macOS Mojave Custom Dynamic Wallpaper

Question

I've found that the default (and only) dynamic wallpaper in macOS Mojave Beta is in /Library/Desktop Pictures/. The file in question is called "Mojave (Dynamic).heic"

I imagine that the file itself is probably some sort of mapping/dictionary from time values to images, but I haven't been able to open it as any sort of image collection. Sure, I can open it with Preview, but it only shows one of the images.

I believe there has to be a way of creating custom wallpapers similar to this default one. The question is how to open such files properly (to see them as collections) and, more importantly, edit them?

Answer 1

I described here and here how dynamic wallpapers are built. Also I created simple console application which can help with creating custom wallpaper: https://github.com/mczachurski/wallpapper.

Answer 2

The HEIC format is a container for HEIF or High Efficiency Encoding Format. This container allows multiple HEIF-encoded images to be contained within one container. The HEIC file in question contains 16 images that allow the wallpaper to change throughout the day. Currently, there is no software that I can find for the Mac that allows for the encoding of these multi-image HEIC files (collections, as they are technically called). However, I have found a tool that is part of the libde265 library called heif-enc that allows such encoding via a command line interface. I'm still struggling with it to get it to work the way I want, but that should theoretically allow very similarly packaged images to be created.

Sources/More Information:

HEIF: http://nokiatech.github.io/heif/

Libde265: https://www.libde265.org/ and https://github.com/strukturag/libde265

EDIT: Just wanted to clarify a couple of things. I built the libde265 tools on ubuntu, not MacOS. Also I've yet to find if there is something in the EXIF data of that particular wallpaper that tells MacOS which wallpaper to display when, or if the system is just expecting exactly 16 images and displays them in order. Also there's a linux plugin for GIMP that allows opening HEIC files, but in the case of collections, it asks you to choose which image to open and does not allow for the exporting of multi-image collections (at least for now).