
   X-Video Motion Compensation - API specification v. 1.0

   Mark Vojkovich <markv@xfree86.org>


/* history */

   first draft (9/6/00)
   second draft (10/31/00) - Changed to allow acceleration at both
      the motion compensation and IDCT level.
   third draft (1/21/01) - Some refinements and subpicture support.
   fourth draft (5/2/01) - Dual Prime clarification, add
      XvMCSetAttribute.
   fifth draft (6/26/01) - Change definition of XvMCCompositeSubpicture
      plus some clarifications and fixed typographical errors.
   sixth draft (9/24/01) - Added XVMC_SECOND_FIELD and removed 
      XVMC_PROGRESSIVE_FRAME and XVMC_TOP_FIELD_FIRST flags.
   seventh draft (10/26/01) - Added XVMC_INTRA_UNSIGNED option.
   eighth draft (11/13/02) - Removed IQ level acceleration and
      changed some structures to remove unused fields.

/* acknowledgements */

   Thanks to Matthew J. Sottek from Intel for lots of input.

/********************************************************************/

      OVERVIEW

/********************************************************************/

     XvMC extends the X-Video extension (Xv) and makes use of the
  familar concept of the XvPort.  Ports have attributes that can be set 
  and queried through Xv.  In XvMC ports can also have hardware motion
  compensation contexts created for use with them.  Ports which support 
  XvImages (ie. they have an "XV_IMAGE" port encoding as described in 
  the Xv version 2.2 API addendum) can be queried for the list of XvMCSurface
  types they support.  If they support any XvMCSurface types an 
  XvMCContext can be created for that port.

     An XvMCContext describes the state of the motion compensation
  pipeline.  An individual XvMCContext can be created for use with
  a single port, surface type, motion compensation type, width and
  height combination.  For example, a context might be created for a
  particular port that does MPEG-2 motion compensation on 720 x 480
  4:2:0 surfaces.  Once the context is created, referencing it implies 
  the port, surface type, size and the motion compensation type.  Contexts
  may be "direct" or "indirect".  For indirect contexts the X server
  renders all video using the data passed to it by the client.  For
  direct contexts the client libraries render the video with little
  or no interaction with the X server.

     XvMCSurfaces are buffers into which the motion compensation
  hardware can render.  The data in the buffers themselves are not client
  accessible and may be stored in a hardware-specific format.  Any
  number of buffers can be created for use with a particular context
  (resources permitting).

     XvMC provides video acceleration starting at one of two places
  in the video pipeline.  Acceleration starting at the first point,
  which we shall call the "Motion Compensation" level, begins after the
  the inverse quantization and IDCT at the place where motion compensation
  is to be applied.  The second point, which we shall call the "IDCT" 
  level, begins before the IDCT just after the inverse quantization.

     Rendering is done by presenting the library with a target XvMCSurface
  and up to two reference XvMCSurfaces for the motion compensation, a 
  buffer of 8x8 blocks and a command buffer which describes how to
  use the 8x8 blocks along with motion compensation vectors to construct
  the data in the target XvMCSurface.  When the pipeline starts at the
  IDCT level, Xv will perform the IDCT on the blocks before performing
  the motion compensation. A function is provided to copy/overlay a
  portion of the XvMCSurface to a drawable with arbitrary scaling.

    XvMCSubpictures are separate surfaces that may be blended with the
  target surface.  Any number of XvMCSubpictures may be created for use
  with a context (resources permitting).  Both "backend" and "frontend"
  subpicture behavior are supported.

/********************************************************************/

          QUERYING THE EXTENSION 

/********************************************************************/

/* Errors */
#define XvMCBadContext		0
#define XvMCBadSurface		1
#define XvMCBadSubpicture	2

Bool XvMCQueryExtension (Display *display, int *eventBase, int *errBase)

   Returns True if the extension exists, False otherwise.  Also returns
 the error and event bases.

   display - The connection to the server.

   eventBase -
   errBase -  The returned event and error bases.  Currently there
              are no events defined.

Status XvMCQueryVersion (Display *display, int *major, int *minor)

   Query the major and minor version numbers of the extension.

   display - The connection to the server.

   major -
   minor -  The returned major and minor version numbers.

