A waveform data structure includes a plurality of types of frames having different data sizes. Each of the plurality of types of frames includes an auxiliary information area and a data area. The auxiliary information area includes an area for storing common effective-bit length data for a section of waveform samples, and an area for storing an identifier for identifying one of the plurality of types of frames. The data area is an area for storing extracted waveform samples which are extracted from the waveform samples based on the common effective-bit length. The number of the extracted waveform samples is determined based on the common effective-bit length.