why the model input shape is not equal output shape

[Gitxiaoke]

the model input shape is 【1，4，257】，while the output shape is 【1，5，257】，

[YangangCao]

@Gitxiaoke I contacted the author of this paper, he told me like that

[CaiBailin]

I think because the βt,f?
I reference part of artical:
To address the first inequality we designed the network to output βt,f from the last layer with a softplus activation function as follows.

[CaiBailin]

I think because the βt,f? I reference part of artical: To address the first inequality we designed the network to output βt,f from the last layer with a softplus activation function as follows.

But I'm not sure.

[cwhweew]

I think one pair of PHM need 5 outputs，the paper output channel is 10，because of two pair of PHM mask