No Decode Step
MP3 frames are self-describing, so their boundaries are found directly from the byte stream — no ffmpeg, no subprocess, no decode/re-encode round trip.
Byte-Identical Output
Cuts are made by byte-copying whole frames from the source file. Output is bit-identical to the original, just shorter.
Continuously Verified
Duration parsing is cross-validated against mutagen's independent implementation to the millisecond, and fuzzed continuously with ClusterFuzzLite.