将音频输出重定向到手机扬声器，将麦克风输入重定向到耳机

Question

是否可以将音频输出重定向到手机扬声器并仍然使用麦克风耳机输入？

如果我将音频路由重定向到手机扬声器而不是耳机，它也会重定向麦克风。这是有道理的，但我似乎不能只重定向麦克风输入？有什么想法吗？

这是我用来将音频重定向到扬声器的代码：

UInt32 doChangeDefaultRoute = true;        
propertySetError = AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryDefaultToSpeaker, sizeof(doChangeDefaultRoute), &doChangeDefaultRoute);
NSAssert(propertySetError == 0, @"Failed to set audio session property: OverrideCategoryDefaultToSpeaker");
UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride);

Answer 1

恐怕这不可能。

来自Audio Session Programming Guide - kAudioSessionProperty_OverrideAudioRoute

如果在您设置此属性的值时插入了耳机 到 kAudioSessionOverrideAudioRoute_Speaker，系统更改 输入和输出的音频路由：输入来自 内置麦克风；输出到内置扬声器。

this question 可能重复

Answer 2

这是可能的，但你如何设置它很挑剔。

[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];
UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
AudioSessionSetProperty(kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);

使用AVAudioSessionCategoryPlayAndRecord 非常重要，否则路由将无法到达扬声器。为音频会话设置覆盖路由后，您可以使用 AVAudioPlayer 实例并将一些输出发送到扬声器。

希望对其他人有用，就像对我一样。这方面的文档很分散，但 Skype 应用程序证明这是可能的。坚持下去，我的朋友们！ :)

这里有一些 Apple 文档：http://developer.apple.com/library/ios/#documentation/AudioToolbox/Reference/AudioSessionServicesReference/Reference/reference.html

在页面上搜索kAudioSessionProperty_OverrideAudioRoute

Answer 3

你可以做的是在任何情况下强制音频输出到扬声器：

来自UI Hacker - iOS: Force audio output to speakers while headphones are plugged in

@interface AudioRouter : NSObject

+ (void) initAudioSessionRouting;
+ (void) switchToDefaultHardware;
+ (void) forceOutputToBuiltInSpeakers;

@end

和

#import "AudioRouter.h"
#import <AudioToolbox/AudioToolbox.h>
#import <AVFoundation/AVFoundation.h>

@implementation AudioRouter

#define IS_DEBUGGING NO
#define IS_DEBUGGING_EXTRA_INFO NO

+ (void) initAudioSessionRouting {

    // Called once to route all audio through speakers, even if something's plugged into the headphone jack
    static BOOL audioSessionSetup = NO;
    if (audioSessionSetup == NO) {

        // set category to accept properties assigned below
        NSError *sessionError = nil;
        [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error: &sessionError];

        // Doubly force audio to come out of speaker
        UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
        AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);

        // fix issue with audio interrupting video recording - allow audio to mix on top of other media
        UInt32 doSetProperty = 1;
        AudioSessionSetProperty (kAudioSessionProperty_OverrideCategoryMixWithOthers, sizeof(doSetProperty), &doSetProperty);

        // set active
        [[AVAudioSession sharedInstance] setDelegate:self];
        [[AVAudioSession sharedInstance] setActive: YES error: nil];

        // add listener for audio input changes
        AudioSessionAddPropertyListener (kAudioSessionProperty_AudioRouteChange, onAudioRouteChange, nil );
        AudioSessionAddPropertyListener (kAudioSessionProperty_AudioInputAvailable, onAudioRouteChange, nil );

    }

    // Force audio to come out of speaker
    [[AVAudioSession sharedInstance] overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker error:nil];


    // set flag
    audioSessionSetup = YES;
}

+ (void) switchToDefaultHardware {
    // Remove forcing to built-in speaker
    UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_None;
    AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);
}

+ (void) forceOutputToBuiltInSpeakers {
    // Re-force audio to come out of speaker
    UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
    AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);


