最近做了个关于单片机播放语音的ADPCM编解码在STC15F408上实现，
ADPCM编码子程序，可直接移植使用，已经测试OK。
Matlab源程序如下:
- function adpcm_y = adpcm_encoder(raw_y)
- % ADPCM编码子程序
- % Edit by L7
- IndexTable = [-1, -1, -1, -1, 2, 4, 6, 8, -1, -1, -1, -1, 2, 4, 6, 8];
-
- StepSizeTable = [7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767];
- prevsample = 0;
- previndex = 1;
- Ns = length(raw_y);
- n = 1;
- raw_y = 32767 * raw_y; % 16-bit operation
- while (n <= Ns)
- predsample = prevsample;
- index = previndex;
- step = StepSizeTable(index);
- diff = raw_y(n) - predsample;
- if (diff >= 0)
- code = 0;
- else
- code = 8;
- diff = -diff;
- end
- tempstep = step;
- if (diff >= tempstep)
- code = bitor(code, 4);
- diff = diff - tempstep;
- end
- tempstep = bitshift(tempstep, -1);
- if (diff >= tempstep)
- code = bitor(code, 2);
- diff = diff - tempstep;
- end
- tempstep = bitshift(tempstep, -1);
- if (diff >= tempstep)
- code = bitor(code, 1);
- end
- diffq = bitshift(step, -3);
- if (bitand(code, 4))
- diffq = diffq + step;
- end
- if (bitand(code, 2))
- diffq = diffq + bitshift(step, -1);
- end
- if (bitand(code, 1))
- diffq = diffq + bitshift(step, -2);
- end
- if (bitand(code, 8))
- predsample = predsample - diffq;
- else
- predsample = predsample + diffq;
- end
- if (predsample > 32767)
- predsample = 32767;
- elseif (predsample < -32768)
- predsample = -32768;
- end
- index = index + IndexTable(code+1);
- if (index < 1)
- index = 1;
- end
- if (index > 89)
- index = 89;
- end
- prevsample = predsample;
- previndex = index;
- adpcm_y(n) = bitand(code, 15);
- %adpcm_y(n) = code;
- n = n + 1;
- end
所有资料51hei提供下载:
ADPCM.rar
(409.27 KB, 下载次数: 33)
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