Inversing AOV Depth Image Sequence to actual depth

Unity's shader function for converting raw depth buffer values to linear view-space depth is as follows;

 // Where:
 //  z - raw depth
 //  _ZBufferParams - x is (1-far/near), y is (far/near), z is (x/far) and w is (y/far)
 inline float LinearEyeDepth( float z )
 {
     return 1.0 / (_ZBufferParams.z * z + _ZBufferParams.w);
 }

Using that information, we can simplify the above into a function useable in C#;

 float LinearEyeDepth (Camera camera, float depth)
 {
     float n = 1f / camera.nearClipPlane;
     float f = (1f / camera.farClipPlane) - n;
     return 1f / (f * depth + n);
 }

Keep in mind that this is still view-space depth - you'll need to do some additional calculations to translate that to actual 3D distance from the camera.