( [out, size_is(ulBufSize)] LPSTR pRoot,    // pointer to buffer to get root string
      [in]  ULONG ulBufSize,                    // size of buffer passed in
      [out] ULONG *pulActualSize                // size of actual data returned
    );
}

//==========================================================================
//==========================================================================
// IDvdCmd interface -- the IDVDControl2 command sequencing object.
//
// For the IDVDControl2 interface, the application can track the status of
// commands that have been issued to the navigator.  Each command is identified
// by an IDvdCmd object.  The IDvdCmd object stores the results of the command
// at both the start (when the command has begun processing) and the end after
// it has completed.  It also allows the app to synchronize with the processing
// of the command.
//
//  The command object also allows the app to uniquely identify and correlate
// completion events (if it prefers to process events in a message loop instead
// of creating another process).
//
//     Allows the app to track the status of an issued command to the nav.
//==========================================================================
//==========================================================================

[
object,
uuid(5a4a97e4-94ee-4a55-9751-74b5643aa27d),
pointer_default(unique)
]

interface IDvdCmd : IUnknown {
    import "unknwn.idl";

    //
    // WaitForStart
    //
    // Blocks the application until the command has begun.
    //
    HRESULT WaitForStart();

    //
    // WaitForEnd
    //
    // Blocks until the command has completed or has been cancelled.
    HRESULT WaitForEnd();
}

//==========================================================================
//==========================================================================
// IDvdState interface -- the State state object.
//
// Whenever the application wishes to save or restore a location on the disc,
// it needs to store the DVD state into an object.
// The State object supports the IPersistStream  
//
//==========================================================================
//==========================================================================

[
object,
uuid(86303d6d-1c4a-4087-ab42-f711167048ef),
pointer_default(unique)
]

interface IDvdState : IUnknown
{
    //
    // GetDiscID
    //
    // Returns the disc ID from which the bookmark was made.
    //
    HRESULT GetDiscID
    ( [out] ULONGLONG* pullUniqueID ); // 64-bit unique id for the disc

    //
    // GetParentalLevel
    //
    // Returns the state's parental level
    //
    HRESULT GetParentalLevel
    ( [out] ULONG* pulParentalLevel );
}

//==========================================================================
//==========================================================================
// IDvdControl2 interface -- Basic DVD-Video playback control.
// This is modeled after the app control of a player specified in Annex J 
// of the DVD Video spec.  IDvdInfo2 can be used to get information useful
// in using IDvdControl2
//==========================================================================
//==========================================================================

[
object,
uuid(33BC7430-EEC0-11D2-8201-00A0C9D74842),
pointer_default(unique)
]

interface IDvdControl2 : IUnknown {
    import "unknwn.idl";
    
    // PlayTitle
    //
    // Start playing from the beginning of the specified title number.
    // Annex J: Title_Play
    // Title numbers range between 1 and 99.
    HRESULT PlayTitle
    ( [in]  ULONG   ulTitle,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd 
    );

    // PlayChapterInTitle
    //
    // Start playing from the beginning of the given chapter (or part-of-title) number
    // within the specified title number.
    // Annex J: PTT_Play
    // Title numbers range between 1 and 99.
    // Chapters range from 1 to 999.
    HRESULT PlayChapterInTitle
    ( [in]  ULONG   ulTitle, 
      [in]  ULONG   ulChapter,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd 
    );

    // PlayAtTimeInTitle
    //
    // Start playing from the specified time within the specified title number.
    // NOTE: the actual start time will be the closest sync point before
    // or equal to the specified frame number.
    // Annex J: Time_Play
    // Title numbers range between 1 and 99.
    HRESULT PlayAtTimeInTitle
    ( [in]  ULONG   ulTitle,
      [in]  DVD_HMSF_TIMECODE*   pStartTime,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd 
    );

    // Stop
    // Stop playback by transferring DVD Navigator to the DVD "Stop State" (same 
    // as DVD_DOMAIN_Stop), but filter graph remains in DirectShow's Run state.
    // Annex J: Stop
    HRESULT Stop();

    // ReturnFromSubmenu
    //
    // Stop playback of current program chain (PGC) and start playing the PGC 
    // specified by "GoUp_PGCN".in the PGCI.
    // If the GoUp_PGCN value is 0xFFFF the Resume() operation is carried out.
    // Annex J: GoUp
    HRESULT ReturnFromSubmenu(
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd );

    // PlayAtTime
    // Start playing at the specified time within the current title.
    // NOTE: the actual start time will be the closest sync point before
    // or equal to the specified frame number.
    // Annex J: Time_Search
    // The time is in BCD format, passed in as a ULONG.
    HRESULT PlayAtTime
    ( [in]  DVD_HMSF_TIMECODE* pTime,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd 
    );

    // PlayChapter
    // Start playing at the specified chapter (or part-of-title) within
    // the current title.
    // Annex J: PTT_Search
    // Chapters range from 1 to 999.
    HRESULT PlayChapter
    ( [in]  ULONG   ulChapter,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd 
    );

    // PlayPrevChapter
    // Start playing at the beginning of the previous DVD "program".
    // For One-Sequential_PGC_Titles (which includes most titles) a program 
    // is equivalent to a chapter, otherwise a program is part of a chapter. 
    // Annex J: PrevPG_Search
    HRESULT PlayPrevChapter(
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd );

