现场AAC编码音频单元 [英] live AAC encoding with audio units
本文介绍了现场AAC编码音频单元的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我试图做一些与流媒体音频单元服务和音频转换器服务，但我有点卡住了。我的目标是夺取麦克风输入（PCM），将其转换就飞到AAC，并通过网络发送数据包。这似乎工作，但音频是可怕的，4S后，应用程序崩溃
I'm trying to do some streaming with Audio Unit Services and Audio Converter Service but I'm a bit stuck. My goal is to capture microphone input (PCM), convert it on the fly to AAC and send the packet over the network. It seems to works but the audio is terrible and the app crash after 4s
//初始化音频单元
OSStatus status;
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
AudioComponent component = AudioComponentFindNext(NULL, &desc);
status = AudioComponentInstanceNew(component, &_audioUnit);
NSLog(@"status instance new: %lu",status);
UInt32 flag = 1;
status = AudioUnitSetProperty(_audioUnit,
kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Input,
1,
&flag,
sizeof(flag));
NSLog(@"status AudioUnitSetProperty input: %lu",status);
AudioStreamBasicDescription audioFormat;
memset(&audioFormat, 0, sizeof(AudioStreamBasicDescription));
audioFormat.mSampleRate = 44100;
audioFormat.mFormatID = kAudioFormatLinearPCM;
audioFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
audioFormat.mFramesPerPacket = 1;
audioFormat.mChannelsPerFrame = 1;
audioFormat.mBitsPerChannel = 16;
audioFormat.mBytesPerPacket =
audioFormat.mBytesPerFrame = audioFormat.mChannelsPerFrame * sizeof(SInt16);
status = AudioUnitSetProperty(_audioUnit,
kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Input,
0,
&audioFormat,
sizeof(audioFormat));
NSLog(@"status AudioUnitSetProperty audioFormat: %lu",status);
AURenderCallbackStruct renderCallbackInfo;
renderCallbackInfo.inputProc = recordingCallback;
renderCallbackInfo.inputProcRefCon = NULL;
AudioUnitSetProperty(_audioUnit,
kAudioOutputUnitProperty_SetInputCallback,
kAudioUnitScope_Global,
1,
&renderCallbackInfo,
sizeof(renderCallbackInfo));
float aBufferLength = 0.005; // In seconds
AudioSessionSetProperty(kAudioSessionProperty_PreferredHardwareIOBufferDuration,
sizeof(aBufferLength), &aBufferLength);
_converter = [[Converter alloc] initWithFormat];
status = AudioUnitInitialize(_audioUnit);
NSLog(@"status AudioUnit initialize: %lu",status);
//记录回调：
//recording callback :
static OSStatus recordingCallback(void *inRefCon,
AudioUnitRenderActionFlags *ioActionFlags,
const AudioTimeStamp *inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList *ioData) {
AudioBufferList bufferList;
bufferList.mNumberBuffers = 1;
bufferList.mBuffers[0].mNumberChannels = 1;
bufferList.mBuffers[0].mData = NULL;
bufferList.mBuffers[0].mDataByteSize = inNumberFrames * sizeof(SInt16);
OSStatus status = AudioUnitRender(_audioUnit, ioActionFlags, inTimeStamp,1, inNumberFrames, &bufferList);
AudioBuffer aac;
pcm.mData = malloc(inNumberFrames * sizeof(SInt16));
unsigned char * p = malloc(inNumberFrames * sizeof(SInt16));
memcpy(p, bufferList.mBuffers[0].mData, inNumberFrames * sizeof(SInt16));
memcpy(pcm.mData,p,bufferList.mBuffers[0].mDataByteSize); // dunno why i can't memcpy bufferlist data directly to pcm struct
pcm.mDataByteSize = inNumberFrames * sizeof(SInt16);
pcm.mNumberChannels = 1;
int osstatus = [_converter convertAudioBuffer:&pcm EncodedAudioBuffer:&aac];
// send to the network
NSData* data = [[NSData alloc]initWithBytes:aac.mData length:aac.mDataByteSize];
dispatch_async(myQueue, ^{_pts+=1024;[sender sendBuf2:data withTime:_pts];});
return noErr;
}
//转换器侧：
// converter side :
-(int) convertAudioBuffer:(AudioBuffer*)inSamples EncodedAudioBuffer:(AudioBuffer*) outData{
memset(_buffer, 0, _converterSettings.maxPacketSize);
_converterSettings.buffer = *inSamples;
//_converterSettings.bytesToEncode = inSamples->mDataByteSize;
UInt32 ioOutputDataPackets = 1;
AudioStreamPacketDescription outPacketDesc[1];
