Spectrogram & Melspectrogram
==============================

This file shows how RytmForge library could generate a spectrogram of an audio file.
For convenience this examples uses `librosa.examples` and `librosa.load` functions to load audio from the Internet.
On your local machine you could use `rythmforge.load.load` function to load any `.wav` file.

Load an example audio file
.. code-block:: python

   y, sr = librosa.load(librosa.ex('brahms'))

Compute STFT matrix that is used in both spectrogram and melspectrogram
.. code-block:: python

   S = rythm_forge.core.stft(y, n_fft=2048, hop_size=512)

Spectrogram
-------------
Display the power spectrogram:

.. code-block:: python

    S_dB = rythm_forge.core.amplitude_to_dB(np.abs(S), np.max(S)).astype(np.float64)
    fig, ax = plt.subplots(figsize=(8, 5))
    img = rythm_forge.display.spectrogram(S_dB, yaxis="log", ax=ax)

    fig.colorbar(img, ax=ax, format='%+2.0f dB')
    ax.set(title='Bhams log-frequency spectrogram')
    plt.show()

.. image:: images/spectrogram.png
   :width: 600px
   :align: center

Melspectrogram
---------------

.. code-block:: python

    S_dB = rythm_forge.core.power_to_dB(S, ref=np.max)
    fig, ax = plt.subplots(figsize=(8, 5))

    img = rythm_forge.display.spectrogram(S_dB, yaxis="log", ax=ax)
    fig.colorbar(img, ax=ax, format='%+2.0f dB')
    ax.set(title='Bhams mel-frequency spectrogram')
    plt.show()

.. image:: images/melspectrogram.png
   :width: 600px
   :align: center