Waveform Player

To draw a waveform, the player decodes the file with the Web Audio API and reduces millions of samples to a few thousand peaks: for every horizontal pixel it keeps the highest and lowest sample in that slice. A four-minute song at 44.1 kHz has about 10.6 million samples per channel, but a 1,000-pixel overview needs only 2,000 values. Playback itself runs through the browser’s own audio element, which streams the original file and keeps memory use low.

Speed runs from 0.5× to 2× in 0.05 steps, with presets at the common values. The player turns on the browser’s pitch-preserving mode, so slowing a guitar solo to 0.75× keeps it in the same key instead of dropping it like a slowed-down tape. That is ideal for learning riffs, transcribing lyrics or following a fast lecture. A-B looping repeats a section you drag across the waveform, checked about 30 times a second so the jump back is tight.

Add as many files as you like to the playlist and the next track can start automatically when one finishes. The panel beside the player shows the format, file size, duration, average bitrate and channel count of the current track. Everything runs from your own disk, so unreleased mixes, private recordings and confidential interviews never leave your computer.

Keyboard shortcuts cover everyday listening: Space or K to play and pause, the left and right arrows to jump 5 seconds (1 second with Shift), up and down for volume, N and P for the next and previous track, L for the loop, M to mute, and the square brackets to slow down or speed up. The player is for listening and reviewing; trimming, fading and converting belong to the cutter and converter tools.