Patent ID: 7378586

Claim:
A tone generation apparatus comprising: a memory capable of storing n bits data per address, said memory storing a plurality of compressed waveform data segmented into a plurality of frames, wherein a number of bits per sample of the compressed waveform data is variable between the frames, but uniform within each of the frames, each of the frames of the compressed waveform data is stored over a predetermined number j of successive addresses of said memory, and each of the frames includes, in a predetermined layout, an auxiliary information area for storing auxiliary information that includes compression-related information to be used for decompressing the compressed waveform data, and a data area for storing a plurality of samples of the compressed waveform data of the frame, wherein irrespective of the number of bits per sample of compressed waveform data stored in said data area of each frame, each frame is stored over said predetermined number j of successive addresses, wherein said auxiliary information area and data area in each frame are fixed in position irrespective of the number of bits per sample of compressed waveform data stored in the frame, and wherein said compression-related information includes number-of-bits information indicative of said number of bits per sample within the corresponding one of the frames; an address generation section that generates, every sampling cycle, a readout address varying at a predetermined rate corresponding to a designated tone pitch; a readout section that designates, on the basis of said readout address, any one of the frames to be read out and reads out stored data of the designated frame from said memory address by address; an auxiliary information retrieval section that, of the data of the frame read out by said readout section, retrieves the auxiliary information from the auxiliary information area; a compressed waveform data retrieval section that, of the data of the frame read out by said readout section, retrieves the samples of the compressed waveform data from the data area in accordance with the number of bits per sample designated by said number-of-bits information included in the auxiliary information retrieved by said auxiliary information retrieval section; a decoding section that decompresses each of the samples of the compressed waveform data retrieved by said compressed waveform data retrieval section; and a tone generation section that generates a tone on the basis of the waveform data decompressed by said decoding section.