First version of the script.

.gitignore

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+*.mdd
+*.blend
+*.blend?
+videos

face_track.py

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+#!/usr/bin/env python3
+
+from struct import pack
+import numpy as np
+import cv2 as cv
+import mediapipe as mp
+
+if __name__ == "__main__":
+    mp_face_mesh = mp.solutions.face_mesh
+    
+    # Compute the mesh points.  One mesh per frame.
+    meshes = []
+    point_count = 0
+    aspect_ratio = 1.0
+    with mp_face_mesh.FaceMesh(
+        static_image_mode=False, # Set false for video.
+        max_num_faces=1,
+        refine_landmarks=True,
+        min_detection_confidence=0.5) as face_mesh:    
+
+        i = 1
+        cap = cv.VideoCapture("videos/BDGFACE 5_12.mp4")
+        while cap.isOpened():
+            print("\rReading frame", i, end = "")
+            ret, image = cap.read()
+            if not ret:
+                break
+
+            aspect_ratio = image.shape[1] / image.shape[0]
+            results = face_mesh.process(cv.cvtColor(image, cv.COLOR_BGR2RGB))    
+            if not results.multi_face_landmarks:
+                meshes += [None]
+            else:
+                point_count = len(results.multi_face_landmarks[0].landmark)
+                meshes += [results.multi_face_landmarks[0].landmark]
+            
+            i += 1
+        cap.release()
+    print("\rRead {} frames.                 ".format(len(meshes)))
+    
+    # Write the mdd file.
+    fps = 24.0  # TODO: get this from the video file.
+    frame_count = len(meshes)
+    if frame_count > 0:
+        with open("test.mdd", 'wb') as mdd:
+            print("Vert count:", point_count)
+        
+            mdd.write(pack(">2i", frame_count, point_count))
+            mdd.write(pack(">%df" % (frame_count), *[frame / fps for frame in range(frame_count)]))
+
+            i = 1
+            for mesh in meshes:
+                print("\rWriting frame", i, end = "")
+                if mesh is None:
+                    # Put all vertices at the origin for bogus frames.
+                    for n in range(point_count):
+                        mdd.write(pack(">3f", 0.0, 0.0, 0.0))
+                else:
+                    for point in mesh:
+                        mdd.write(pack(">3f", point.x, point.y / aspect_ratio, point.z))
+                i += 1
+    print()
+            

shell.nix

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+let
+    # You can replace "unstable" with any channel name to use that channel.
+    pkgs = import <unstable> {};
+    pypkgs = pkgs.python310Packages;
+    name = "face_track_dev_env";
+in pkgs.stdenv.mkDerivation {
+    inherit name;
+    nativeBuildInputs = with pkgs; [
+        pypkgs.python
+        pypkgs.pip
+        pypkgs.numpy
+        pypkgs.opencv4
+        pypkgs.dlib
+    ];
+
+    shellHook = with pkgs; ''
+        export PYTHON_LIBRARY="${pypkgs.python.libPrefix}"
+        export PYTHON_LIBPATH="${pypkgs.python}/lib"
+        export PYTHON_INCLUDE_DIR="${pypkgs.python}/include/${pypkgs.python.libPrefix}"
+        export PYTHON_VERSION="${pypkgs.python.pythonVersion}"
+        export PYTHON_NUMPY_PATH="${pypkgs.numpy}/${pypkgs.python.sitePackages}"
+        export PYTHON_NUMPY_INCLUDE_DIRS="${pypkgs.numpy}/${pypkgs.python.sitePackages}/numpy/core/include"
+        export PYTHONPATH="$PYTHONPATH:$HOME/.local/lib/python3.10/site-packages"
+        export PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python      
+    '';
+}