iOS AudioUnits通过

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前端之家收集整理的这篇文章主要介绍了iOS AudioUnits通过，前端之家小编觉得挺不错的，现在分享给大家，也给大家做个参考。
我正在尝试编写一个iOS应用程序,它将从麦克风接收的声音传递给扬声器而不做任何更改.我读过苹果文档和指南.我从这个 guide中选择了第一个模式.但是什么也没发生 – 沉默.正如你所看到的,我已经尝试使用AUAudioGraph(注释) – 结果相同(我在这个简单的例子中是否需要它？).

我在互联网上看到了几个使用回调的例子,但我不想使用任何回调.可能吗？

有什么建议？
谢谢你的关注.

实际的代码

#import "AudioController.h"
#import <AudioToolBox/AudioToolBox.h>
#import <AVFoundation/AVFoundation.h>
#import <AudioToolBox/AudioServices.h>
#define kInputBus 1
#define kOutputBus 0

@interface AudioController ()
{
    AudioComponentDescription desc;
    AudioComponent component;
    AudioUnit unit;
    AudioStreamBasicDescription audioFormat;
    double rate;
    //AUGraph graph;
}


@end

@implementation AudioController

- (void) setUp {
    AVAudioSession *sess = [AVAudioSession sharedInstance];
    NSError *error = nil;
    rate = 44100.0;
    [sess setPreferredSampleRate:rate error:&error];
    [sess setCategory:AVAudioSessionCategoryPlayAndRecord error:&error];
    [sess setActive:YES error:&error];
    rate = [sess sampleRate];
    if (error) {
        NSLog(@"%@",error);
    }

    NSLog(@"Init...");
    [self createUnitDesc];
    [self getComponent];
    [self getAudioUnit];
    [self enableIORec];
    [self enableIOPb];
    [self createFormat];
    [self applyFormat];
    OSStatus err = AudioUnitInitialize(unit);
    if (noErr != err) {
        [self showStatus:err];
    }
    /*NewAUGraph(&graph);
    AUNode node;
    AUGraphAddNode(graph,&desc,&node);
AUGraphInitialize(graph);
AUGraphOpen(graph);*/
}

- (void) createUnitDesc {
    desc.componentType = kAudioUnitType_Output;
    desc.componentSubType = kAudioUnitSubType_RemoteIO;
    desc.componentFlags = 0;
    desc.componentFlagsMask = 0;
    desc.componentManufacturer = kAudioUnitManufacturer_Apple;

}

- (void) getComponent {
    component = AudioComponentFindNext(NULL,&desc);
}

- (void) getAudioUnit {
    OSStatus res = AudioComponentInstanceNew(component,&unit);
    if (noErr != res) {
        [self showStatus:res];
    }
}

- (void) enableIORec {
    UInt32 flag = 1;
    OSStatus err = AudioUnitSetProperty(unit,kAudioOutputUnitProperty_EnableIO,kAudioUnitScope_Input,kInputBus,&flag,sizeof(flag));
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void) enableIOPb {
    UInt32 flag = 1;
    OSStatus err = AudioUnitSetProperty(unit,kAudioUnitScope_Output,kOutputBus,sizeof(flag));
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void) createFormat {
    // Describe format
    audioFormat.mSampleRate         = rate;//44100.00;
    audioFormat.mFormatID           = kAudioFormatLinearPCM;
    audioFormat.mFormatFlags        = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
    audioFormat.mFramesPerPacket    = 1;
    audioFormat.mChannelsPerFrame   = 1;
    audioFormat.mBitsPerChannel     = 16;
    audioFormat.mBytesPerPacket     = 2;
    audioFormat.mBytesPerFrame      = 2;
}