/********************************************************************/

          QUERYING SURFACE TYPES

/********************************************************************/

/* Chroma formats */
#define XVMC_CHROMA_FORMAT_420		0x00000001
#define XVMC_CHROMA_FORMAT_422		0x00000002
#define XVMC_CHROMA_FORMAT_444		0x00000003

/* XvMCSurfaceInfo Flags */
#define XVMC_OVERLAID_SURFACE			0x00000001
#define XVMC_BACKEND_SUBPICTURE			0x00000002
#define XVMC_SUBPICTURE_INDEPENDENT_SCALING	0x00000004
#define XVMC_INTRA_UNSIGNED                     0x00000008

/* Motion Compensation types */
#define XVMC_MOCOMP			0x00000000
#define XVMC_IDCT			0x00010000

#define	XVMC_MPEG_1			0x00000001
#define XVMC_MPEG_2			0x00000002
#define XVMC_H263			0x00000003
#define XVMC_MPEG_4			0x00000004


typedef struct {
   int surface_type_id;
   int chroma_format;
   unsigned short max_width;       
   unsigned short max_height;	
   unsigned short subpicture_max_width;
   unsigned short subpicture_max_height;
   int mc_type;  	
   int flags;
} XvMCSurfaceInfo;

   surface_type_id - Unique descriptor for this surface type.

   chroma_format - Chroma format of this surface (eg. XVMC_CHROMA_FORMAT_420, 
		XVMC_CHROMA_FORMAT_422, XVMC_CHROMA_FORMAT_444).

   max_width -
   max_height -  Maximum dimensions of the luma data in pixels.

   subpicture_max_width -
   subpicture_max_height -  The Maximum dimensions of the subpicture 
                            that can be created for use with this surface
                            Both fields are zero if subpictures are not
                            supported.

   mc_type -  The type of motion compensation available for this
              surface.  This consists of XVMC_MPEG_1, XVMC_MPEG_2, XVMC_H263
              or XVMC_MPEG_4 OR'd together with any of the following:

                 XVMC_MOCOMP - Acceleration starts at the motion compensation
                               level;

                 XVMC_IDCT - Acceleration starts at the IDCT level.
               
   flags -  Any combination of the following may be OR'd together.

	XVMC_OVERLAID_SURFACE - Displayed data is overlaid and not
	                        physically in the visible framebuffer.
                                When this is set the client is responsible
                                for painting the colorkey.

	XVMC_BACKEND_SUBPICTURE - The supicture is of the "backend" 
                                  variety.  It is "frontend" otherwise.
                                  There is more information on this in the
                                  section on subpictures below.

	XVMC_SUBPICTURE_INDEPENDENT_SCALING - The subpicture can be scaled
                                              independently of the video
                                              surface.  See the section on
                                              subpictures below.

        XVMC_INTRA_UNSIGNED - When this flag is set, the motion compenstation
                              level Intra macroblock data should be in an
                              unsigned format rather than the signed format
                              present in the mpeg stream.  This flag applies
                              only to motion compensation level acceleration.

XvMCSurfaceInfo * XvMCListSurfaceTypes(Display *dpy, XvPortID port, int *num)

   Returns the number of surface types supported by the XvPort and an array 
   of XvMCSurfaceInfo describing each surface type.  The returned array 
   should be freed with XFree().

   dpy -  The connection to the server.

   port - The port we want to get the XvMCSurfaceInfo array for.

   num  - The number of elements returned in the array.

   Errors:

      XvBadPort -  The requested port does not exist.

      BadAlloc - There are insufficient resources to complete this request.


/********************************************************************/

          CREATING A CONTEXT

/********************************************************************/

/* XvMCContext flags */
#define XVMC_DIRECT			0x00000001

typedef struct {
   XID context_id;
   int surface_type_id;
   unsigned short width;
   unsigned short height;
   XVPortID port;
   int flags;
   void * privData;  /* private to the library */
} XvMCContext;

   context_id - An XID associated with the context.

   surface_type_id - This refers to the XvMCSurfaceInfo that describes
                     the surface characteristics.
   
   width -
   height -  The dimensions (of the luma data) this context supports.

   port -  The port that this context supports.

   flags -  Any combination may be OR'd together.

