A waveform viewer for Pure Data.
wavview is used to display tables containing audio data. It allows you to explore the data by zooming and scrolling, select an interval, or set an index at a given position.
It is effective for viewing long tables, see here with a 45mn long file:
wavview is fully "vanilla" and doesn't depend on any external library.
Pd >= 0.56 is required though, because wavview uses the new [goprect( message when setting its size.
wavview is built using data structures. The entire width of the display is split into as many elements as there are pixels. For each element, a vertical segment is drawn, going from the minimum to the maximum among the values of the samples contained into the range defined by the element (1 pixel wide * zoom_factor * table_size / display_width).
E.g: if the display is 400 pixels wide, the table contains 40000 samples, and the zoom is 1 (fullscreen), then the first element will be the segment (0.0, min), (0.0, max) where min and max are the minimum and maximum values among the 100 first samples.
This allows to see the peak values, whatever the zoom factor.
Internally, an important optimization is done: when updating to a new table, wavview computes 32-times-successively-downsampled min/max tables, to greatly decrease the CPU load in most drawing cases, at a RAM cost of approximately 1/16 of the initial table size.
For example, if the table is 60'000'000 samples long (~18mn at 48kHz) and the display is 400px wide, at fullscreen zoom each pixel has to take into account less than 5 values (60000000 / 400 / 32 / 32 / 32 = 4.5), instead of 150000 (= 60000000 / 400).
A wavview can be permanently associated to a given table. This way, it retains the calculated peak buffers, that can be reused by another wavview if it needs to display this table.
A timeline is available as a separate wavview_timeline object, so that you can add it only if you need.
It displays evenly spaced time markers, in addition to the time at left and right ends of the visible range.
wavview is written by Antoine Rousseau and licensed as BSD-2.
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