Grain start position and duration together determine which region of a sample buffer each grain plays back

In a sampling granular synthesizer, each grain reads a specific segment of a loaded audio buffer. Two parameters jointly define this segment: Start position (in samples or milliseconds from the buffer start) — sets where in the sample the grain begins. Duration — sets how many samples the grain plays. Playback rate (pitch) scales the relationship between time and sample position. Because the line object steps from a start sample to an end sample over the grain duration, the actual end sample is start + (duration × rate). When rate = 1, grain duration in time equals grain duration in samples. Boundaries must be enforced: a start position beyond the buffer length is impossible and must be clamped.

Examples

Grain start = 2000 ms, duration = 100 ms, rate = 1: the grain plays samples from 2000ms to 2100ms. Rate = 0.5: same grain sounds pitched down an octave and plays twice as slowly.

Assessment

A grain generator has buffer length 5000ms, grain start = 4900ms, grain duration = 200ms, rate = 1. Predict what happens at the end of the grain and what constraint should be enforced to prevent it.