AudioQueue volume too low

问题

I am having a problem when using AudioQueue to play PCM data. The volume is low when using the iPhone's speaker; I have even turned the system volume up to maximum. However, the volume is fine when I am using the earphones.

I inserted the data into the queue like this:

    memcpy(mBuffers[mIndex]->mAudioData, pcmData, mBufferByteSize);
    mBuffers[mIndex]->mAudioDataByteSize = mBufferByteSize;
    mBuffers[mIndex]->mPacketDescriptionCount = mBufferByteSize/2;
    OSStatus status = AudioQueueEnqueueBuffer(mQueue, mBuffers[mIndex], 0, NULL);
    NSLog(@"fill audio queue buffer[%d]",mIndex);
    if(mIndex == kNumberBuffers - 1) {
        isStartPlay = YES;
        mIndex = 0;
        AudioQueueSetParameter(mQueue, kAudioQueueParam_Volume, 1.0);
        status = AudioQueueStart(mQueue, NULL);
    }else {
        mIndex++;
    }

I have set the volume like this:

    AudioQueueSetParameter(mQueue, kAudioQueueParam_Volume, 1.0);

回答1:

For those still having this issue which is even on SpeakHere sample code. This solution worked well for me out of all the other ones :

//ViewController.m

#import "ViewController.h"


@interface ViewController ()
{ AVAudioSession *session; }

- (void)viewDidLoad {
    [super viewDidLoad];

    //This ensures it plays properly on speaker output
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord
                                     withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker
                                           error:nil];

}

来源：https://stackoverflow.com/questions/32599351/audioqueue-volume-too-low