- (void) applyFormat {
    OSStatus err = AudioUnitSetProperty(unit,kAudioUnitProperty_StreamFormat,&audioFormat,sizeof(audioFormat));
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void) start {
    NSLog(@"starting");
    OSStatus err = AudioOutputUnitStart(unit);
    //AUGraphStart(graph);
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void) end {
    NSLog(@"ending");
    OSStatus err = AudioOutputUnitStop(unit);
    //AUGraphStop(graph);
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void) showStatus:(OSStatus) st{
    NSString *text = nil;
    switch (st) {
        case kAudioUnitErr_CannotDoInCurrentContext: text = @"kAudioUnitErr_CannotDoInCurrentContext"; break;
        case kAudioUnitErr_FailedInitialization: text = @"kAudioUnitErr_FailedInitialization"; break;
        case kAudioUnitErr_FileNotSpecified: text = @"kAudioUnitErr_FileNotSpecified"; break;
        case kAudioUnitErr_FormatNotSupported: text = @"kAudioUnitErr_FormatNotSupported"; break;
        case kAudioUnitErr_IllegalInstrument: text = @"kAudioUnitErr_IllegalInstrument"; break;
        case kAudioUnitErr_Initialized: text = @"kAudioUnitErr_Initialized"; break;
        case kAudioUnitErr_InstrumentTypeNotFound: text = @"kAudioUnitErr_InstrumentTypeNotFound"; break;
        case kAudioUnitErr_InvalidElement: text = @"kAudioUnitErr_InvalidElement"; break;
        case kAudioUnitErr_InvalidFile: text = @"kAudioUnitErr_InvalidFile"; break;
        case kAudioUnitErr_InvalidOfflineRender: text = @"kAudioUnitErr_InvalidOfflineRender"; break;
        case kAudioUnitErr_InvalidParameter: text = @"kAudioUnitErr_InvalidParameter"; break;
        case kAudioUnitErr_InvalidProperty: text = @"kAudioUnitErr_InvalidProperty"; break;
        case kAudioUnitErr_InvalidPropertyValue: text = @"kAudioUnitErr_InvalidPropertyValue"; break;
        case kAudioUnitErr_InvalidScope: text = @"kAudioUnitErr_InvalidScope"; break;
        case kAudioUnitErr_NoConnection: text = @"kAudioUnitErr_NoConnection"; break;
        case kAudioUnitErr_PropertyNotInUse: text = @"kAudioUnitErr_PropertyNotInUse"; break;
        case kAudioUnitErr_PropertyNotWritable: text = @"kAudioUnitErr_PropertyNotWritable"; break;
        case kAudioUnitErr_TooManyFramesToProcess: text = @"kAudioUnitErr_TooManyFramesToProcess"; break;
        case kAudioUnitErr_Unauthorized: text = @"kAudioUnitErr_Unauthorized"; break;
        case kAudioUnitErr_Uninitialized: text = @"kAudioUnitErr_Uninitialized"; break;
        case kAudioUnitErr_UnknownFileType: text = @"kAudioUnitErr_UnknownFileType"; break;
        default: text = @"unknown error";
    }
    NSLog(@"TRANSLATED_ERROR = %li = %@",st,text);
}

- (void) dealloc {
    AudioUnitUninitialize(unit);

    [super dealloc];
}

@end

解决方法

正如warrenm所说,在Remote IO元素之间建立连接有所帮助.
所以在完成所有初始化后放置的代码： 
AudioUnitConnection conn;
conn.destInputNumber = kOutputBus;
conn.sourceAudioUnit = unit;
conn.sourceOutputNumber = kInputBus;
err = AudioUnitSetProperty(unit,kAudioUnitProperty_MakeConnection,&conn,sizeof(conn));
if (noErr != err) { [self showStatus:err]; }

UPDATE
为了方便其他人使用该解决方案,我将在此处发布完整代码：

.h文件

#import <Foundation/Foundation.h>

@interface AudioController : NSObject

- (void)setUp;
- (void)start;
- (void)end;
@end

.m文件

#import "AudioController.h"
#import <AudioToolBox/AudioToolBox.h>
#import <AVFoundation/AVFoundation.h>
#import <AudioToolBox/AudioServices.h>
#define kInputBus 1
#define kOutputBus 0

@interface AudioController ()
{
    AudioComponentDescription desc;
    AudioComponent component;
    AudioUnit unit;
    AudioStreamBasicDescription audioFormat;
    double rate;
}
@end

@implementation AudioController

- (void)setUp
{
    AVAudioSession *sess = [AVAudioSession sharedInstance];
    NSError *error = nil;
    rate = 44100.0;
    [sess setPreferredSampleRate:rate error:&error];
    [sess setCategory:AVAudioSessionCategoryPlayAndRecord error:&error];
    [sess setActive:YES error:&error];
    rate = [sess sampleRate];
    if (error) {
        NSLog(@"%@",error);
    }

    NSLog(@"Initing");
    [self createUnitDesc];
    [self getComponent];
    [self getAudioUnit];
    [self enableIORec];
    [self enableIOPb];
    [self createFormat];
    [self applyFormat];
    OSStatus err = AudioUnitInitialize(unit);
    if (noErr != err) {
        [self showStatus:err];
    }

    AudioUnitConnection conn;
    conn.destInputNumber = 0;
    conn.sourceAudioUnit = unit;
    conn.sourceOutputNumber = 1;
    err = AudioUnitSetProperty(unit,sizeof(conn));
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void)createUnitDesc
{
    desc.componentType = kAudioUnitType_Output;
    desc.componentSubType = kAudioUnitSubType_RemoteIO;
    desc.componentFlags = 0;
    desc.componentFlagsMask = 0;
    desc.componentManufacturer = kAudioUnitManufacturer_Apple;