	XVMC_DIRECT -  This context is direct rendered.


Status XvMCCreateContext (
   Display display,
   XVPortID port,
   int surface_type_id,
   int width,
   int height,
   int flags,
   XvMCContext * context
);

   This creates a context by filling out the XvMCContext structure passed 
   to it and returning Success.

   display -  Specifies the connection to the server.

   port -  Specifies the port to create the context for.

   surface_type_id -
   width -
   height -  Specifies the surface type and dimensions that this
             context will be used for.  The surface_type_id corresponds
             to the surface_type_id referenced by the XvMCSurfaceInfo.
	     The surface returned may be larger than the surface requested
             (usually the next larger multiple of 16x16 pixels).

   flags -  Any of the following may by OR'd together:

	 XVMC_DIRECT -  A direct context is requested.
                        If a direct context cannot be created the request
                        will not fail, rather, an indirect context will 
			be created instead.
    
   context - Pointer to the pre-allocated XvMCContext structure.
 


   Errors:

      XvBadPort -  The requested port does not exist.

      BadValue -  The dimensions requested are not supported by the
                  surface type.

      BadMatch -  The surface_type_id is not supported by the port.

      BadAlloc -  There are not sufficient resources to fulfill this
                  request.


Status XvMCDestroyContext (Display display, XvMCContext * context)

     Destroys the specified context.  

      display - Specifies the connection to the server.

      context - The context to be destroyed.

     Errors:    

       XvMCBadContext - The XvMCContext is not valid.


/*********************************************************************/

          SURFACE CREATION

/*********************************************************************/

typedef struct {
  XID surface_id;	   
  XID context_id;
  int surface_type_id;
  unsigned short width;
  unsigned short height;
  void *privData;  /* private to the library */
} XvMCSurface;

  surface_id -  An XID associated with the surface.

  context_id -  The XID of the context for which the surface was created.

  surface_type_id - Derived from the context_id, it specifies the
                    XvMCSurfaceInfo describing the surface.

  width -
  height -  The width and height of the luma data.


Status 
XvMCCreateSurface(
  Display *display,
  XvMCContext * context;
  XvMCSurface * surface;
);

     Creates a surface (Frame) for use with the specified context.  
   The surface structure is filled out and Success is returned if no
   error occured.

   context - pointer to a valid context.  The context implies
             the surface type to be created, and its dimensions.

   surface - pointer to a pre-allocated XvMCSurface structure.

   Errors:

	XvMCBadContext - the context is not valid.

        BadAlloc - there are insufficient resources to complete 
                   this operation.

Status XvMCDestroySurface(Display *display, XvMCSurface *surface);

   Destroys the given surface.

    display - Specifies the connection to the server.

    surface - The surface to be destroyed.

    Errors:

       XvMCBadSurface - The XvMCSurface is not valid.



/*********************************************************************/

    RENDERING A FRAME

/*********************************************************************/

typedef struct {
  XID context_id;
  unsigned int num_blocks;
  short *blocks;
  void *privData;	/* private to the library */
} XvMCBlockArray;

   num_blocks - Number of 64 element blocks in the blocks array.

   context_id - XID of the context these blocks were allocated for.

   blocks -  Pointer to an array of (64 * num_blocks) shorts.

Status XvMCCreateBlocks (
    Display *display, 
    XvMCContext *context,
    unsigned int num_blocks,
    XvMCBlockArray * block
);

   This allocates an array of DCT blocks in the XvMCBlockArray
   structure passed to it.  Success is returned if no error occured.

    display - The connection to the server.

    context -  The context the block array is being created for.

    num_blocks - The number of 64 element short blocks to be allocated.
                 This number must be non-zero.

    block -  A pointer to a pre-allocated XvMCBlockArray structure.
                
      Errors: 

	  XvMCBadContext - the context is invalid.

          BadAlloc -  There are insufficient resources to complete the 
                      operation.

          BadValue -  num_blocks was zero.

Status XvMCDestroyBlocks (Display *display, XvMCBlockArray * block)

   Frees the given array.

     display -  The connection to the server.

     block - The block array to be freed.


