A method of cross-fading or cutting between a first audio section and a second destination audio section, the first audio section and the second destination audio section each containing an onset associated with an anacrusis that is related to a selected abstract exit point or abstract entry point in an audio track and where each anacrusis is a note or sequence of notes that precedes the first downbeat in a bar of music in each audio section, the method comprising: in the first audio section and the second destination audio section selecting anacruses that are possible actual exit points and possible actual entry points and which have corresponding measured displacements in time to abstract exit and abstract entry points respectively in the first audio section and the second destination audio section; aligning said selected anacruses in the first audio section and the second destination audio section so that they occur at a common point in time; measuring time differences of onsets in each of the first audio section and the second destination audio section from the selected anacruses to create alternative cross-fade or cut positions for transitions between the first audio section and the second destination audio section; assessing which respective cross-fade or cut position in the first audio section and the second destination audio section occurs earliest in time with respect to the aligned anacruses and selecting the earliest cross-fade or cur position, the earliest cross-fade or cut position having and associated onset; and producing a cross-fade or cut between the first audio section and the second destination audio section at a point at or before said associated onset starts to rise, such that the second destination audio section replaces the first audio section as an active audio output to realize a seamless rhythmic transition in audio output by preserving integrity of musical timing between the first audio section and the second destination audio section. in the first audio section and the second destination audio section selecting anacruses that are possible actual exit points and possible actual entry points and which have corresponding measured displacements in time to abstract exit and abstract entry points respectively in the first audio section and the second destination audio section; aligning said selected anacruses in the first audio section and the second destination audio section so that they occur at a common point in time; measuring time differences of onsets in each of the first audio section and the second destination audio section from the selected anacruses to create alternative cross-fade or cut positions for transitions between the first audio section and the second destination audio section; assessing which respective cross-fade or cut position in the first audio section and the second destination audio section occurs earliest in time with respect to the aligned anacruses and selecting the earliest cross-fade or cur position, the earliest cross-fade or cut position having and associated onset; and producing a cross-fade or cut between the first audio section and the second destination audio section at a point at or before said associated onset starts to rise, such that the second destination audio section replaces the first audio section as an active audio output to realize a seamless rhythmic transition in audio output by preserving integrity of musical timing between the first audio section and the second destination audio section.