Band Mate Easy Perc
Band Mate
A percussion app you play by tapping the screen or moving your device. Play one instrument right away, or a kit that combines several.
- Platforms
- iOS · Android
- Built with
- Swift / SwiftUI · C audio mixer · CoreMotion
- Pricing
- Free · no ads · offline
- Languages
- English · 한국어 · 日本語
Hand percussion is one of the quickest ways to add feel to a song, yet few people have a cowbell, a pair of congas and a tambourine within reach. Easy Perc puts ten instruments on the phone and lets you play them the way you would play the real thing: tapping with several fingers, or striking and shaking the device itself. You can start on one instrument at once, or combine several into a kit.
What it does
- Ten instrumentsCowbell, tambourine, bongo, shaker, conga, claves, woodblock, triangle, hand clap and hi-hat. The sample changes with playing strength.
- Tap playMulti-touch pads fill the screen.
- Motion playStrike or shake the device. Sensitivity and soft/strong thresholds are set with knobs.
- Custom kitsCombine instruments into pads, set volume per pad, and drag dividers to resize them.
- MetronomeA built-in metronome with tactile knob controls.
- iPhone and iPadAdaptive layouts for both, offline, no account.
- Sampled soundOver 100 recorded samples, so the sound changes with how hard you play.
- Offline and privateNo ads, no account; your kits are stored on the device.
Design choices
Strength changes the sound
Each of the ten instruments has several recorded layers, and the one that plays depends on how hard you hit. A soft tap and a strong hit are different samples, not the same sound at two volumes, which is what makes a shaker or a hi-hat feel played.
Motion play with knobs, not guesswork
Motion sensing differs by hand and by phone, so instead of hiding a fixed threshold the app exposes it. Each instrument has knobs for motion sensitivity, and the tambourine adds a soft and strong threshold, the bongo and conga a low and high one.
Shake and touch together
In the tambourine's shake mode the screen still accepts touches. Motion plays the shake sample and a touch plays the pad sample, and neither cuts the other off. Touch haptics are switched off during motion so the phone's own buzz is not read as another hit.
Kits you shape by hand
A kit combines instruments into pads. Each pad has its own volume, and a long-press opens the layout so you can drag the dividers to resize pads. A built-in metronome with tactile knobs keeps time, and saved kits stay on the device.
How it's built
A C mixer tested under sanitizers
The audio engine is a portable C mixer with no allocation or locks on the render thread. The test script compiles it with warnings as errors under AddressSanitizer and UndefinedBehaviorSanitizer, and exercises simultaneous hits, voice limits, choke, metronome and output stability.
Telling a wrist arc from a strike
CoreMotion is sampled at 100 Hz. A wrist swing is detected from angular velocity, and while rotation is active the linear stop detector is reset, because the acceleration of an arc would otherwise create a second, delayed hit. After a gap of more than 0.25 s the detector state restarts.
Samples checked as files
At the 1.1.3 baseline the app ships 149 WAV samples per platform. An asset script checks their references and format, and a separate test checks that the sample dynamics behave as designed. The audio session asks for a 5 ms I/O buffer to keep touch-to-sound delay short.
Native on both platforms
iOS is Swift and SwiftUI with CoreMotion; Android is a separate native project with a C++ AAudio bridge, built with the NDK. Saved kits are protected by tests for restore, duplicate, cancelled delete, corrupt source preservation and rejection of invalid data.
