How to fuse variable size feature with a fixed size feature

Hi guys :smiley:

Recently, Im working on a project, I got an encoder-decoder like generator, and the inputs I feed into the generator are vary in size (which is [batch_size, 1, x]). The output size of the bottleneck is [batch_size, 512, y], where y is depend on the input of the generator. I want to fuse this bottleneck output with a feature with size [batch_size, 1, 512], and the fused feature is still with size [batch_size, 512, y]. Is there a way to do this?

Thanks.