}

- (void)getComponent
{
    component = AudioComponentFindNext(NULL,&desc);
}

- (void)getAudioUnit
{
    OSStatus res = AudioComponentInstanceNew(component,&unit);
    if (noErr != res) {
        [self showStatus:res];
    }
}

- (void)enableIORec
{
    UInt32 flag = 1;
    OSStatus err = AudioUnitSetProperty(unit,sizeof(flag));
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void)enableIOPb
{
    UInt32 flag = 1;
    OSStatus err = AudioUnitSetProperty(unit,sizeof(flag));
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void)createFormat
{
    // Describe format
    audioFormat.mSampleRate         = rate;
    audioFormat.mFormatID           = kAudioFormatLinearPCM;
    audioFormat.mFormatFlags        = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
    audioFormat.mFramesPerPacket    = 1;
    audioFormat.mChannelsPerFrame   = 1;
    audioFormat.mBitsPerChannel     = 16;
    audioFormat.mBytesPerPacket     = 2;
    audioFormat.mBytesPerFrame      = 2;
}

- (void)applyFormat
{
    OSStatus err = AudioUnitSetProperty(unit,sizeof(audioFormat));
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void)start
{
    NSLog(@"starting");
    OSStatus err = AudioOutputUnitStart(unit);
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void)end
{
    NSLog(@"ending");
    OSStatus err = AudioOutputUnitStop(unit);
    if (noErr != err) {
        [self showStatus:err];
    }
}

- (void)showStatus:(OSStatus)st
{
    NSString *text = nil;
    switch (st) {
        case kAudioUnitErr_CannotDoInCurrentContext: text = @"kAudioUnitErr_CannotDoInCurrentContext"; break;
        case kAudioUnitErr_FailedInitialization: text = @"kAudioUnitErr_FailedInitialization"; break;
        case kAudioUnitErr_FileNotSpecified: text = @"kAudioUnitErr_FileNotSpecified"; break;
        case kAudioUnitErr_FormatNotSupported: text = @"kAudioUnitErr_FormatNotSupported"; break;
        case kAudioUnitErr_IllegalInstrument: text = @"kAudioUnitErr_IllegalInstrument"; break;
        case kAudioUnitErr_Initialized: text = @"kAudioUnitErr_Initialized"; break;
        case kAudioUnitErr_InstrumentTypeNotFound: text = @"kAudioUnitErr_InstrumentTypeNotFound"; break;
        case kAudioUnitErr_InvalidElement: text = @"kAudioUnitErr_InvalidElement"; break;
        case kAudioUnitErr_InvalidFile: text = @"kAudioUnitErr_InvalidFile"; break;
        case kAudioUnitErr_InvalidOfflineRender: text = @"kAudioUnitErr_InvalidOfflineRender"; break;
        case kAudioUnitErr_InvalidParameter: text = @"kAudioUnitErr_InvalidParameter"; break;
        case kAudioUnitErr_InvalidProperty: text = @"kAudioUnitErr_InvalidProperty"; break;
        case kAudioUnitErr_InvalidPropertyValue: text = @"kAudioUnitErr_InvalidPropertyValue"; break;
        case kAudioUnitErr_InvalidScope: text = @"kAudioUnitErr_InvalidScope"; break;
        case kAudioUnitErr_NoConnection: text = @"kAudioUnitErr_NoConnection"; break;
        case kAudioUnitErr_PropertyNotInUse: text = @"kAudioUnitErr_PropertyNotInUse"; break;
        case kAudioUnitErr_PropertyNotWritable: text = @"kAudioUnitErr_PropertyNotWritable"; break;
        case kAudioUnitErr_TooManyFramesToProcess: text = @"kAudioUnitErr_TooManyFramesToProcess"; break;
        case kAudioUnitErr_Unauthorized: text = @"kAudioUnitErr_Unauthorized"; break;
        case kAudioUnitErr_Uninitialized: text = @"kAudioUnitErr_Uninitialized"; break;
        case kAudioUnitErr_UnknownFileType: text = @"kAudioUnitErr_UnknownFileType"; break;
        default: text = @"unknown error";
    }
    NSLog(@"TRANSLATED_ERROR = %li = %@",text);
}

- (void)dealloc
{
    AudioUnitUninitialize(unit);

    [super dealloc];
}

@end
原文链接：https://www.f2er.com/iOS/328076.html

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