class_docstr: Conventional frontend structure for TTS.
  
  Stft -> amplitude-spec -> Log-Mel-Fbank
code: def output_size(self) -> int:
      return self.n_mels
  
file_path: espnet/espnet2/s2st/tgt_feats_extract/log_mel_fbank.py
imports: from typing import Any, Dict, Optional, Tuple, Union
  import humanfriendly
  import torch
  from typeguard import check_argument_types
  from espnet2.layers.log_mel import LogMel
  from espnet2.layers.stft import Stft
  from espnet2.s2st.tgt_feats_extract.abs_tgt_feats_extract import AbsTgtFeatsExtract
label_desc: Use image node_id 2 for calling the LogMelFbank obj's underlying member method code with example usage: obj.output_size() and returns: self