handle->real_timestamp_begin = fmt->timestamp_begin(td, handle, BT_CLOCK_REAL);
handle->real_timestamp_end = fmt->timestamp_end(td, handle, BT_CLOCK_REAL);
handle->real_timestamp_begin = fmt->timestamp_begin(td, handle, BT_CLOCK_REAL);
handle->real_timestamp_end = fmt->timestamp_end(td, handle, BT_CLOCK_REAL);