Support images as chapter marks

Expected behavior of the wanted feature

There are some podcasts who use images as chapter marks and mostly only mobile apps (for example AntennaPod) support the display of this images.

Recently someone works on a player to bring this feature to us windows users: https://mp3chapters.github.io/player/

The developer made his code open source so maybe you can use this as inspiration on how to extract the ids from the mp3 files: https://github.com/mp3chapters/mp3chapters.github.io

Your player mpv has already the feature to show chapters as text and the feature to show covers as image in the gui so this would be just a step further to also show the images of the chapter marks like in this screenshot: https://mp3chapters.github.io/player/screenshot.jpg

Just to be clear: I don't expect seeing the images in the chapter list. It would be enough for me to see the images like the cover image one at a time once the chapters are reached.

Additional information about chapter marks with sample files: https://auphonic.com/blog/2013/07/03/chapter-marks-and-enhanced-podcasts/

Alternative behavior of the wanted feature

No response

Log File

No response

Sample Files

The following example files are used to demonstrate chapters:

Auphonic Chapter Marks Demo, MP4
Auphonic Chapter Marks Demo, MP3
Auphonic Chapter Marks Demo, Opus
Auphonic Chapter Marks Demo, Ogg Vorbis

Start by reproducing the requested behavior with the linked Auphonic MP3, MP4, Opus, and Ogg Vorbis samples. Read the linked mp3chapters player and source for how chapter-image IDs are extracted, then trace mpv’s existing chapter-text and cover-image handling. Done means displaying each chapter image as its chapter is reached without adding images to the chapter list.