PlayBuf plays a Buffer at a controllable rate, with optional looping and a trigger to jump to startPos

PlayBuf reads through a Buffer automatically according to a playback rate argument. The rate is a ratio: 1 = normal speed, 2 = double speed, -1 = reverse. The numChannels argument must match the buffer’s channel count — a mismatch silently produces wrong output. Use BufRateScale.kr(buf) to compensate for differing buffer and server sample rates. Loop=1 makes PlayBuf loop and ignore doneAction. A t_trig argument allows jumping back to startPos. PlayBuf’s doneAction defaults to 0, which leaves finished Synths consuming CPU — specify doneAction:2 for one-shot sounds.

Examples

sig = PlayBuf.ar(2, buf, BufRateScale.kr(buf) * rate, t_trig, start, loop, doneAction:da); Transpose by semitones: \rate, 7.midiratio (a perfect fifth up).

Assessment

A student loads a stereo buffer and uses PlayBuf.ar(1, buf). The sound plays in mono only and sounds pitched down. Identify both bugs and fix them.