title: what values should i calculate from FFT of two audio file and compare it to show them they are equal?
body: <p>I want to compare  two audio files(voice recording) and find whether they are identical or not (to some extent).I have come up with FFT(OouraFFT).I have integrated code and gave my  audio file as input  and "calculateWelchPeriodogramWithNewSignalSegment" is called.There is a term spectrum data used in "calculateWelchPeriodogramWithNewSignalSegment" method.now what should i use to compare two audio files.please anyone explain the concept for using FFT to compare two audio signal(speach signal).Further what should i proceed with?Any valuable information will be more helpful.Thanks in Advance.</p>
  
  <p>EDIT:</p>
  
  <pre><code> MyAudioFile  *audioFile = [[MyAudioFile alloc]init];
  OSStatus result = [audioFile open:var ofType:@"wav"];
  int numFrequencies=16384;
  int kNumFFTWindows=10;
  
  OouraFFT *myFFT = [[OouraFFT alloc] initForSignalsOfLength:numFrequencies*2 andNumWindows:kNumFFTWindows];
  for(long i=0; i&lt;myFFT.dataLength; i++)
  {
      myFFT.inputData[i] = (double)audioFile.audioData[i];
  } 
  [myFFT calculateWelchPeriodogramWithNewSignalSegment];
  NSLog(@"the spectrum data 1 is  %f ",myFFT.spectrumData[1]);
  NSLog(@"the spectrum data 2 is  %f",myFFT.spectrumData[2]);
      NSLog(@"the spectrum data 8192 is  %f ",myFFT.spectrumData[8192]);
  </code></pre>
  
  <p>I have created MyAudioFile class which contains</p>
  
  <pre><code>-(OSStatus)open:(NSString *)fileName ofType:(NSString *)fileType{
  OSStatus result = -1;
  
  CFStringRef filePath=fileName;
  
  CFURLRef audioFileURL = CFURLCreateWithFileSystemPath(kCFAllocatorDefault, (CFStringRef)filePath, kCFURLPOSIXPathStyle, false);
  //open audio file
  result = AudioFileOpenURL (audioFileURL, kAudioFileReadPermission, 0, &amp;mAudioFile);
  if (result == noErr) {
      //get  format info
      UInt32 size = sizeof(mASBD);
  
      result = AudioFileGetProperty(mAudioFile, kAudioFilePropertyDataFormat, &amp;size, &amp;mASBD);
  
      UInt32 dataSize = sizeof packetCount;
      result = AudioFileGetProperty(mAudioFile, kAudioFilePropertyAudioDataPacketCount, &amp;dataSize, &amp;packetCount);
      NSLog([NSString stringWithFormat:@"File Opened, packet Count: %d", packetCount]);
  
      UInt32 packetsRead = packetCount;
      UInt32 numBytesRead = -1;
      if (packetCount &gt; 0) { 
          //allocate  buffer
          audioData = (SInt16*)malloc( 2 *packetCount);
          //read the packets
          result = AudioFileReadPackets (mAudioFile, false, &amp;numBytesRead, NULL, 0, &amp;packetsRead,  audioData); 
          NSLog([NSString stringWithFormat:@"Read %d  bytes,  %d packets", numBytesRead, packetsRead]);
      }
  }
  else
      NSLog([NSString stringWithFormat:@"Could not open file: %@", filePath]);
  
  
  CFRelease (audioFileURL);     
  return result;
  }
  </code></pre>
  
  <p>I think ,now i am  done with FFT , myFFT.spectrumData[i] has the sampled output differnt values of i.</p>
  
  <p>Do i want now to stop this and integrate Accelerate framework for doing FFT.I am confused.Please tell me which one to use?</p>