Can I use TimeStretch on Mel-frequency spectrograms?

As the title implies, I’m wondering if the time-stretching algorithm used by the TimeStretch transform can be used with Mel-frequency spectrograms. I have two choices:

  • Spectrogram() → TimeStretch() → MelScale()
  • MelSpectrogram() → TimeStretch()

Which one is valid? both? neither? thanks in advance :slight_smile: