Methods of efficiently recording an audio signal in semiconductor memory

A method of recording an audio signal in a semiconductor memory, comprising the steps of:

• (a) digitizing an audio signal to generate digitized audio data;
• (b) encoding said digitized audio data to generate a plurality of successive hierarchical levels of data corresponding to an audible portion of the audio signal including a lowest hierarchical level of data for reproduction of the audio signal with relatively low fidelity, and including at least one other higher hierarchical level of data, each successive higher hierarchical level representing additional data for successively relatively greater fidelity;
• (c) storing all of said hierarchical encoded levels of data in a buffer memory;
• (d) copying, from said buffer memory to said semiconductor memory, as many of said stored hierarchical levels of data as said semiconductor memory can store;
• and
• (e) recording in said semiconductor memory, a code indicative of a number of hierarchical levels of data copied in step (d).

An apparatus for recording an audio signal in a semiconductor memory and for reproducing the audio signal, comprising:

• an analog-to-digital converter for converting said audio signal to first digitized audio data;
• a hierarchical encoder, for encoding said first digitized audio data to generate a plurality of successive hierarchical levels of data corresponding to an audible portion of the audio data including a lowest hierarchical level of data for reproduction of the audio signal with relatively low fidelity, and including at least one other higher hierarchical level of data, each successive higher hierarchical level representing additional data for successively relatively greater fidelity, and for writing said hierarchical levels of data into said semiconductor memory;
• a memory address generator coupled to said hierarchical encoder, for generating memory addresses so that, upon determining that said semiconductor memory has reached maximum storage capacity, recording can continue by overwriting a highest hierarchical level of data previously recorded in said semiconductor memory with new data of hierarchical levels lower than the overwritten highest hierarchical level;
• a hierarchy code generator coupled to said memory address generator, for recording in said semiconductor memory, a code indicative of a number of hierarchical levels of data currently recorded therein;
• a hierarchy code reader coupled to said semiconductor memory, for reading said recorded code;
• a hierarchical decoder coupled to said semiconductor memory, for reading a number of hierarchical levels of data designated by said code and for decoding the read data to generate second digitized audio data;
• and
• a digital-to-analog converter coupled to receive said second digitized audio data from said hierarchical decoder, for converting said second digitized audio data to an audio signal.

An apparatus for recording an audio signal in a semiconductor memory, comprising:

• an analog-to-digital converter for converting said audio signal to digitized audio data;
• a hierarchical encoder, for encoding said digitized audio data to generate a plurality of successive hierarchical levels of data corresponding to an audible portion of the audio signal including a lowest hierarchical level of data for reproduction of the audio signal with relatively low fidelity, and including at least one other higher hierarchical level of data, each successive higher hierarchical level representing additional data for successively relatively greater fidelity;
• a buffer memory coupled to said hierarchical encoder, for storing the hierarchical levels of data generated by said hierarchical encoder;
• a memory address generator coupled to said buffer memory, for generating memory addresses at which said hierarchical levels of data are stored;
• a data size calculator coupled to said memory address generator, for calculating an amount of data stored in said buffer memory;
• a hierarchical level selector coupled to said data size calculator, for determining a number of hierarchical levels of data capable of being stored in said semiconductor memory, and for copying the number of hierarchical levels of data thus determined from said buffer memory to said semiconductor memory;
• and
• a hierarchy code generator coupled to said hierarchical level selector, for recording in said semiconductor memory a code indicative of a number of hierarchical levels of data recorded therein.