说明：  ADPCM(Adaptive Differential Pulse Code Modulation)，是一种针对 16bits( 或8bits或者更高) 声音波形数据的一种有损压缩算法,它将声音流中每次采样的 16bit 数据以 4bit 存储,所以压缩比 1:4. 而且压缩/解压缩算法非常简单,所以是一种低空间消耗，高质量高效率声音获得的好途径。保存声音的数据文件后缀名为 .AUD 的大多用ADPCM 压缩。
(ADPCM (Adaptive Differential Pulse Code Modulation), is a response to 16bits (or 8 bits or higher) voice waveform data of a lossy compression algorithm, it will sound each stream sampling 16bit data to 4bit storage, so the compression ratio 1:4. and compression/decompression algorithm is very simple, there is a low space consumption, high-quality sound and efficient way to get good. Preservation of the voice data file is named suffix. AUD mostly using ADPCM compression.)