提供一点上下文。我正尝试从c#应用程序中的相机输出实时音频。做了一些研究后,在C++托管的dll中执行它似乎很明显。我选择了XAudio2 API,因为它应该很容易实现和使用动态音频内容。XAudio2 - 使用动态缓冲区时打开输出
所以这个想法是用C++创建一个空缓冲区的XAudio设备,并从C#代码端推入音频。音频块每隔50ms被推送一次,因为我希望尽可能缩短延迟。定时器运行它
// SampleRate = 44100; Channels = 2; BitPerSample = 16;
var blockAlign = (Channels * BitsPerSample)/8;
var avgBytesPerSecond = SampleRate * blockAlign;
var avgBytesPerMillisecond = avgBytesPerSecond/1000;
var bufferSize = avgBytesPerMillisecond * Time;
_sampleBuffer = new byte[bufferSize];
每次获取音频缓冲器的指针,从音频读取数据,将数据复制到指针并调用PushAudio方法。 我也使用秒表来检查处理过程花了多长时间,并再次计算定时器的时间间隔以包含处理时间。
private void PushAudioChunk(object sender, ElapsedEventArgs e)
{
unsafe
{
_pushAudioStopWatch.Reset();
_pushAudioStopWatch.Start();
var audioBufferPtr = Output.AudioCapturerBuffer();
FillBuffer(_sampleBuffer);
Marshal.Copy(_sampleBuffer, 0, (IntPtr)audioBufferPtr, _sampleBuffer.Length);
Output.PushAudio();
_pushTimer.Interval = Time - _pushAudioStopWatch.ElapsedMilliseconds;
_pushAudioStopWatch.Stop();
DIX.Log.WriteLine("Push audio took: {0}ms", _pushAudioStopWatch.ElapsedMilliseconds);
}
}
这是C++部分的实现。
关于msdn的文档,我创建了一个XAudio2设备并添加了MasterVoice和SourceVoice。起初缓冲区是空的,因为c#部分负责推入音频数据。
namespace Audio
{
using namespace System;
template <class T> void SafeRelease(T **ppT)
{
if (*ppT)
{
(*ppT)->Release();
*ppT = NULL;
}
}
WAVEFORMATEXTENSIBLE wFormat;
XAUDIO2_BUFFER buffer = { 0 };
IXAudio2* pXAudio2 = NULL;
IXAudio2MasteringVoice* pMasterVoice = NULL;
IXAudio2SourceVoice* pSourceVoice = NULL;
WaveOut::WaveOut(int bufferSize)
{
audioBuffer = new Byte[bufferSize];
wFormat.Format.wFormatTag = WAVE_FORMAT_PCM;
wFormat.Format.nChannels = 2;
wFormat.Format.nSamplesPerSec = 44100;
wFormat.Format.wBitsPerSample = 16;
wFormat.Format.nBlockAlign = (wFormat.Format.nChannels * wFormat.Format.wBitsPerSample)/8;
wFormat.Format.nAvgBytesPerSec = wFormat.Format.nSamplesPerSec * wFormat.Format.nBlockAlign;
wFormat.Format.cbSize = 0;
wFormat.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
HRESULT hr = XAudio2Create(&pXAudio2, 0, XAUDIO2_DEFAULT_PROCESSOR);
if (SUCCEEDED(hr))
{
hr = pXAudio2->CreateMasteringVoice(&pMasterVoice);
}
if (SUCCEEDED(hr))
{
hr = pXAudio2->CreateSourceVoice(&pSourceVoice, (WAVEFORMATEX*)&wFormat,
0, XAUDIO2_DEFAULT_FREQ_RATIO, NULL, NULL, NULL);
}
buffer.pAudioData = (BYTE*)audioBuffer;
buffer.AudioBytes = bufferSize;
buffer.Flags = 0;
if (SUCCEEDED(hr))
{
hr = pSourceVoice->Start(0);
}
}
WaveOut::~WaveOut()
{
}
WaveOut^ WaveOut::CreateWaveOut(int bufferSize)
{
return gcnew WaveOut(bufferSize);
}
uint8_t* WaveOut::AudioCapturerBuffer()
{
if (!audioBuffer)
{
throw gcnew Exception("Audio buffer is not initialized. Did you forget to set up the audio container?");
}
return (BYTE*)audioBuffer;
}
int WaveOut::PushAudio()
{
HRESULT hr = pSourceVoice->SubmitSourceBuffer(&buffer);
if (FAILED(hr))
{
return -1;
}
return 0;
}
}
我面临的问题是,我总是有一些输出开裂。我试图增加定时器的间隔或增加缓冲区大小。每次都有相同的结果。
我在做什么错?
更新:
我在3个缓冲区XAudio引擎可以顺利通过。裂开了。现在缺少的部分是在c#部分的正确时间填充缓冲区,以避免使用相同数据的缓冲区。
void Render(void* param)
{
std::vector<byte> audioBuffers[BUFFER_COUNT];
size_t currentBuffer = 0;
// Get the current state of the source voice
while (BackgroundThreadRunning && pSourceVoice)
{
if (pSourceVoice)
{
pSourceVoice->GetState(&state);
}
while (state.BuffersQueued < BUFFER_COUNT)
{
std::vector<byte> resultData;
resultData.resize(DATA_SIZE);
CopyMemory(&resultData[0], pAudioBuffer, DATA_SIZE);
// Retreive the next buffer to stream from MF Music Streamer
audioBuffers[currentBuffer] = resultData;
// Submit the new buffer
XAUDIO2_BUFFER buf = { 0 };
buf.AudioBytes = static_cast<UINT32>(audioBuffers[currentBuffer].size());
buf.pAudioData = &audioBuffers[currentBuffer][0];
pSourceVoice->SubmitSourceBuffer(&buf);
// Advance the buffer index
currentBuffer = ++currentBuffer % BUFFER_COUNT;
// Get the updated state
pSourceVoice->GetState(&state);
}
Sleep(30);
}
}
在黑暗中野生刺伤 - 你有没有尝试清空缓冲区? – BugFinder
你好。不,我没有。我应该怎么做?在推新音频块之前? – datoml
定义它之后,只需将每个字节设置为0 – BugFinder