Solved by Nikronic in post #2 
              
              
                Hi, 
The reason that documentation says it expects 112x112 is that the official paper of Kinetic400 which demonstrated benchmarks for 3DConvNets, have used random crop to 112x112 as a data augmentation process. Section 4.3 and 4.4 of have explained the procedure. 
And as you have mentioned, in model…