   ----------------------------------------------------------

#define XVMC_MB_TYPE_MOTION_FORWARD	0x02
#define XVMC_MB_TYPE_MOTION_BACKWARD	0x04
#define XVMC_MB_TYPE_PATTERN		0x08
#define XVMC_MB_TYPE_INTRA		0x10

#define XVMC_PREDICTION_FIELD		0x01
#define XVMC_PREDICTION_FRAME		0x02
#define XVMC_PREDICTION_DUAL_PRIME	0x03
#define XVMC_PREDICTION_16x8		0x02 
#define XVMC_PREDICTION_4MV		0x04

#define XVMC_SELECT_FIRST_FORWARD	0x01
#define XVMC_SELECT_FIRST_BACKWARD	0x02
#define XVMC_SELECT_SECOND_FORWARD	0x04
#define XVMC_SELECT_SECOND_BACKWARD	0x08

#define XVMC_DCT_TYPE_FRAME		0x00
#define XVMC_DCT_TYPE_FIELD		0x01

typedef struct {
   unsigned short x;
   unsigned short y;
   unsigned char macroblock_type;
   unsigned char motion_type;   
   unsigned char motion_vertical_field_select;
   unsigned char dct_type;
   short PMV[2][2][2];
   unsigned int index;
   unsigned short coded_block_pattern;
   unsigned short pad0;
} XvMCMacroBlock;

    x, y -  location of the macroblock on the surface in units of macroblocks.

    macroblock_type - can be any of the following flags OR'd together:

	XVMC_MB_TYPE_MOTION_FORWARD - Forward motion prediction should
                                      be done.  This flag is ignored for
				      Intra frames.

	XVMC_MB_TYPE_MOTION_BACKWARD - Backward motion prediction should
                                       be done.  This flag is ignored when
				       the frame is not bidirectionally
                                       predicted.

        XVMC_MB_TYPE_PATTERN -  Blocks are referenced and they contain 
                                differentials.  The coded_block_pattern will
                                indicate the number of blocks and index will
                                note their locations in the block array.

	XVMC_MB_TYPE_INTRA -  Blocks are referenced and they are intra blocks. 
                              The coded_block_pattern will indicate the number
                              of blocks and index will note their locations in 
                              the block array.  XVMC_MB_TYPE_PATTERN and
                              XVMC_MB_TYPE_INTRA are mutually exclusive.  If
                              both are specified, XVMC_MB_TYPE_INTRA takes
                              precedence.

    motion_type -  If the surface is a field, the following are valid:
			XVMC_PREDICTION_FIELD
			XVMC_PREDICTION_16x8
			XVMC_PREDICTION_DUAL_PRIME
		   If the surface is a frame, the following are valid:
			XVMC_PREDICTION_FIELD
			XVMC_PREDICTION_FRAME
			XVMC_PREDICTION_DUAL_PRIME

    motion_vertical_field_select - The following flags may be OR'd together

		XVMC_SELECT_FIRST_FORWARD
		XVMC_SELECT_FIRST_BACKWARD
		XVMC_SELECT_SECOND_FORWARD
		XVMC_SELECT_SECOND_BACKWARD
              
              If the bit is set the bottom field is indicated.
              If the bit is clear the top field is indicated.

              X X X X D C B A
              ------- | | | |_  First vector forward
                |     | | |___  First vector backward
              unused  | |_____ Second vector forward
                      |_______ Second vector backward

    PMV -  The motion vector(s)
             
               PMV[c][b][a]

                  a - This holds the vector. 0 = horizontal, 1 = vertical.
                  b - 0 = forward, 1 = backward.
                  c - 0 = first vector, 1 = second vector.

	    The motion vectors are used only when XVMC_MB_TYPE_MOTION_FORWARD
            or XVMC_MB_TYPE_MOTION_BACKWARD are set.

            DualPrime vectors must be fully decoded and placed in the PMV
            array as follows. 