    // ReplayChapter
    // Start playing from the beginning of they current program.
    // Annex J: TopPG_Search
    HRESULT ReplayChapter(
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd );

    // PlayNextChapter
    // Start playing from the beginning of the next program.
    // Annex J: NextPG_Search
    HRESULT PlayNextChapter(
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd );

    // PlayForwards
    // Set forward play at the specified speed.  
    // Annex J: Forward_Scan
    //      dSpeed == 1 is normal play
    //      dSpeed  < 1 is slow play
    //      dSpeed  > 1 is fast play
    // For dSpeed != 1, audio and subpicture is muted.
    HRESULT PlayForwards
    ( [in]  double  dSpeed,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd
    );

    // PlayBackwards
    // Set reverse play at the specified speed.  
    // Annex J: Backward_Scan
    //      dSpeed == 1 is normal play speed in reverse
    //      dSpeed  < 1 is slow play in reverse
    //      dSpeed  > 1 is fast play in reverse
    // For reverse play, audio and subpicture are always muted.
    HRESULT PlayBackwards
    ( [in]  double  dSpeed,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd
    );

    // ShowMenu
    // Start playback of the Menu specified by an enum DVD_MENU_ID.
    // Annex J: Menu_Call
    HRESULT ShowMenu
    ( [in]  DVD_MENU_ID   MenuID,
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd  
    );

    // Resume
    // Returns to title playback in DVD_DOMAIN_Title. This is typically
    // done after MenuCall which puts the DVD Navigator in 
    // DVD_DOMAIN_VideoTitleSetMenu or DVD_DOMAIN_VideoManagerMenu.
    // Annex J: Resume
    HRESULT Resume(
      [in]  DWORD   dwFlags,  
      [out] IDvdCmd** ppCmd );

    // SelectRelativeButton
    // Moves the selection highlight above, below, to the left of, or to the right of the
    // currently selected.
    // "Selecting" a DVD button simply highlights the button but does
    // not "Activate" the button.  Selecting is the Windows equivalent 
    // to tabbing to a button but not pressing the space bar or enter key.
    // Activating is the Windows equivalent of pressing the space bar or
    // enter key after tabbing to a button.
    // Annex J: Upper_button_Select, Lower_button_Select, Left_button_Select, Right_button_Select
    HRESULT SelectRelativeButton( DVD_RELATIVE_BUTTON buttonDir );

    // ActivateButton
    // Activates current button.
    // Annex J: Button_Activate
    HRESULT ActivateButton();

    // SelectButton
    // Selects a specific button (with the index from 1 to 36).
    // ulButton is intended to be a number entered by a user corresponding
    // to button numbers currently displayed on screen.  
    // Button numbers range from 1 to 36.
    HRESULT SelectButton
    ( [in]  ULONG   ulButton
    );

    // SelectAndActivateButton
    // Selects and then activates the button specified by the user.  
    // ulButton is intended to be a number entered by a user corresponding
    // to button numbers currently displayed on screen.  
    // Annex J: Button_Select_And_Activate
    // Button numbers range from 1 to 36.
    HRESULT SelectAndActivateButton
    ( [in]  ULONG   ulButton
    );

    // StillOff
    // Releases any current still if there are no available buttons.
    // This includes VOBU stills, Cell stills, and PGC stills, whether the 
    // still is infinite.  When buttons are available, stills are released by
    // activating a button.  Note this does not release a Pause.
    // Annex J: Still_Off
    HRESULT StillOff();

    // Pause
    // Freezes / unfreezes playback and any internal timers. This is similar to
    // IMediaControl::Pause(), but not the same in effect as IMediaControl::Pause
    // puts the filter (all filters, if done to the graph) in paused state.
    // Annex J: Pause_On and Pause_Off
    // bState is TRUE or FALSE to indicate whether to do Puase_on/Pause_Off according
    // to Annex J terminology.
    HRESULT Pause
    ( [in]  BOOL   bState
    );

    // SelectAudioStream
    // Changes the current audio stream to ulAudio.
    // Annex J: Audio_Stream_Change
    // Audio stream number ranges between 0 and 7 or DEFAULT_AUDIO_STREAM (15 - default based on default language & language extension)
    HRESULT SelectAudioStream
    ( [in]  ULONG   ulAudio,
      [in]  DWORD dwFlags,  
      [out] IDvdCmd** ppCmd 

    );

    // SelectSubpictureStream
    // Changes the current subpicture stream number to ulSubPicture
    // Annex J: Sub-picture_Stream_Change (first param)
    // Subpicture stream number should be between 0 and 31 or 63.
    HRESULT SelectSubpictureStream
    ( [in]  ULONG   ulSubPicture,
      [in]  DWORD dwFlags,  
      [out] IDvdCmd** ppCmd 

    );

    // SetSubpictureState
    // Turns on/off current subpicture stream display.
    // Annex J: Sub-picture_Stream_Change (second param)
    // Subpicture state is On or Off (TRUE or FALSE)
    HRESULT SetSubpictureState
    ( [in]  BOOL    bState,
      [in]  DWORD dwFlags,  
      [out] IDvdCmd** ppCmd
    );

    // SelectAngle
    // Changes the current angle number.
    // Annex J: Angle_Change