Thanks a lot @ptrblck. Here is it - torch.Size([16, 4, 3, 257, 490]). In order : batch size, sequence, channels, height, width.
The arguments are
n_outputs=20
num_layers=2
hidden_dim=150
n_steps=3
cnn=ConvNet(recurrent=True)
cnn = cnn.to(device)
print('CNN runs on ', device)
model=Mixnet( n_outputs, num_layers, hidden_dim, n_steps, cnn)