サウンドレコーディングソースを確認する方法

Question

iPadアプリでサウンドを録音するとき、サウンドのソースが内蔵マイクまたはヘッドホンマイクからのものかどうかをどのように知ることができますか？

追加情報：iOS ver 4.2以上。

Answer 1

これを判断する方法は、ハードウェアをポーリングして、現在のオーディオルートを照会することです。

AudioSessionGetPropertyオブジェクトを使用して、オーディオのルートを取得します。

このexample by @TPoschelは適切なトラックに設定する必要があります。

- (void)playSound:(id) sender 
{ 
    if(player){ 

     CFStringRef route; 
     UInt32 propertySize = sizeof(CFStringRef); 
     AudioSessionInitialize(NULL, NULL, NULL, NULL); 
     AudioSessionGetProperty(kAudioSessionProperty_AudioRoute, &propertySize, &route); 

     if((route == NULL) || (CFStringGetLength(route) == 0)){ 
      // Silent Mode 
      NSLog(@"AudioRoute: SILENT"); 
     } else { 
      NSString* routeStr = (NSString*)route; 
      NSLog(@"AudioRoute: %@", routeStr); 

      /* Known values of route: 
      * "Headset" 
      * "Headphone" 
      * "Speaker" 
      * "SpeakerAndMicrophone" 
      * "HeadphonesAndMicrophone" 
      * "HeadsetInOut" 
      * "ReceiverAndMicrophone" 
      * "Lineout" 
      */ 

      NSRange headphoneRange = [routeStr rangeOfString : @"Headphone"]; 
      NSRange headsetRange = [routeStr rangeOfString : @"Headset"]; 
      NSRange receiverRange = [routeStr rangeOfString : @"Receiver"]; 
      NSRange speakerRange = [routeStr rangeOfString : @"Speaker"]; 
      NSRange lineoutRange = [routeStr rangeOfString : @"Lineout"]; 

      if (headphoneRange.location != NSNotFound) { 
       // Don't change the route if the headphone is plugged in. 
      } else if(headsetRange.location != NSNotFound) { 
       // Don't change the route if the headset is plugged in. 
      } else if (receiverRange.location != NSNotFound) { 
       // Change to play on the speaker 
       UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker; 
       AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride); 
      } else if (speakerRange.location != NSNotFound) { 
       // Don't change the route if the speaker is currently playing. 
      } else if (lineoutRange.location != NSNotFound) { 
       // Don't change the route if the lineout is plugged in. 
      } else { 
       NSLog(@"Unknown audio route."); 
      } 
     } 

     [player play]; 
    } 
}