Audio Features and Vamp Plugins¶

General outline¶

To be propagated to https://www.doc.gold.ac.uk/~mas01cr/teaching/dhoxss15/

1. Introductory notes and slides on acoustics and audio (CR)
2. Sonic Visualiser - hands on with waveform and spectrograms (CC)
3. Introductory notes and slides on audio features (CC)
4. Sonic Visualiser - hands on with Vamp plugins (CC)
5. Python/IPython intro (CR)
6. Feature Extraction using Vamp Plugins in Python (IPython Notebook) (CC)
7. Audio Indexing and Search in Python (IPython Notebook) (CR)

Breakdown of CC sections¶

Sonic Visualiser - hands on with waveform and spectrograms¶

1. Waveform
   1. Start Sonic Visualiser and open "A Friendly Warning"
   2. Show dragging through the file using Navigate tool, and also using the overview at bottom
   3. Play from the start, just to get an idea what it sounds like
   4. Return to the start and zoom in (using the zoom wheel, but noting that the mouse wheel also works)
   5. Notice the different shapes in waveform resulting from different types of synthetic percussive sound (low-frequency kick drum / higher frequency cymbal-type sounds) - refer back to Christophe's notes about correspondence between e.g. signal voltage and speaker cone deflection
   6. Continue until the vocal starts, and observe that we can see very little that relates to e.g. sung pitch, although if we zoom in we can quite clearly see sibilance (these frequencies around 10kHz are pretty much the sweet spot for visibility in a 44.1kHz waveform)
   7. We will return to this track

1. Spectrogram
   1. New session, open piano-scale.wav and play it
   2. Some information can sort-of be perceived and measured from the waveform here. Zoom in to the first note, switch to Select mode, drag out one cycle - it's about 170 samples, so 44100/170 = 259 Hz - the note is a middle C so true value should be nearer to 261, but this is a fair approximation

Introductory notes and slides on audio features¶

Sonic Visualiser - hands on with Vamp plugins¶

Feature Extraction using Vamp Plugins in Python¶

Materials¶

• Audio features slides: PDF, PowerPoint

• IPython Notebook for Vamp Plugins in Python