好的，所以我使用核心音频从 10 个不同的样本源中提取音频，然后在我的回调函数中将它们混合在一起。
它在模拟器中完美运行，一切都很好。但是，当我尝试在 4.2 iphone 设备上运行它时遇到了麻烦。
如果我在回调中混合 2 个音频文件，一切正常。如果我混合 5 或 6 个音频文件，音频会播放，但一段时间后音频会降级，最终不会有音频进入扬声器。（回调不会停止）。
如果我尝试混合 10 个音频文件，回调会运行，但根本没有音频出来。
几乎就像回调没有时间了，这可以解释我混合 5 或 6 个的情况，但不能解释最后一种情况，混合 10 个音频源而根本没有播放音频。
我不确定以下是否有任何影响，但是当我调试时，此消息总是打印到控制台。这是否可以说明问题所在？
mem 0x1000 0x3fffffff cache
mem 0x40000000 0xffffffff none
mem 0x00000000 0x0fff none
run
Running…
[Switching to thread 11523]
[Switching to thread 11523]
Re-enabling shared library breakpoint 1
continue
warning: Unable to read symbols for /Developer/Platforms/iPhoneOS.platform/DeviceSupport/4.2.1 (8C148)/Symbols/usr/lib/info/dns.so (file not found).
**设置我的回调**
#pragma mark -
#pragma mark Callback setup & control
- (void) setupCallback
{
OSStatus status;
// Describe audio component
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
// Get component
AudioComponent inputComponent = AudioComponentFindNext(NULL, &desc);
// Get audio units
status = AudioComponentInstanceNew(inputComponent, &audioUnit);
UInt32 flag = 1;
// Enable IO for playback
status = AudioUnitSetProperty(audioUnit,
kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Output,
kOutputBus,
&flag,
sizeof(flag));
//Apply format
status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Input,
kOutputBus,
&stereoStreamFormat,
sizeof(stereoStreamFormat));
// Set up the playback callback
AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = playbackCallback; //!!****assignment from incompatible pointer warning here *****!!!!!!
//set the reference to "self" this becomes *inRefCon in the playback callback
callbackStruct.inputProcRefCon = self;
status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_SetRenderCallback,
kAudioUnitScope_Global,
kOutputBus,
&callbackStruct,
sizeof(callbackStruct));
// Initialise
status = AudioUnitInitialize(audioUnit); // error check this status
}
回调
static OSStatus playbackCallback (
void *inRefCon, // A pointer to a struct containing the complete audio data
// to play, as well as state information such as the
// first sample to play on this invocation of the callback.
AudioUnitRenderActionFlags *ioActionFlags, // Unused here. When generating audio, use ioActionFlags to indicate silence
// between sounds; for silence, also memset the ioData buffers to 0.
AudioTimeStamp *inTimeStamp, // Unused here.
UInt32 inBusNumber, // The mixer unit input bus that is requesting some new
// frames of audio data to play.
UInt32 inNumberFrames, // The number of frames of audio to provide to the buffer(s)
// pointed to by the ioData parameter.
AudioBufferList *ioData // On output, the audio data to play. The callback's primary
// responsibility is to fill the buffer(s) in the
// AudioBufferList.
) {
Engine *remoteIOplayer = (Engine *)inRefCon;
AudioUnitSampleType *outSamplesChannelLeft;
AudioUnitSampleType *outSamplesChannelRight;
outSamplesChannelLeft = (AudioUnitSampleType *) ioData->mBuffers[0].mData;
outSamplesChannelRight = (AudioUnitSampleType *) ioData->mBuffers[1].mData;
int thetime =0;
thetime=remoteIOplayer.sampletime;
for (int frameNumber = 0; frameNumber < inNumberFrames; ++frameNumber)
{
// get NextPacket returns a 32 bit value, one frame.
