Method of and device for compressing and reproducing waveform data

A musical tone generating device comprising:

• means for acquiring waveform data, said waveform data to be used as a musical sound source and said waveform data comprising a plurality of data items, each having plural bits;
• weight coefficient providing means;
• reduction operation means for inputting waveform data to be compressed and performing an operation for reducing a value of the waveform data in accordance with a weight coefficient provided by the weight coefficient providing means;
• coefficient generation means for producing a filter coefficient;
• compression filter means for inputting waveform data provided by the reduction operation means and inputting the filter coefficient produced by the coefficient generation means and performing a data compression processing on the waveform data using a linear prediction method;
• and
• memory means for storing waveform data on which the data compression processing and the data reduction processing have been performed.

A waveform data compression device comprising:

• means for acquiring waveform data, said waveform data to be used as a musical sound source wherein said waveform data comprising a plurality of data items, each of said data items having plural bits;
• coefficient generation means for producing a filter coefficient;
• compression filter means for inputting waveform data to be compressed and performing a data compression processing on the waveform data by a linear prediction method utilizing the filter coefficient;
• weight coefficient providing means;
• reduction operation means for performing an operation for reducing a value of waveform data provided by the compression filter means in accordance with a weight coefficient provided by the weight coefficient providing means;
• memory means for storing waveform data on which the data compression processing and the data reduction processing have been performed.

A method for compressing musical waveform data for use in a music processing apparatus comprising:

• providing digital waveform sample data comprising plural data items each of which comprises plural bits;
• dividing the waveform sample data into plural sections each of the sections comprising plural data items;
• detecting a maximum effective number of bits in any one data item for each of the sections;
• and
• adjusting the bit number of waveform sample data from the providing step in such a manner that the maximum number of bits in each of the data items in any section is no more than the maximum effective number of bits detected for the data items in that section;
• and
• storing the adjusted waveform sample data in memory means.

A method for compressing digital musical waveform data for use in a music processing apparatus comprising:

• providing digital waveform sample data comprising plural data items each of which comprises plural bits;
• dividing the waveform sample data into plural block sections each of the sections comprising plural data items;
• performing a data compression processing for each of the block sections to produce compressed waveform data;
• dividing the compressed waveform sample data of each of the block sections into plural frame sections each comprising plural data items;
• detecting a maximum effective number of bits in any one data item for each of the frame sections;
• and
• adjusting the compressed waveform sample data in such a manner that the maximum number of bits in each of the data items in any frame section is no more than the maximum effective number of bits detected for the data items in that frame section;
• and
• storing the adjusted waveform sample data in a memory means.

A method for compressing digital data for a tone control comprising:

• a first step for providing digital data said digital data comprising plural data items each of which comprises plural bits;
• a second step for dividing the digital data into plural sections each comprising plural data items and for detecting a maximum value of effective bit number of the digital data for each of the sections;
• and
• a third step for adjusting the digital data provided by the first step in such a manner that the digital data for each of the sections has a bit number corresponding to the maximum value which has been detected for each of the sections in the second step and for storing the adjusted digital data in memory means.

A musical tone generating apparatus comprising:

• inputting means for receiving waveform data to be recorded;
• filter coefficient providing means for providing a filter coefficient corresponding to the waveform data;
• compression filter means for receiving said waveform data and said filter coefficient and for performing a data compression processing on said waveform data in accordance with said filter coefficient to generate compressed waveform data items having less than the fixed number of bits;
• a waveform memory for storing data of a fixed number of bits per memory address;
• and
• recording means for recording the compressed waveform data items into said waveform memory in a packed fashion in which some data items are recorded in memory areas spanning plural memory addresses.

A musical tone generating apparatus comprising:

• providing means for providing waveform data to be recorded;
• filter coefficient providing means for providing a filter coefficient corresponding to the waveform data;
• compression filter means comprising:
• receiving means for receiving said waveform data and said filter coefficient;
• compression means for performing a data compression processing on said waveform data in accordance with said filter coefficient and for generating compressed waveform data, wherein said compressed waveform data comprises a plurality of blocks wherein each of said blocks comprises a plurality of frames and wherein each of said frames has an associated shortening bit number;
• a waveform memory for storing waveform data of a fixed number of bits;
• and
• recording means for recording the compressed waveform data into said waveform memory comprising:
• means for recording in said waveform memory each of said blocks in series and each of said frames in series;
• means for recording in said waveform memory the shortening bit number for at least one of said frames intermixed with the preceding frame.

A digital musical tone generating apparatus comprising:

• means for generating bit-shortened compressed waveform data;
• a waveform memory for storing said bit-shortened compressed waveform data;
• reading means comprising:
• retrieving means for retrieving said bit-shortened compressed waveform data from said waveform memory;
• extending means for generating extended waveform data of a predetermined bit length wherein said extending means comprises means for expanding the bit-length of said waveform data to said predetermined bit length;
• coefficient providing means for providing a demodulation filter coefficient;
• and
• demodulation filter means comprising:
• receiving means for receiving said extended waveform data and said demodulation coefficient;
• demodulation means for performing a data demodulation on said extended waveform data in accordance with said demodulation coefficient and for generating reproduced waveform data;
• and
• output means for outputting said reproduced waveform data.

A digital musical tone generating apparatus comprising:

• means for generating bit-shortened compressed waveform data;
• a waveform memory for storing said bit-shortened compressed waveform data;
• reading means for retrieving said bit-shortened compressed waveform data from said waveform memory;
• coefficient providing means for providing a demodulation filter coefficient and a bit-value coefficient;
• demodulation means for performing data demodulation processing on said waveform data in accordance with said demodulation coefficient.