USES `ref_channel` usage about espnet

[Emrys365]

Thank you for your report! Yes, you are correct. This is from a previous implementation that handles the ref_channel inside the ChannelTAC block. Later I decided to move it to the outer ATFBlock block for more unified processing. So this argument will have no effect for now. But I leave it there for possible extensions in the future.

[sw005320]

Thanks!
@Emrys365, can you confirm it?

[faroit]

Hi, and thanks @sw005320 for looking into this. I guess this is fine and just something left from a previous implementation. The reference channels is used in the paths blocks:

espnet/espnet2/enh/layers/uses.py

Lines 262 to 263 in eed7751

	if input.size(1) > 1 and ref_channel is not None:
	input = input[:, ref_channel].unsqueeze(1)

[faroit]

Thanks @sw005320 @Emrys365 all good then!