AudioUnitSampleType *suml=0;
AudioUnitSampleType *sumr=0;
//NSLog (@"frame number - %i", frameNumber);
for(int j=0;j<10;j++)
{
AudioUnitSampleType valuetoaddl=0;
AudioUnitSampleType valuetoaddr=0;
//valuetoadd = [remoteIOplayer getSample:j ];
valuetoaddl = [remoteIOplayer getNonInterleavedSample:j currenttime:thetime channel:0 ];
//valuetoaddl = [remoteIOplayer getSample:j];
valuetoaddr = [remoteIOplayer getNonInterleavedSample:j currenttime:thetime channel:1 ];
suml = suml+(valuetoaddl/10);
sumr = sumr+(valuetoaddr/10);
}
outSamplesChannelLeft[frameNumber]=(AudioUnitSampleType) suml;
outSamplesChannelRight[frameNumber]=(AudioUnitSampleType) sumr;
remoteIOplayer.sampletime +=1;
}
return noErr;
}
我的音频提取功能
-(AudioUnitSampleType) getNonInterleavedSample:(int) index currenttime:(int)time channel:(int)ch;
{
AudioUnitSampleType returnvalue= 0;
soundStruct snd=soundStructArray[index];
UInt64 sn= snd.frameCount;
UInt64 st=sampletime;
UInt64 read= (UInt64)(st%sn);
if(ch==0)
{
if (snd.sendvalue==1) {
returnvalue = snd.audioDataLeft[read];
}else {
returnvalue=0;
}
}else if(ch==1)
{
if (snd.sendvalue==1) {
returnvalue = snd.audioDataRight[read];
}else {
returnvalue=0;
}
soundStructArray[index].sampleNumber=read;
}
if(soundStructArray[index].sampleNumber >soundStructArray[index].frameCount)
{
soundStructArray[index].sampleNumber=0;
}
return returnvalue;
}
编辑 1
作为对@andre 的回应，我将回调更改为以下内容，但它仍然没有帮助。
static OSStatus playbackCallback (
void *inRefCon, // A pointer to a struct containing the complete audio data
// to play, as well as state information such as the
// first sample to play on this invocation of the callback.
AudioUnitRenderActionFlags *ioActionFlags, // Unused here. When generating audio, use ioActionFlags to indicate silence
// between sounds; for silence, also memset the ioData buffers to 0.
AudioTimeStamp *inTimeStamp, // Unused here.
UInt32 inBusNumber, // The mixer unit input bus that is requesting some new
// frames of audio data to play.
UInt32 inNumberFrames, // The number of frames of audio to provide to the buffer(s)
// pointed to by the ioData parameter.
AudioBufferList *ioData // On output, the audio data to play. The callback's primary
// responsibility is to fill the buffer(s) in the
// AudioBufferList.
) {
Engine *remoteIOplayer = (Engine *)inRefCon;
AudioUnitSampleType *outSamplesChannelLeft;
AudioUnitSampleType *outSamplesChannelRight;
outSamplesChannelLeft = (AudioUnitSampleType *) ioData->mBuffers[0].mData;
outSamplesChannelRight = (AudioUnitSampleType *) ioData->mBuffers[1].mData;
int thetime =0;
thetime=remoteIOplayer.sampletime;
for (int frameNumber = 0; frameNumber < inNumberFrames; ++frameNumber)
{
// get NextPacket returns a 32 bit value, one frame.
AudioUnitSampleType suml=0;
AudioUnitSampleType sumr=0;
//NSLog (@"frame number - %i", frameNumber);
for(int j=0;j<16;j++)
{
soundStruct snd=remoteIOplayer->soundStructArray[j];
UInt64 sn= snd.frameCount;
UInt64 st=remoteIOplayer.sampletime;
UInt64 read= (UInt64)(st%sn);
suml+= snd.audioDataLeft[read];
suml+= snd.audioDataRight[read];
}
outSamplesChannelLeft[frameNumber]=(AudioUnitSampleType) suml;
outSamplesChannelRight[frameNumber]=(AudioUnitSampleType) sumr;
remoteIOplayer.sampletime +=1;
}
return noErr;
}