计划在新版本的“语音合成助手”（iphone上appstore中可以下载这款软件）中加入混音技术，目前正在调研这方面的知识，现转载一篇文章，以备查看。
Step 1,
Get the Raw data of the two files, (Example,of the sample 8bit and 8Kh, means one sample is of
8bit)
Step 2
Let the two audio signal be A and Brespectively, the range is between 0 and 255. Where A and B are the
Sample Values (Each raw data) And store theresultant into the Y
If Both the samples Values are possitve
Y = A + B - A * B /255
Where Y is the resultant signal whichcontains both signal A and B, merging two audio streams into single
stream by this method solves the problem ofoverflow and information loss to an extent.
If the range of 8-bit sampling is between-127 to 128
If both A and B are negative Y = A +B - (A * B /(-127))
Else Y = A + B - A * B / 128
Similarly for the nbit (ex 16bit data)
For n-bit sampling audio signal
If both A and B are negative Y = A + B - (A * B /(-(2 pow(n-1) -1)))
Else Y = A + B - (A * B / (2 pow(n-1))
Step 3.
Add the Header to the Resultant (mixed) dataand play back.
If some thing is unclear and ambigious letme know.
Regards
Ranjeet Gupta.
还有简单C程序示意代码，但是其中包含了核心算法：
#include
#include
#include
#include
int main(int argc,char *argv[]) {
char mixname[255];
FILE *pcm1, *pcm2, *mix;
char sample1, sample2;
int value;
pcm1 = fopen(argv[1],"r");
pcm2 = fopen(argv[2],"r");
strcpy (mixname, argv[1]);
strcat (mixname, "_temp.wav");
mix = fopen(mixname, "w");
while(!feof(pcm1)) {
sample1 = fgetc(pcm1);
sample2 = fgetc(pcm2);
if ((sample1 < 0) && (sample2< 0)) {
value = sample1 + sample2 - (sample1 *sample2 / -(pow(2,16-1)-1));
}else{
value = sample1 + sample2 - (sample1 *sample2 / (pow(2,16-1)-1));
}
fputc(value, mix);
}
fclose(pcm1);
fclose(pcm2);
fclose(mix);
return 0;
}