            Field structure:

                vector[0][0][1:0] -> PMV[0][0][1:0]
                vector[2][0][1:0] -> PMV[0][1][1:0]

            Frame structure:
 
                vector[0][0][1:0] -> PMV[0][0][1:0]  top from top
                vector[0][0][1:0] -> PMV[0][1][1:0]  bottom from bottom
                vector[2][0][1:0] -> PMV[1][0][1:0]  top from bottom
                vector[3][0][1:0] -> PMV[1][1][1:0]  bottom from top


    index -  The offset in units of (64 * sizeof(short)) from the start of
             the block array where this macroblock's DCT blocks, as indicated
             by the coded_block_pattern, are stored.

    coded_block_pattern - Indicates the blocks to be updated.  The bitplanes
                          are specific to the mc_type of the surface.  This
                          field is valid only if XVMC_MB_TYPE_PATTERN or 
                          XVMC_MB_TYPE_INTRA are set.  In that case the blocks
                          are differential or intra blocks respectively.
			  The bitplanes are described in ISO/IEC 13818-2
			  Figures 6.10-12.

    dct_type -  This field indicates whether frame pictures are frame DCT
                coded or field DCT coded. ie XVMC_DCT_TYPE_FIELD or
                XVMC_DCT_TYPE_FRAME.


typedef struct {
  unsigned int num_blocks;
  XID context_id;
  XvMCMacroBlock *macro_blocks;
  void *privData;	/* private to the library */
} XvMCMacroBlockArray;


   num_blocks - Number of XvMCMacroBlocks in the macro_blocks array.

   context_id - XID of the context these macroblocks were allocated for.

   macro_blocks -  Pointer to an array of num_blocks XvMCMacroBlocks.


Status XvMCCreateMacroBlocks (
    Display *display, 
    XvMCContext *context,
    unsigned int num_blocks,
    XvMCMacroBlockArray * blocks
);

   This allocates an array of XvMCMacroBlocks in the XvMCMacroBlockArray
   structure passed to it.  Success is returned if no error occured.

    display - The connection to the server.

    context -  The context the macroblock array is being created for.

    num_blocks - The number of XvMCMacroBlocks to be allocated.
                 This number must be non-zero.

    blocks -  A pointer to a pre-allocated XvMCMacroBlockArray structure.
                
      Errors: 

	  XvMCBadContext - the context is invalid.

          BadAlloc -  There are insufficient resources to complete the 
                      operation.

          BadValue -  num_blocks was zero.

Status XvMCDestroyMacroBlocks (Display *display, XvMCMacroBlockArray * block)

   Frees the given array.

    display - The connection to the server.

    block -  The macro block array to be freed.

 
    ------------------------------------------------------------

#define XVMC_TOP_FIELD		0x00000001
#define XVMC_BOTTOM_FIELD	0x00000002
#define XVMC_FRAME_PICTURE	(XVMC_TOP_FIELD | XVMC_BOTTOM_FIELD)

#define XVMC_SECOND_FIELD       0x00000004

Status XvMCRenderSurface(
    Display *display,
    XvMCContext *context,
    unsigned int picture_structure,
    Surface *target_surface,
    Surface *past_surface,
    Surface *future_surface,
    unsigned int flags,
    unsigned int num_macroblocks,
    unsigned int first_macroblock,
    XvMCMacroBlockArray *macroblock_array,
    XvMCBlockArray *blocks
);

    This function renders the macroblocks passed to it.  It will not
    return until it has read all of the macroblocks, however, rendering 
    will usually not be completed by that time.  The return of this
    function means it is safe to touch the blocks and macroblock_array.
    To synchronize rendering see the section on sychronization below.

    display - The connection to the server.

    context - The context used to render.

    target_surface -
    past_surface -
    furture_surface -

        The target_surface is required.  If the future and past 
      surfaces are NULL, the target_surface is an "Intra" frame.

      	If the past surface is provided but not the future surface,
      the target_surface is a "Predicted Inter" frame.

	If both past and future surfaces are provided, the
      target_surface is a "Bidirectionally-predicted Inter" frame.

        Specifying a future surface without a past surface results
      in a BadMatch.

