BeatsSamplesConverter converter(smfs->session().tempo_map(), pos);
smfs->update_length(pos + converter.to(length_beats.round_up_to_beat()));
smfs->mark_streaming_write_completed (source_lock);
BeatsSamplesConverter converter(smfs->session().tempo_map(), pos);
smfs->update_length(pos + converter.to(length_beats.round_up_to_beat()));
smfs->mark_streaming_write_completed (source_lock);