【发布时间】：2012-12-01 21:52:11
【问题描述】：
我正在尝试编写一个 iOS 应用程序，它将从麦克风接收到的声音传递到扬声器而不做任何更改。我已经阅读了苹果文档和指南。我从这个guide 中选择了第一个模式。但什么也没发生——沉默。如您所见，我尝试使用 AUAudioGraph（已评论）- 结果相同（在这个简单的示例中我是否需要它？）。
我在互联网上看到几个使用回调的例子，但我不想使用任何回调。有可能吗？
有什么建议吗？ 感谢关注。
实际代码
#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,
kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Output,
kOutputBus,
&flag,
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,
kAudioUnitScope_Output,
kInputBus,
&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
【问题讨论】：
-
看起来你做的一切都非常正确。但是，我看不到您实际将输入范围的输出元素连接到输出范围的输入元素的位置。 RemoteIO 单元的特殊之处在于它同时处理硬件输入和输出，但在实例化该单元时它们并没有隐式连接。
-
hmmm，您能否给我一个提示，我该如何实现它？你说的是AUAudioGraph吗？还是有其他方法可以在元素之间创建连接？谢谢。
-
谢谢，使用 AudioUnitConnection conn 完成； conn.destInputNumber = 0; conn.sourceAudioUnit = 单位； conn.sourceOutputNumber = 1; err = AudioUnitSetProperty(unit, kAudioUnitProperty_MakeConnection, kAudioUnitScope_Input, 0, &conn, sizeof(conn)); if (noErr != err) { [self showStatus:err]; }
标签： ios core-audio audiounit avaudiosession