Waveform Viewer

How the Waveform Viewer works

Waveform viewer: what to know first

A waveform is the oldest picture of sound there is: time runs left to right, and the height of the trace at each moment is the instantaneous level. Reading one takes a little practice but it tells you a great deal — where the loud and quiet parts are, whether a recording has been squashed flat by a limiter, whether there is a click, a gap or a fade — and it is a much better thumbnail of a piece of audio than a stock icon.

Zooming. The preview waveform on the page shows the whole file. The exported image shows only the selected range, so dragging the handles closer together is how you zoom. The Shown line in the stats reports the range and the zoom factor, and the Image line tells you how many milliseconds each pixel of the export represents. At the full width of a three minute song that is around 100 ms per pixel, which is fine for an overview; zoom into a fraction of a second and it drops below a millisecond, at which point you can see individual cycles of the waveform.

Three styles. Filled draws the envelope — for every pixel column the tool finds the highest and lowest sample in that slice of time and fills between them. It is the classic look and the most honest at low zoom, because it never hides a short spike. Bars draws the same envelope as a row of thin vertical bars with a gap between them, the style used by music players and podcast apps. Line joins successive samples with a single stroke, which only makes sense when you are zoomed in far enough that each pixel covers fewer than two samples; at lower zoom the tool falls back to the filled envelope so the picture stays truthful.

Channels. A stereo file is drawn as two lanes, left above right, so a difference between the channels is visible. Choose Mixed to mono to average them into one lane, which is the usual choice for a decorative image and the right one when the channels are near identical anyway.

Themes and transparency. Five presets cover the common cases — the site's orange on dark, black or blue on white for documents, white on black for video overlays, and a transparent background with a dark trace for placing over your own artwork. The PNG keeps the alpha channel, so the transparent theme composites cleanly in an image editor or a video timeline.

Vertical gain. A quiet recording draws as a thin line down the middle of the image. Rather than normalising the audio, raise the gain to scale the trace; it only affects the picture. Values above 1 will clip the trace at the top and bottom of the lane, which is fine for an illustration and useful for making quiet detail visible.

Time ruler. The ruler adds a strip along the top with tick marks at sensible intervals — every 10 seconds for a song, every 5 ms when zoomed into a transient — labelled in minutes and seconds or in milliseconds as appropriate. Turn it off for a purely decorative image.

Size. The width and height are the pixel dimensions of the exported PNG, up to 8000 pixels wide, which is more than enough for a print-resolution banner. A wide, short image suits a header; a square one suits a social post. Rendering is instant at normal sizes and takes a second or two for very wide images of long files.

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