SLAA361A July   2007  – August 2018 MSP430F169 , MSP430F169 , MSP430FG4618 , MSP430FG4618

 

  1.   Speech and Sound Compression and Decompression With MSP430™ MCUs
    1.     Trademarks
    2. 1 Introduction
    3. 2 Compression and Decompression Algorithms
      1. 2.1 Differential Pulse Code Modulation (DPCM)
      2. 2.2 Adaptive Differential Pulse Code Modulation (ADPCM)
    4. 3 Signal Chain on Chip in MSP430 MCUs
      1. 3.1 MSP430F169 Signal-Chain-on-Chip Solution
      2. 3.2 MSP430FG4618 Signal-Chain-on-Chip Solution
    5. 4 Performance on the MSP430 MCUs
      1. 4.1 Using the Associated Code
    6. 5 References
  2.   Revision History

2 Compression and Decompression Algorithms

The simplest way to make a voice recorder is to store the analog-to-digital conversion results (for example, 12-bit samples) directly in the flash memory. Most of the time, the audio data does not use the complete ADC range, which means that redundant information is stored in the flash memory. Compression algorithms remove this redundant information and reduce the data that must be stored.

Adaptive differential pulse code modulation (ADPCM) is a compression algorithm. Various ADPCM algorithms exist, all of which use differential codes and adaptation of the step-size of the quantizer. Section 2.1 describes differential pulse code modulation (DPCM), and Section 2.2 describes the IMA ADPCM algorithm, which is used in the associated code.