Add Fade-In and Fade-Out Options

Expected behavior of the wanted feature

Add options for fade-out and fade-in effects when transitioning between tracks or when pausing and resuming music playback in MPV.

The fade-out effect would occur when the song is paused, and the fade-in effect would apply when resuming the song.

The fade-out and fade-in functionality for smoother audio transitions is not currently available in MPV.

Alternative behavior of the wanted feature

The current behavior of MPV, without fade effects, can be abrupt when pausing or resuming music playback.
A smoother transition is desired, like in other music players.

Log File

Adding fade-in and fade-out options would provide a smoother listening experience by reducing the abruptness of audio transitions when pausing or resuming music.

This would make MPV more user-friendly for music playback, similar to other popular media players like VLC or Spotify, which already offer these features.

Sample Files

No response

The issue names no source files, tests, or entry points. Start by clarifying the requested fade behavior for pausing, resuming, and track transitions, then identify the relevant MPV playback code and tests; done should include specified fade-in and fade-out options with verified smoother transitions.