}

void onAudioRouteChange (void* clientData, AudioSessionPropertyID inID, UInt32 dataSize, const void* inData) {

    if( IS_DEBUGGING == YES ) {
        NSLog(@"==== Audio Harware Status ====");
        NSLog(@"Current Input:  %@", [AudioRouter getAudioSessionInput]);
        NSLog(@"Current Output: %@", [AudioRouter getAudioSessionOutput]);
        NSLog(@"Current hardware route: %@", [AudioRouter getAudioSessionRoute]);
        NSLog(@"==============================");
    }

    if( IS_DEBUGGING_EXTRA_INFO == YES ) {
        NSLog(@"==== Audio Harware Status (EXTENDED) ====");
        CFDictionaryRef dict = (CFDictionaryRef)inData;
        CFNumberRef reason = CFDictionaryGetValue(dict, kAudioSession_RouteChangeKey_Reason);
        CFDictionaryRef oldRoute = CFDictionaryGetValue(dict, kAudioSession_AudioRouteChangeKey_PreviousRouteDescription);
        CFDictionaryRef newRoute = CFDictionaryGetValue(dict, kAudioSession_AudioRouteChangeKey_CurrentRouteDescription);
        NSLog(@"Audio old route: %@", oldRoute);
        NSLog(@"Audio new route: %@", newRoute);
        NSLog(@"=========================================");
    }



}

+ (NSString*) getAudioSessionInput {
    UInt32 routeSize;
    AudioSessionGetPropertySize(kAudioSessionProperty_AudioRouteDescription, &routeSize);
    CFDictionaryRef desc; // this is the dictionary to contain descriptions

    // make the call to get the audio description and populate the desc dictionary
    AudioSessionGetProperty (kAudioSessionProperty_AudioRouteDescription, &routeSize, &desc);

    // the dictionary contains 2 keys, for input and output. Get output array
    CFArrayRef outputs = CFDictionaryGetValue(desc, kAudioSession_AudioRouteKey_Inputs);

    // the output array contains 1 element - a dictionary
    CFDictionaryRef diction = CFArrayGetValueAtIndex(outputs, 0);

    // get the output description from the dictionary
    CFStringRef input = CFDictionaryGetValue(diction, kAudioSession_AudioRouteKey_Type);
    return [NSString stringWithFormat:@"%@", input];
}

+ (NSString*) getAudioSessionOutput {
    UInt32 routeSize;
    AudioSessionGetPropertySize(kAudioSessionProperty_AudioRouteDescription, &routeSize);
    CFDictionaryRef desc; // this is the dictionary to contain descriptions

    // make the call to get the audio description and populate the desc dictionary
    AudioSessionGetProperty (kAudioSessionProperty_AudioRouteDescription, &routeSize, &desc);

    // the dictionary contains 2 keys, for input and output. Get output array
    CFArrayRef outputs = CFDictionaryGetValue(desc, kAudioSession_AudioRouteKey_Outputs);

    // the output array contains 1 element - a dictionary
    CFDictionaryRef diction = CFArrayGetValueAtIndex(outputs, 0);

    // get the output description from the dictionary
    CFStringRef output = CFDictionaryGetValue(diction, kAudioSession_AudioRouteKey_Type);
    return [NSString stringWithFormat:@"%@", output];
}

+ (NSString*) getAudioSessionRoute {
    /*
     returns the current session route:
     * ReceiverAndMicrophone
     * HeadsetInOut
     * Headset
     * HeadphonesAndMicrophone
     * Headphone
     * SpeakerAndMicrophone
     * Speaker
     * HeadsetBT
     * LineInOut
     * Lineout
     * Default
    */

    UInt32 rSize = sizeof (CFStringRef);
    CFStringRef route;
    AudioSessionGetProperty (kAudioSessionProperty_AudioRoute, &rSize, &route);

    if (route == NULL) {
        NSLog(@"Silent switch is currently on");
        return @"None";
    }
    return [NSString stringWithFormat:@"%@", route];
}

@end