Go: Use the SoundTouch Library in iOS to make a voice changer

http://yarin.blog.51cto.com/1130898/640398

First download SoundTouch open Source Library, you can go to the official website to find, http://www.surina.net/soundtouch/.

Here are a few of the main adjustments we want to make to modify the audio file:

  
 

   
  

  
msoundtouch.setsamplerate (samplerate); //Set the sampling frequency of the sound  
   
  

  
Msoundtouch.setchannels (Channels); //Set the sound channel  
   
  

  
M_soundtouch.settempochange (Tempodelta); //This is the legendary change of speed does not change the tone  
   
  

  
M_soundtouch.setpitchsemitones (Pitchdelta); //Set pitch of sound  
   
  

  
Msoundtouch.setratechange (Ratedelta); //Set the rate of sound  
   
  

  
//Quick is a bool variable, use_quickseek specific what to use I am not very clear for the time being.  
   
  

  
Msoundtouch.setsetting (Setting_use_quickseek, quick);
   
  

  
//Noantialias is a bool variable, use_aa_filter specific what to use I'm not quite sure yet.  
   
  

  
Msoundtouch.setsetting (Setting_use_aa_filter,!) ( Noantialias));

  
 

The last two issues to note:

Has started my compilation, the sound is very strange also has the noise very big, still spent a lot of time to find the reason, but all did not have the result, suddenly remembered that we said, it also supports 32-bit floating point and 16-bit fixed point, by default, 32-bit floating point, I will change it to 16-bit fixed point number, haha Change the way you find the Float_samples macro in the STTypes.h file, comment it out, and open the Integer_samples macro, as follows:

  
 

   
  

  
#if! (Integer_samples | | Float_samples)  
   
  

  

   
  

  
// Choose either 32bit floating point or 16bit integer sampletype  
   
  

  
/// by choosing one of the following defines, unless this selection  
   
  

  
//has already been do in some other file.  
   
  

  
////  
   
  

  
//Notes:  
   
  

  
//-in Windows environment, choose the sample format with the  
   
  

  
/// following defines.  
   
  

  
//-in GNU environment, the floating point samples is used by  
   
  

  
/// default, but integer samples can is chosen by giving the  
   
  

  
//Following switch to the Configure script:  
   
  

  
/// ./configure--enable-integer-samples  
   
  

  
/// However, if you still prefer to select the sample format here  
   
  

  
// also in GNU environment, then #undef the Integer_sample  
   
  

  
///Float_sample defines first as in comments above.  
   
  

  
#define Integer_samples 1//< 16bit INTEGER SAMPLES  
   
  

  
//#define Float_samples 1//< 32bit FLOAT SAMPLES  
   
  

  

   
  

  
#endif  
  
 

Another problem is that the test on the simulator is completely correct, this time put on the real machine equipment, direct error, quit the program, another time spent me a lot of problems, and finally found that in the real machine needs to change the channel to Mono, as below, in their own settings when used:

 
   
  

  
    
   
Msoundtouch.setchannels (2); //1 is mono  
 
   
  

It's done, of course. If you want to continue to understand the SoundTouch library, then here (http://blog.csdn.net/leilu2008/article/details/6540575) a series of reference materials.