Sonic Visualiser contains advanced waveform and spectrogram viewers, as well as editors for many sorts of audio annotations. Besides visualisation, it can make and play selections based on the locations of automatically detected features, seamlessly loop playback of single or multiple noncontiguous regions, synthesise annotations for playback, and slow down playback while retaining display synchronisation.

Sonic Visualiser supports the Vamp plugin API for plugins that extract descriptive or analytical data from audio. Vamp plugins for onset, pitch and note detection and tempo tracking using the Aubio library are available, as well as further plugins for tempo tracking,
chromagram analysis, constant-Q spectrogram, spectral centroid, power curve, key estimation, tonal change detection, harmonic spectrogram, and a large number of low-level spectral features. There is also a comprehensive SDK for use by developers of Vamp plugins and hosts.

Features

• Load audio files in WAV, Ogg and MP3 formats, and view their waveforms.
• Look at audio visualisations such as spectrogram views, with interactive adjustment of display parameters.
• Annotate audio data by adding labelled time points and defining segments, point values and
• curves.
  Overlay annotations on top of one another with aligned scales, and overlay annotations on top of
• waveform or spectrogram views.

• View the same data at multiple time resolutions simultaneously (for close-up and overview).
• Run feature-extraction plugins to calculate annotations automatically, using algorithms such as beat trackers, pitch detectors and so on.
• Import annotation layers from various text file formats.
• Import note data from MIDI files, view it alongside other frequency scales, and play it with the original audio.
• Play back the audio plus synthesised annotations, taking care to synchronise playback with display.
• Select areas of interest, optionally snapping to nearby feature locations, and audition individual and comparative selections in seamless loops.
• Time-stretch playback, slowing right down or speeding up to a tiny fraction or huge multiple of the original speed while retaining a synchronised display.
• Export audio regions and annotation layers to external files.

New in v1.3

• There is a new spreadsheet-style data viewer and editor for viewing and editing the data in some types of annotation layer.
• Alignments are now saved to the session file.
• The spectrogram layer is usually somewhat faster than it was.
• You can now hold Shift while dragging to move an item, in order to override the initial drag resistance introduced in 1.2.
• The gross mis-labelling of time lines in the ruler has been fixed.
• There is a new, somewhat provisional PulseAudio output driver.
• Several other bug fixes.