AN3143 datasheet(5/13 Pages) STMICROELECTRONICS

部件名	AN3143

功能描述	Audio software codec for the STM8S

PDF	13 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

标志

5 / 13 page

AN3143

ADPCM codec

Doc ID 17011 Rev 1

5/13

1.4

IMA ADPCM compression

The IMA ADPCM compression algorithm encoder calculates a difference (d) between a 16-

bit input linear sample (Sin) and a predicted linear sample (SL). The difference is quantized

to a 4-bit compressed output sample (Sq) by using an adapted quantization step (q). This

step is the same one as that used by the decoder. Figure 2 provides a flowchart of the

ADPCM encoder. It also shows the decoder building blocks with the functionality described

in Section 1.3 (see filled light green components). As the encoder covers identical blocks to

the decoder and produces identical results, there is no need to store prediction information.

The quantized difference is the only core information about the coded samples which needs

to be stored or transmitted.

Figure 2.

ADPCM encoder

AN3143 数据表(PDF) 5 Page - STMicroelectronics