Question

I am trying to create a audio meter level while I am recording the user voice using avaudiorecorder. Can someone help me in that regard?

Answer 1

Actually, the code is pretty straightforward since AVAudioPlayer and AVAudioRecorder have built in methods to get you on your way. My approach was this:

• make a repeating call to -updateMeters and the averagePowerForChannel: & peakPowerForChannel: methods and call a delegate method to notify the controlling object

Example:

NSOperationQueue *queue=[[NSOperationQueue alloc] init];
NSInvocationOperation *operation=[[NSInvocationOperation alloc] initWithTarget:self selector:@selector(updateMeter) object:nil];
[queue addOperation: operation];

and

-(void)updateMeter
{
  do {
      //don't forget:
      [recorder updateMeters];
       self.averagePower   = [recorder averagePowerForChannel:0];
       self.peakPower      = [recorder peakPowerForChannel:0];

       // we don't want to surprise a ViewController with a method call
       // not in the main thread
      [self.delegate performSelectorOnMainThread: @selector(meterLevelsDidUpdate:) withObject:self waitUntilDone:NO];
      [NSThread sleepForTimeInterval:.05]; // 20 FPS
     }while(someCondition);
}

If your View Controller implements the meterLevelsDidUpdate: method, you can use this method to update your Level Meter.

• create a UIView subclass with a subview that changes its height according to the average or peak value(s). Adjust to taste.