    def forward(self, src_tokens, src_lengths=None, return_all_hiddens=False, **kwargs):
        """
        src_tokens: padded tensor (B, T, C * feat)
        src_lengths: tensor of original lengths of input utterances (B,)
        """
        src_tokens, src_lengths = self.add_eos(src_tokens, src_lengths)
        enc_out = self.encoder(src_tokens, src_lengths, return_all_hiddens)
        enc_out = self.apply_adapter(enc_out)
        return enc_out
src_tokens: padded tensor (B, T, C * feat)
src_lengths: tensor of original lengths of input utterances (B,)
examples/speech_text_joint_to_text/models/s2t_dualinputtransformer.py