OneTaskBy Tim King · Updated
AB Loop Player
AB Loop Player to Repeat Part of a Song to Practise
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How the A-B Loop Player works
Drop a song or recording in, set point A and point B in seconds, and this AB loop player repeats that passage until you stop it. Slow it down to learn a fast run, nudge the points while it plays to tighten the loop, and watch the repeat count. The file is decoded in your browser and never uploaded.
Musicians learn difficult passages by repetition: play the same four bars over and over, slower at first, until the fingers know them. A-B repeat was a feature on cassette decks and CD players for exactly this, and it is just as useful for transcribing a solo, learning dance steps or picking out a phrase in a language lesson.
Using the AB loop player
Set point A to where the passage starts and point B to where it ends, both in seconds. Leave point B at 0 to loop to the end of the file. Press Play and the section repeats seamlessly; the loop is handled by the browser's audio engine at sample accuracy, so there is no gap at the join. You can change A, B and speed while it plays and the loop updates straight away.
Finding the points. The Position readout shows where playback is. Play from the start with A at 0, note the time where the passage begins, then set A and B around it. Start a little early and end a little late — a loop that begins on the beat before the passage gives you a count-in.
Slowing down. The speed slider runs from 25 to 200 percent. Here, speed and pitch move together, like a record played slower, so 50 percent is an octave lower. That is often fine for picking out rhythms and fast notes. When you need the pitch to stay put — to play along in tune — use the audio player with speed control, which keeps pitch as it changes tempo.
Practice routine. A common approach is to start at a speed you can play cleanly, say 60 or 70 percent, repeat until it is consistent, then step up by 5 or 10 percent. The repeat counter makes it easy to hold yourself to, say, ten clean passes per step.
Formats. Anything your browser can decode works: WAV, MP3, M4A and usually OGG and FLAC.
FAQ
Why does the pitch drop when I slow it down?
This player changes the playback rate of the audio directly, which shifts pitch and speed together, as a turntable does. For slowing down without the pitch changing, use the audio player with speed control, which uses the browser's pitch-preserving time stretch.
Is there a gap when the loop jumps back?
No. The loop points are applied by the Web Audio engine to the decoded samples, so the jump from B to A happens on the exact sample. If you hear a click, the waveform is not at zero at one of the points; moving A or B by a few hundredths of a second usually clears it.
Is my audio uploaded anywhere?
No. The file is read and decoded by your browser on your own device, and playback happens there too. Nothing is sent to a server, so it works with private recordings and keeps working offline once the page has loaded.
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