@ -0,0 +1,237 @@
+---
+title: Compression
+description: Compress downloaded media files to save disk space
+sidebar:
+  order: 5
+---
+
+After downloading files, you can compress them to save significant disk space. The scraper includes a built-in compression script that converts images and videos to more efficient formats.
+
+## What Gets Compressed
+
+The compression script automatically processes:
+
+- **Images**: JPG/JPEG → JPEG XL (typically 30-50% smaller)
+- **Videos**: MP4 → AV1 (typically 30-50% smaller)
+
+The scraper automatically detects compressed files on subsequent runs, so you won't re-download files that have already been compressed.
+
+## Requirements
+
+Before you can use compression, you need to install the required tools:
+
+### libjxl (for JPEG XL)
+
+**Linux:**
+
+```bash
+# Arch Linux / Manjaro
+paru -S libjxl
+# or
+sudo pacman -S libjxl
+
+# Debian / Ubuntu
+sudo apt install libjxl-tools
+```
+
+**Windows:**
+
+```powershell
+winget install --id=libjxl.libjxl -e
+```
+
+**macOS:**
+
+```bash
+brew install jpeg-xl
+```
+
+### ffmpeg (with SVT-AV1 support)
+
+**Linux:**
+
+```bash
+# Arch Linux / Manjaro
+paru -S ffmpeg
+# or
+sudo pacman -S ffmpeg
+
+# Debian / Ubuntu
+sudo apt install ffmpeg
+```
+
+**Windows:**
+
+```powershell
+winget install ffmpeg
+```
+
+**macOS:**
+
+```bash
+brew install ffmpeg
+```
+
+:::tip[Verify Installation]
+Check that the tools are installed correctly:
+
+```bash
+cjxl --version
+ffmpeg -version
+```
+
+:::
+
+## Running Compression
+
+### Basic Usage
+
+Navigate to your project directory and run:
+
+```bash
+bun run compress
+```
+
+This will compress all eligible files in your download directories.
+
+### On Windows PowerShell
+
+You can also use the PowerShell script:
+
+```powershell
+.\compress.ps1
+```
+
+### On Windows/Linux/Mac (Shell Script)
+
+```bash
+./compress.sh
+```
+
+## Configuration
+
+You can customize compression settings using environment variables:
+
+### Environment Variables
+
+```bash
+JPEG_XL_QUALITY=95 AV1_CRF=28 bun run compress
+```
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `JPEG_XL_QUALITY` | 90 | JPEG XL quality (1-100, higher = better quality) |
+| `JPEG_XL_EFFORT` | 7 | Encoding effort (1-9, higher = slower but smaller files) |
+| `AV1_CRF` | 30 | AV1 quality (lower = better, 18-35 typical range) |
+| `AV1_PRESET` | 6 | SVT-AV1 preset (0-13, lower = slower but better quality) |
+
+### Windows PowerShell Parameters
+
+On Windows PowerShell, you can pass parameters directly:
+
+```powershell
+.\compress.ps1 -JpegXlQuality 95 -Av1Crf 28
+```
+
+## Understanding Quality Settings
+
+### JPEG XL Quality
+
+- **Lower values (70-85)**: Smaller files, slight quality loss
+- **Default (90)**: Good balance of quality and size
+- **Higher values (95-100)**: Near-lossless, larger files
+
+### JPEG XL Effort
+
+- **Lower (1-3)**: Fast encoding, larger files
+- **Default (7)**: Good balance
+- **Higher (8-9)**: Slow encoding, smallest files
+
+### AV1 CRF (Constant Rate Factor)
+
+- **Lower (18-25)**: Higher quality, larger files
+- **Default (30)**: Good balance
+- **Higher (31-35)**: Lower quality, smaller files
+
+### AV1 Preset
+
+- **Lower (0-3)**: Slowest encoding, best quality
+- **Default (6)**: Good balance
+- **Higher (10-13)**: Fast encoding, slightly lower quality
+
+## Examples
+
+### High Quality Compression
+
+For maximum quality (larger files):
+
+```bash
+JPEG_XL_QUALITY=98 JPEG_XL_EFFORT=9 AV1_CRF=25 AV1_PRESET=4 bun run compress
+```
+
+### Maximum Compression
+
+For smallest file sizes (some quality loss):
+
+```bash
+JPEG_XL_QUALITY=85 JPEG_XL_EFFORT=9 AV1_CRF=32 AV1_PRESET=8 bun run compress
+```
+
+### Balanced (Default)
+
+The default settings provide a good balance:
+
+```bash
+bun run compress
+```
+
+## How It Works
+
+1. The script scans your download directories for uncompressed files
+2. Images (JPG/JPEG) are converted to `.jxl` format
+3. Videos (MP4) are converted to `_av1.mp4` format
+4. Original files are preserved alongside compressed versions
+5. On subsequent scraper runs, compressed files are detected and skipped
+
+:::note
+The original files are kept. You can delete them manually after verifying the compressed versions work correctly.
+:::
+
+## Troubleshooting
+
+### "Command not found: cjxl"
+
+Make sure `libjxl` is installed and in your PATH. Verify with:
+
+```bash
+which cjxl
+```
+
+### "ffmpeg: command not found"
+
+Install `ffmpeg` and ensure it's in your PATH:
+
+```bash
+which ffmpeg
+```
+
+### Compression is very slow
+
+- Lower `JPEG_XL_EFFORT` (try 5-6)
+- Increase `AV1_PRESET` (try 8-10)
+- Process files in smaller batches
+
+### Files are too large after compression
+
+- Lower `JPEG_XL_QUALITY` (try 85-90)
+- Increase `AV1_CRF` (try 32-35)
+
+### Files are too small / quality is poor
+
+- Increase `JPEG_XL_QUALITY` (try 95-98)
+- Lower `AV1_CRF` (try 25-28)
+
+## Next Steps
+
+- Learn about [basic usage](/Kemono-Scraper/usage/basic/) for downloading files
+- See [command line options](/Kemono-Scraper/usage/cli-options/) for more control