/// <summary>Opens a MIDI file.</summary>
/// <remarks>Used interally only.</remarks>
/// <exceptions cref="MediaException">Thrown when there was an error opening the file.</exceptions>
/// <exceptions cref="FileNotFoundException">Thrown when the specified file could not be found.</exceptions>
protected void OpenFile()
{
if (!File.Exists(Filename))
{
throw new FileNotFoundException();
}
MCI_OPEN_PARMS mciOpenParms = new MCI_OPEN_PARMS();
mciOpenParms.lpstrDeviceType = "sequencer";
mciOpenParms.lpstrElementName = Filename;
if (mciSendCommandOpen(0, MCI_OPEN, MCI_OPEN_TYPE | MCI_OPEN_ELEMENT, ref mciOpenParms) != 0)
{
throw new MediaException("Failed to open the MIDI device.");
}
// The device opened successfully; get the device ID.
DeviceID = mciOpenParms.wDeviceID;
// Get the length of the MIDI file
MCI_STATUS_PARMS mciStatusParms = new MCI_STATUS_PARMS();
mciStatusParms.dwItem = MCI_STATUS_LENGTH;
if (mciSendCommandStatus(DeviceID, MCI_STATUS, MCI_WAIT | MCI_STATUS_ITEM, ref mciStatusParms) != 0)
{
throw new MediaException("Couldn't get the length of the specified MIDI file.");
}
m_Length = mciStatusParms.dwReturn;
}
/// <summary>
/// 获取音频文件的总时长
/// </summary>
/// <returns>返回音频文件的总时长</returns>
public TimeSpan GetLength()
{
// Get audio length in millisecs
if (m_DeviceID != 0)
{
MCI_STATUS_PARMS sp = new MCI_STATUS_PARMS();
sp.dwCallback = IntPtr.Zero;
sp.dwItem = MCI_Status.MCI_STATUS_LENGTH;
IntPtr spPointer = Marshal.AllocHGlobal(Marshal.SizeOf(sp));
try
{
Marshal.StructureToPtr(sp, spPointer, false);
UInt32 errorCode = mciSendCommand(m_DeviceID, (UInt32)MCI_Command.MCI_STATUS, (UInt32)(MCI_StatusFlags.MCI_WAIT | MCI_StatusFlags.MCI_STATUS_ITEM), spPointer);
CheckError(errorCode);
MCI_STATUS_PARMS sp2 = (MCI_STATUS_PARMS)Marshal.PtrToStructure(spPointer, typeof(MCI_STATUS_PARMS));
return(new TimeSpan(0, 0, 0, 0, (Int32)sp2.dwReturn));
}
finally
{
Marshal.FreeHGlobal(spPointer);
}
}
else
{
throw new InvalidOperationException("Sound device has already closed.");
}
}
/// <summary>
/// 获取播放状态
/// </summary>
/// <returns></returns>
public SoundPlayerState GetState()
{
if (m_DeviceID != 0)
{
MCI_STATUS_PARMS sp = new MCI_STATUS_PARMS();
sp.dwCallback = IntPtr.Zero;
sp.dwItem = MCI_Status.MCI_STATUS_MODE;
IntPtr spPointer = Marshal.AllocHGlobal(Marshal.SizeOf(sp));
try
{
Marshal.StructureToPtr(sp, spPointer, false);
UInt32 errorCode = mciSendCommand(m_DeviceID, (UInt32)MCI_Command.MCI_STATUS, (UInt32)(MCI_StatusFlags.MCI_WAIT | MCI_StatusFlags.MCI_STATUS_ITEM), spPointer);
CheckError(errorCode);
MCI_STATUS_PARMS sp2 = (MCI_STATUS_PARMS)Marshal.PtrToStructure(spPointer, typeof(MCI_STATUS_PARMS));
switch (sp2.dwReturn)
{
case MCI_Mode.MCI_MODE_NOT_READY:
return(SoundPlayerState.NotReady);
case MCI_Mode.MCI_MODE_OPEN:
return(SoundPlayerState.Open);
case MCI_Mode.MCI_MODE_PAUSE:
return(SoundPlayerState.Pause);
case MCI_Mode.MCI_MODE_PLAY:
return(SoundPlayerState.Play);
case MCI_Mode.MCI_MODE_RECORD:
return(SoundPlayerState.Record);
case MCI_Mode.MCI_MODE_SEEK:
return(SoundPlayerState.Seek);
default:
return(SoundPlayerState.Stop);
}
}
finally
{
Marshal.FreeHGlobal(spPointer);
}
}
else
{
throw new InvalidOperationException("Sound device has already closed.");
}
}
private int GetStatus(int item)
{
int err = 0;
StringBuilder buf = new StringBuilder(1000);
if (deviceID > 0)
{
MCI_STATUS_PARMS mcistatusparms = new MCI_STATUS_PARMS();
mcistatusparms.dwItem = item;
mcistatusparms.dwReturn = 0;
err = mciSendCommandA(deviceID, MCI_STATUS, MCI_WAIT | MCI_STATUS_ITEM, ref mcistatusparms);
if (err != 0)
{
mciGetErrorStringA(err, buf, 1000);
//throw new ApplicationException("获取播放状态出错，" + buf.ToString());
}
return mcistatusparms.dwReturn;
}
return -1;
}
/// <summary>
/// 获取 trackNum 音轨的长度（驱动类型为 CDAudio 或 VideoDisc）。
/// </summary>
/// <param name="trackNum">音轨数。</param>
/// <returns>trackNum 音轨的长度（MSF格式）。</returns>
public int GetTrackLength(int trackNum)
{
int err = 0;
StringBuilder buf = new StringBuilder(1000);
if (deviceID > 0 && timeFormat == TimeFormat.TMSF)
{
MCI_STATUS_PARMS mcistatusparms = new MCI_STATUS_PARMS();
mcistatusparms.dwItem = MCI_STATUS_LENGTH;
mcistatusparms.dwTrack = trackNum;
mcistatusparms.dwReturn = 0;
err = mciSendCommandA(deviceID, MCI_STATUS, MCI_WAIT | MCI_STATUS_ITEM | MCI_TRACK, ref mcistatusparms);
if (err != 0)
{
mciGetErrorStringA(err, buf, 1000);
//throw new ApplicationException("获取播放状态出错，" + buf.ToString());
}
return mcistatusparms.dwReturn;
}
return 0;
}
private static extern int mciSendCommandStatus(int wDeviceID, int uMessage, int dwParam1, ref MCI_STATUS_PARMS dwParam2);
private static extern int mciSendCommandA(
Int32 wDeviceID,
UInt32 uMessage,
Int32 dwParam,
ref MCI_STATUS_PARMS Any);