AudioBufferList convertedData;
convertedData.mNumberBuffers = 1;
convertedData.mBuffers[0].mNumberChannels = 1;
convertedData.mBuffers[0].mDataByteSize = _converterSettings.maxPacketSize;
convertedData.mBuffers[0].mData = _buffer;
OSStatus error = AudioConverterFillComplexBuffer(_audioConverter,
MyAudioConverterCallback,
&_converterSettings,
&ioOutputDataPackets,
&convertedData,
outPacketDesc);
if (error != noErr)
{
NSError *err = [NSError errorWithDomain:NSOSStatusErrorDomain code:error userInfo:nil];
NSLog(@"%ld",convertedData.mBuffers[0].mDataByteSize);
}
NSLog(@"%ld",convertedData.mBuffers[0].mDataByteSize);
/* Set the ouput data */
outData->mNumberChannels = convertedData.mBuffers[0].mNumberChannels;
outData->mDataByteSize = convertedData.mBuffers[0].mDataByteSize;
outData->mData = convertedData.mBuffers[0].mData;
return 0;
}
PROC回调：
proc callback :
OSStatus MyAudioConverterCallback(AudioConverterRef inAudioConverter,
UInt32 *ioDataPacketCount,
AudioBufferList *ioData,
AudioStreamPacketDescription **outDataPacketDescription,
void *inUserData)
{
if (outDataPacketDescription)
{
*outDataPacketDescription = NULL;
}
Settings *audioConverterSettings = (Settings *)inUserData;
ioData->mBuffers[0].mData = audioConverterSettings->buffer.mData;
ioData->mBuffers[0].mDataByteSize = audioConverterSettings->buffer.mDataByteSize;
ioData->mBuffers[0].mNumberChannels = audioConverterSettings->buffer.mNumberChannels;
return noErr;
}
和最后的输出：
2013-07-16 16:58:57.192 AudioUnitAAC[84656:c07] status instance new: 0
2013-07-16 16:58:57.195 AudioUnitAAC[84656:c07] status AudioUnitSetProperty input: 0
2013-07-16 16:58:57.197 AudioUnitAAC[84656:c07] status AudioUnitSetProperty audioFormat: 0
2013-07-16 16:58:57.235 AudioUnitAAC[84656:c07] status AudioUnit initialize: 0
2013-07-16 16:58:58.182 AudioUnitAAC[84656:c07] start : 0
2013-07-16 16:58:58.200 AudioUnitAAC[84656:6e07] 4 bytes encoded
2013-07-16 16:58:58.211 AudioUnitAAC[84656:6e07] 152 bytes encoded
2013-07-16 16:58:58.223 AudioUnitAAC[84656:6e07] 169 bytes encoded
2013-07-16 16:58:58.235 AudioUnitAAC[84656:6e07] 157 bytes encoded
2013-07-16 16:58:58.246 AudioUnitAAC[84656:6e07] 160 bytes encoded
2013-07-16 16:58:58.258 AudioUnitAAC[84656:6e07] 164 bytes encoded
....
直到crashs了一些随机的原因（AudioConverterFillComplexBuffer坏的访问，的NSLog（@％LD，convertedData.mBuffers [0] .mDataByteSize）坏指令...）
until it crashs for some random reason (AudioConverterFillComplexBuffer bad access, NSLog(@"%ld",convertedData.mBuffers[0].mDataByteSize) bad instruction...)
我是新苹果音频核心，任何帮助，将AP preciated :)
I'm new with apple audio core and any help would be appreciated :)
推荐答案
由于这个职位，我得到它的工作！我更改：
Thanks to this post I got it to work! I Changed:
pcm.mData = malloc(inNumberFrames * sizeof(SInt16));
unsigned char * p = malloc(inNumberFrames * sizeof(SInt16));
memcpy(p, bufferList.mBuffers[0].mData, inNumberFrames * sizeof(SInt16));
memcpy(pcm.mData,p,bufferList.mBuffers[0].mDataByteSize); // dunno why i can't memcpy bufferlist data directly to pcm struct
pcm.mDataByteSize = inNumberFrames * sizeof(SInt16);
pcm.mNumberChannels = 1;
到
memset(&audioBuffer, 0, sizeof(AudioBufferList));
memset(&audioBuffer.mBuffers[0], 0, sizeof(AudioBuffer));
audioBuffer.mNumberBuffers = 1;
audioBuffer.mBuffers[0].mNumberChannels = bufferList->mBuffers[0].mNumberChannels;
audioBuffer.mBuffers[0].mDataByteSize = bufferList->mBuffers[0].mDataByteSize;
audioBuffer.mBuffers[0].mData = bufferList->mBuffers[0].mData;
和回调我这样做：
ioData->mBuffers[0].mData = audioBuffer.mBuffers[0].mData;
ioData->mBuffers[0].mDataByteSize = audioBuffer.mBuffers[0].mDataByteSize;
ioData->mBuffers[0].mNumberChannels = audioBuffer.mBuffers[0].mNumberChannels;
这篇关于现场AAC编码音频单元的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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