Function vmaf_read_pictures 

pub unsafe extern "C" fn vmaf_read_pictures(
    vmaf: *mut VmafContext,
    ref_: *mut VmafPicture,
    dist: *mut VmafPicture,
    index: c_uint,
) -> c_int

Read a pair of pictures and queue them for eventual feature extraction. This should be called after feature extractors are registered via vmaf_use_features_from_model() and/or vmaf_use_feature(). VmafContext will take ownership of both VmafPictures (ref and dist) and vmaf_picture_unref().

When you’re done reading pictures call this function again with both ref and dist set to NULL to flush all feature extractors.

@param vmaf The VMAF context allocated with vmaf_init().

@param ref Reference picture.

@param dist Distorted picture.

@param index Picture index.

@return 0 on success, or < 0 (a negative errno code) on error.