A process for determining a video of a biometric characteristic as being a spoof or a genuine recording of a live biometric characteristic, wherein the video comprises a temporal sequence of frames (j), the process being implemented in a system comprising a processing unit, comprising the steps of: - preprocessing the video, said preprocessing comprising aligning the biometric characteristic on each frame of the video, - determining a liveness score of the video, said determination comprising, for each frame of a plurality of frames (j): - determining a differential motion intensity of a current frame by computing differences (322, 352) between a motion intensity of said current frame and motion intensities of each frame of a set of frames preceding said current frame, wherein determining the motion intensity of a frame comprises computing a motion component of a magnified phase variation of said frame, wherein the motion component is computed as the sum of differences between the pixels of a frame and the corresponding pixels of the previous frame, - inferring a motion intensity of the video from the differential motion intensities of the plurality of frames, by computing the mean normalized differential motion intensity of the frames, - comparing said motion intensity of the video to a predetermined first threshold, and assigning a liveness score to the video, depending on the comparison of the motion intensity of the video with the first threshold, and - according to the liveness scores of the video, determining whether the video is a genuine recording of a biometric characteristic or a spoof. - preprocessing the video, said preprocessing comprising aligning the biometric characteristic on each frame of the video, - determining a liveness score of the video, said determination comprising, for each frame of a plurality of frames (j): - determining a differential motion intensity of a current frame by computing differences (322, 352) between a motion intensity of said current frame and motion intensities of each frame of a set of frames preceding said current frame, wherein determining the motion intensity of a frame comprises computing a motion component of a magnified phase variation of said frame, wherein the motion component is computed as the sum of differences between the pixels of a frame and the corresponding pixels of the previous frame, - inferring a motion intensity of the video from the differential motion intensities of the plurality of frames, by computing the mean normalized differential motion intensity of the frames, - comparing said motion intensity of the video to a predetermined first threshold, and assigning a liveness score to the video, depending on the comparison of the motion intensity of the video with the first threshold, and - determining a differential motion intensity of a current frame by computing differences (322, 352) between a motion intensity of said current frame and motion intensities of each frame of a set of frames preceding said current frame, wherein determining the motion intensity of a frame comprises computing a motion component of a magnified phase variation of said frame, wherein the motion component is computed as the sum of differences between the pixels of a frame and the corresponding pixels of the previous frame, - inferring a motion intensity of the video from the differential motion intensities of the plurality of frames, by computing the mean normalized differential motion intensity of the frames, - comparing said motion intensity of the video to a predetermined first threshold, and assigning a liveness score to the video, depending on the comparison of the motion intensity of the video with the first threshold, and - according to the liveness scores of the video, determining whether the video is a genuine recording of a biometric characteristic or a spoof.