docstr: Recovers waveform from quantized values.
docstr_tok: ["Recovers","waveform","from","quantized","values","."]
code: def mulaw_decode(wav, qc):
      """Recovers waveform from quantized values."""
      mu = 2**qc - 1
      x = np.sign(wav) / mu * ((1 + mu) ** np.abs(wav) - 1)
      return x
  
imports: import librosa
  import soundfile
  import numpy
  import scipy.io.wavfile
  import scipy.signal
  from TTS.tts.utils.data import StandardScaler
label_desc: Use image node_id 29 for calling the AudioProcessor obj's underlying member method code with example usage: obj.mulaw_decode(wav, qc) and returns: x