我有一个AudioInputIOProc，我从AudioBufferList获得了AudioBufferList。我需要将此CMSampleBufferRef转换为- (void)handleAudioSamples:(const AudioBufferList*)samples numSamples:(UInt32)numSamples hostTime:(UInt64)hostTime {
// Create a CMSampleBufferRef from the list of samples, which we'll own
AudioStreamBasicDescription monoStreamFormat;
memset(&monoStreamFormat, 0, sizeof(monoStreamFormat));
monoStreamFormat.mSampleRate = 44100;
monoStreamFormat.mFormatID = kAudioFormatMPEG4AAC;
monoStreamFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked | kAudioFormatFlagIsNonInterleaved;
monoStreamFormat.mBytesPerPacket = 4;
monoStreamFormat.mFramesPerPacket = 1;
monoStreamFormat.mBytesPerFrame = 4;
monoStreamFormat.mChannelsPerFrame = 2;
monoStreamFormat.mBitsPerChannel = 16;
CMFormatDescriptionRef format = NULL;
OSStatus status = CMAudioFormatDescriptionCreate(kCFAllocatorDefault, &monoStreamFormat, 0, NULL, 0, NULL, NULL, &format);
if (status != noErr) {
// really shouldn't happen
return;
}
mach_timebase_info_data_t tinfo;
mach_timebase_info(&tinfo);
UInt64 _hostTimeToNSFactor = (double)tinfo.numer / tinfo.denom;
uint64_t timeNS = (uint64_t)(hostTime * _hostTimeToNSFactor);
CMTime presentationTime = CMTimeMake(timeNS, 1000000000);
CMSampleTimingInfo timing = { CMTimeMake(1, 44100), kCMTimeZero, kCMTimeInvalid };
CMSampleBufferRef sampleBuffer = NULL;
status = CMSampleBufferCreate(kCFAllocatorDefault, NULL, false, NULL, NULL, format, numSamples, 1, &timing, 0, NULL, &sampleBuffer);
if (status != noErr) {
// couldn't create the sample buffer
NSLog(@"Failed to create sample buffer");
CFRelease(format);
return;
}
// add the samples to the buffer
status = CMSampleBufferSetDataBufferFromAudioBufferList(sampleBuffer,
kCFAllocatorDefault,
kCFAllocatorDefault,
0,
samples);
if (status != noErr) {
NSLog(@"Failed to add samples to sample buffer");
CFRelease(sampleBuffer);
CFRelease(format);
NSLog(@"Error status code: %d", status);
return;
}
[self addAudioFrame:sampleBuffer];
NSLog(@"Original sample buf size: %ld for %d samples from %d buffers, first buffer has size %d", CMSampleBufferGetTotalSampleSize(sampleBuffer), numSamples, samples->mNumberBuffers, samples->mBuffers[0].mDataByteSize);
NSLog(@"Original sample buf has %ld samples", CMSampleBufferGetNumSamples(sampleBuffer));
}
。
这是我到目前为止编写的代码：
OSStatus AudioTee::InputIOProc(AudioDeviceID inDevice, const AudioTimeStamp *inNow, const AudioBufferList *inInputData, const AudioTimeStamp *inInputTime, AudioBufferList *outOutputData, const AudioTimeStamp *inOutputTime, void *inClientData)
现在，我不确定如何根据AudioInputIOProc的此函数定义计算numSamples：
CMSampleBufferError_RequiredParameterMissing此定义存在于WavTap的AudioTee.cpp文件中。
当我尝试拨打-12731时，我收到的错误是CMSampleBufferSetDataBufferFromAudioBufferList错误，错误代码为Channels: 2, Sample Rate: 44100, Precision: 32-bit, Sample Encoding: 32-bit Signed Integer PCM, Endian Type: little, Reverse Nibbles: no, Reverse Bits: no。
更新
为了澄清这个问题，以下是我从AudioDeviceIOProc获得的音频数据的格式：
AudioBufferList
我得到的CMSampleBufferRef *包含我需要转换为AVAssetWriterInput *的所有音频数据（30秒的视频），并将这些样本缓冲区添加到视频中（这是30秒长）通过> hlthgrpq1 <- brfss2013 %>% select(genhlth, X_ageg5yr)
写入磁盘。
答案 0 :(得分：3)
有三件事情看错：
您声明格式ID为kAudioFormatMPEG4AAC，但将其配置为LPCM。所以试试
monoStreamFormat.mFormatID = kAudioFormatLinearPCM;
当配置为立体声时，您也可以将格式称为“mono”。
为什么使用可能会在音频演示时间戳中留下空白的mach_timebase_info？请改用样本计数：
CMTime presentationTime = CMTimeMake(numSamplesProcessed, 44100);
您的CMSampleTimingInfo看起来不对，而且您没有使用presentationTime。您可以将缓冲区的持续时间设置为1个样本长，当它可以是numSamples时，将其显示时间设置为零，这可能是不正确的。这样的事情会更有意义：
CMSampleTimingInfo timing = { CMTimeMake(numSamples, 44100), presentationTime, kCMTimeInvalid };
还有一些问题：
您的AudioBufferList是否有预期的2 AudioBuffers？
你有这个可运行的版本吗？
P.S。我自己也对此感到内疚，但在音频开发中分配内存是considered harmful。