private void btnOpenSound_Click(object sender, EventArgs e) { // private Int32 m_iPreviewType = 0; if (m_lRealHandle < 0) { MessageBox.Show("Please preview first"); } else { if (m_iPreviewType == 0) // callback { if (!m_bOpenSound) { if (PlayCtrl.PlayM4_PlaySound(m_lPort)) { m_bOpenSound = true; btnOpenSound.Text = "Stop sound"; } else { Debug.Print("Fail to open sound"); } } else { if (PlayCtrl.PlayM4_StopSound()) { m_bOpenSound = false; btnOpenSound.Text = "Open sound"; } } } else // Sdk decode { if (!m_bOpenSound) { if (CHCNetSDK.NET_DVR_OpenSound(m_lRealHandle)) { m_bOpenSound = true; btnOpenSound.Text = "Stop sound"; } else { Debug.Print("Fail to open sound"); } } else { if (CHCNetSDK.NET_DVR_CloseSound()) { m_bOpenSound = false; btnOpenSound.Text = "Open sound"; } } } } }