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ExifTool Auto LUT Detection Guide

This guide explains how to use the new ExifTool-based automatic LUT detection system for MPV.

Overview

The ExifTool Auto LUT script uses exiftool to detect gamma information directly from video files and automatically applies appropriate LUTs. This method is more reliable than XML parsing and works with a wider variety of video files.

Key Features

  • Primary Detection: Acquisition Record Group Item Value: s-log3-cine
  • Fallback Detection: CaptureGammaEquation, TransferCharacteristics, Gamma
  • Fast Switching: Cached metadata for quick playlist navigation
  • Multiple Formats: Supports Sony, Canon, Panasonic, DJI, and more

Supported Gamma Types

Gamma Type LUT File Description
s-log3-cine SLog3SGamut3.CineToLC-709.cube Sony S-Log3 Cine to Rec.709
s-log3 SLog3SGamut3.CineToLC-709.cube Sony S-Log3 to Rec.709
s-log2 SLog3SGamut3.CineToSLog2-709.cube Sony S-Log2 to Rec.709
v-log VLog_to_V709_forV35_ver100.cube Panasonic V-Log to Rec.709
canon-log2 CinemaGamut_CanonLog2-to-Canon709_65_Ver.1.0.cube Canon Log2 to Rec.709
canon-log3 CinemaGamut_CanonLog3-to-Canon709_65_Ver.1.0.cube Canon Log3 to Rec.709
dji-osmo-p3 Neutral_Osmo_P3.cube DJI Osmo Pocket 3 Neutral
rec709 (none) Rec.709 (No LUT needed)

Usage

Automatic Detection

The script automatically detects gamma information when you load a video file in MPV. No manual intervention required.

Manual Processing

Press Ctrl+E in MPV to manually trigger gamma detection and LUT application.

Testing Detection

Use the provided test scripts to verify detection works with your video files:

PowerShell (Recommended):

.\test_exiftool_detection.ps1 "C:\path\to\your\video.mp4"

Batch:

test_exiftool_detection.bat "C:\path\to\your\video.mp4"

Configuration

Edit script-opts/exiftool_auto_lut.conf to customize behavior:

enabled=yes                    # Enable/disable the script
auto_apply=yes                 # Automatically apply LUTs
show_detection=yes             # Show detection results in console
lut_base_path=~~home/lut/      # Base path for LUT files
fast_switching=yes             # Enable fast LUT switching
cache_metadata=yes             # Cache metadata for speed
exiftool_path=exiftool         # Path to exiftool executable
timeout=5                      # Timeout for exiftool execution

Detection Priority

The script uses the following priority order for gamma detection:

  1. Acquisition Record Group Item Value (most reliable for Sony cameras)
  2. CaptureGammaEquation (alternative Sony format)
  3. TransferCharacteristics (standard video metadata)
  4. Gamma (basic gamma information)

Troubleshooting

ExifTool Not Found

Make sure exiftool is installed and available in your PATH:

exiftool -ver

No Detection

  • Check if your video file contains metadata
  • Try the test script to see what metadata is available
  • Some video files may not contain gamma information

Wrong LUT Applied

  • Check the detected gamma value in the console output
  • Add custom mappings to the lut_mapping table in the script
  • Verify the LUT file exists in the lut/ directory

Console Output

When detection is successful, you'll see output like:

=== EXIFTOOL AUTO LUT ===
Video file: sample.mp4
=== METADATA DETECTED ===
Acquisition Record Group Item Value: s-log3-cine
Detected Gamma: s-log3-cine
✓ SUCCESS: Applied: Sony S-Log3 Cine to Rec.709

Performance

  • Caching: Metadata is cached to avoid repeated exiftool calls
  • Fast Switching: Playlist navigation is optimized for speed
  • Background Processing: Detection runs in background to avoid blocking playback

Integration

The script is automatically loaded via mpv.conf:

script=scripts/exiftool_auto_lut.lua

The old XML-based script is disabled to avoid conflicts:

# script=scripts/sony_xml_auto_lut.lua  # Disabled in favor of exiftool detection