When the docs say [3,16,112,112] they are not including the batch size in those dimensions. You still need a batch size for the input so it would look more like this [64,3,16,112,112]. When the error comes back and says you need that shape  [64, 3, 3, 7, 7]  you can pretty much ignore that shape because it doesn’t matter. All you need to focus on is the number of dimensions in this case and just use the image dimensions from the docs.