Libheif uses libde265 for actually decoding the HEIC image data. which options you use when compiling the program can make a huge difference in performance.

You might not have compiled libheif and its dependencies in the most efficient matter, or have used the most efficient parameters during runtime of your program. This includes making it very easy for app developers (first or third party) to take advantage of hardware accelerated decoding. This means that software taking advantage of that feature can do hardware accelerated image decoding - which is generally much faster than purely CPU-based image decoding.Īpple engineers spent a lot of time and effort optimising the software for decoding HEIC-files as they are widely used throughout the iOS system. iPhone 7 and newer) has hardware decoding built-in. IOS devices with an A10 or newer CPU (i.e. There are several reasons why the built-in iOS photo viewer is fast whereas your own libheif-based decoder is slow: I'm going to assume you mean 'libheif' where you wrote 'libheic' (the former is a popular library for decoding HEIC files, whereas the latter is not something that can be found anywhere).

Heic picture viewer