Two index positions
INDEX01 marks the normal start of a track. INDEX00 marks a preceding in-file gap when present. A timestamp is minutes:seconds:CD frames, with 75 frames per second; it is not an audio sample number.
Choose intentionally
Appending gaps to previous tracks preserves the conventional playback boundary at INDEX01. Prepending uses INDEX00 for the next track. Discarding removes that interval. Leading audio before the first selected start is excluded, so inspect hidden-track material separately.
Generated PREGAP and POSTGAP instructions request silence that is not in the file. This version rejects those instructions instead of silently inventing or dropping audio.
Work through a two-track boundary
Imagine track 2 has INDEX00 at 00:01:00 and INDEX01 at 00:01:15. The gap is 15CD frames, or 0.20 seconds. At 44,100 Hz, those positions are 44,100 and 52,920 audio sample frames. Previous-gap handling ends track 1 at 52,920 and starts track 2 there. Next-gap handling instead joins the tracks at 44,100. Discard leaves track 1 ending at 44,100 and track 2 beginning at 52,920.
Check the exported ledger’s startFrame and endFrame columns rather than estimating the cut from a rounded duration. End frames are exclusive: a segment from 0 to 44,100 contains exactly 44,100 sample frames. A stereo frame contains one sample from each channel, so the frame count is not the number of interleaved scalar samples.
Listen around the decision
Audition a few seconds before and after the join with gapless playback enabled in your player. Silence, audience noise and spoken introductions may be intentionally assigned to either track. A CUE file describes boundaries, not artistic intent. Keep the original album when the choice is uncertain, especially if material precedes the first INDEX01.