Draft: Equalizer Settings Persistence equalizer.c

Equalizer Settings Persistence

Issue

Currently, VLC's equalizer does not save custom slider settings between sessions. While the equalizer remains enabled after restarting VLC, the individual band settings revert to their defaults. This is a longstanding inconvenience for users who expect their custom EQ settings to be retained across restarts.

Solution

This merge request implements persistent storage for equalizer settings by:

1. Adding individual configuration options for each band's gain setting
2. Saving band settings when they are modified through the GUI
3. Loading saved settings on startup
4. Maintaining preset selection state

Technical Details

• Added new configuration options equalizer-band-0 through equalizer-band-9 to store individual band gains
• Modified BandsCallback to save individual band settings when changed
• Updated PresetCallback to save both preset name and individual band settings
• Enhanced Open function to load saved settings on startup
• Maintained backward compatibility with existing preset system

Testing

The changes have been tested to ensure:

• Custom band settings persist between VLC restarts
• Preset selection is maintained
• Settings are properly loaded on startup
• No regression in existing equalizer functionality

Related Issues

Fixes #22480 - Equalizer settings not saved between sessions