/// <summary> /// Default constructor. /// </summary> /// <param name="outputDevice">Output device.</param> /// <param name="samplesPerSec">Sample rate, in samples per second (hertz). For PCM common values are /// 8.0 kHz, 11.025 kHz, 22.05 kHz, and 44.1 kHz.</param> /// <param name="bitsPerSample">Bits per sample. For PCM 8 or 16 are the only valid values.</param> /// <param name="channels">Number of channels.</param> /// <exception cref="ArgumentNullException">Is raised when <b>outputDevice</b> is null.</exception> /// <exception cref="ArgumentException">Is raised when any of the aruments has invalid value.</exception> public WaveOut(WavOutDevice outputDevice, int samplesPerSec, int bitsPerSample, int channels) { if (outputDevice == null) { throw new ArgumentNullException("outputDevice"); } if (samplesPerSec < 8000) { throw new ArgumentException("Argument 'samplesPerSec' value must be >= 8000."); } if (bitsPerSample < 8) { throw new ArgumentException("Argument 'bitsPerSample' value must be >= 8."); } if (channels < 1) { throw new ArgumentException("Argument 'channels' value must be >= 1."); } m_pOutDevice = outputDevice; m_SamplesPerSec = samplesPerSec; m_BitsPerSample = bitsPerSample; m_Channels = channels; m_BlockSize = m_Channels * (m_BitsPerSample / 8); m_pPlayItems = new List <PlayItem>(); // Try to open wav device. WAVEFORMATEX format = new WAVEFORMATEX(); format.wFormatTag = WavFormat.PCM; format.nChannels = (ushort)m_Channels; format.nSamplesPerSec = (uint)samplesPerSec; //1秒钟数据量(字节/秒)= (采样频率(Hz)*采样位数(bit)*声道数)/ 8 //换算成20ms的数据量则再除50 format.nAvgBytesPerSec = (uint)((m_SamplesPerSec * m_Channels * (m_BitsPerSample / 8))) / 50; format.nBlockAlign = (ushort)m_BlockSize; format.wBitsPerSample = (ushort)m_BitsPerSample; format.cbSize = 0; m_MinBuffer = (int)format.nAvgBytesPerSec * 10; // We must delegate reference, otherwise GC will collect it. m_pWaveOutProc = new waveOutProc(this.OnWaveOutProc); int result = WavMethods.waveOutOpen(out m_pWavDevHandle, m_pOutDevice.Index, format, m_pWaveOutProc, 0, WavConstants.CALLBACK_FUNCTION); if (result != MMSYSERR.NOERROR) { throw new Exception("Failed to open wav device, error: " + result.ToString() + "."); } }