Function libheif_sys::heif_context_set_max_decoding_threads

pub unsafe extern "C" fn heif_context_set_max_decoding_threads(
    ctx: *mut heif_context,
    max_threads: c_int
)

If the maximum threads number is set to 0, the image tiles are decoded in the main thread. This is different from setting it to 1, which will generate a single background thread to decode the tiles. Note that this setting only affects libheif itself. The codecs itself may still use multi-threaded decoding. You can use it, for example, in cases where you are decoding several images in parallel anyway you thus want to minimize parallelism in each decoder.