      All surfaces must belong to the same context.

    picture_structure - XVMC_TOP_FIELD, XVMC_BOTTOM_FIELD or
                        XVMC_FRAME_PICTURE.


    flags -  Flags may include:

            XVMC_SECOND_FIELD - For field pictures this indicates whether
                                the current field (top or bottom) is first 
                                or second in the sequence.

    num_macroblocks -  The number of XvMCMacroBlock structures to execute in
                       the macroblock_array.

    first_macroblock - The index of the first XvMCMacroBlock to process in the
                       macroblock_array.

    blocks - The array of XvMCBlocks to be referenced by the XvMCMacroBlocks.
             The data in the individual blocks are in raster scan order and
             should be clamped to the limits specific to the acceleration
             level.  For motion compensation level acceleration this is 8
             bits for Intra and 9 bits for non-Intra data.  At the IDCT level
             this is 12 bits.

  Errors:

        XvMCBadContext - The context is not valid.
    
        XvMCBadSurface - Any of the surfaces are not valid. 

	BadMatch - Any of the surfaces do not belong to the specified
                   context or a future surface was specified without
                   a past surface.

        BadValue - Unrecognized data for the picture_structure.


/***********************************************************************/

     DISPLAYING THE SURFACE

/***********************************************************************/


Status
XvMCPutSurface(
  Display *display,
  XvMCSurface *surface,
  Drawable draw,
  short srcx, 
  short srcy, 
  unsigned short srcw, 
  unsigned short srch,
  short destx,
  short desty,
  unsigned short destw,
  unsigned short desth,
  int flags
);

   Display the rectangle from the source defined by srcx/y/w/h scaled
 to destw by desth and placed at (destx, desty) on the given drawable.
 This function is not guaranteed to be pipelined with previous rendering 
 commands and may display the surface immediately.  Therefore, the client
 must query that the surface has finished rendering before calling this
 function.

    display - The connection to the server.

    surface - The surface to copy/overlay from.

    draw - The drawable to copy/overlay the video on. 

    srcx -
    srcy -
    srcw -
    srch -  The rectangle in the source area from the surface that is
            to be displayed.

    destx -
    desty -
    destw -
    desth -  The rectangle in the destination drawable where the scaled 
             source rectangle should be displayed. 

    flags - this indicates the field to be displayed and can be XVMC_TOP_FIELD,
            XVMC_BOTTOM_FIELD or XVMC_FRAME_PICTURE.  XVMC_FRAME_PICTURE
            displays both fields (weave).

   Errors:

       XvMCBadSurface - The surface is not valid.

       BadDrawable -  The drawable does not exist.


Status XvMCHideSurface(Display *display, XvMCSurface *surface)

   Stops display of a surface.  This is only needed if the surface is an
   overlaid surface as indicated in the XvMCSurfaceInfo - it is a no-op
   otherwise.  

     display - The connection to the server.
 
     surface - The surface to be hidden.
  
      Errors:
	
	  XvMCBadSurface - The surface is not valid.


/***********************************************************************/

     COMPOSITING THE SUBPICTURE

/***********************************************************************/


XvImageFormatValues * XvMCListSubpictureTypes (
  Display * display,
  XvPortID port,
  int surface_type_id,
  int *count_return
)

  Returns an array of XvImageFormatValues supported by the surface_type_id
  describing the surface. The surface_type_id is acquired from the
  XvMCSurfaceInfo.  This list should be freed with XFree().

   display - Specifies the connection to the X-server.

   port - Specifies the port we are interested in.
   
   surface_type_id - Specifies the surface type for which we want to 
                     query the supported subpicture types. 
                    
   count_return - the size of the returned array.

   Errors:

      BadPort -  The port doesn't exist.
  
      BadAlloc - There are insufficient resources to complete this request.
 
      BadMatch - The surface type is not supported on that port. 
  

typedef struct {
  XID subpicture_id;
  XID context_id;
  int xvimage_id;
  unsigned short width;
  unsigned short height;
  int num_palette_entries;
  int entry_bytes;
  char component_order[4];
  void *privData;    /* private to the library */
} XvMCSubpicture;

   
   subpicture_id - An XID associated with this subpicture.

   context_id - The XID of the context this subpicture was created for.

   xvimage_id - The id descriptor of the XvImage format that may be used
                with this subpicture.

   width -
   height - The dimensions of the subpicture.

   num_palette_entries - For paletted formats only.  This is the number
                         of palette entries.  It is zero for XvImages
                         without palettes.
  
   entry_bytes -  Each component is one byte and entry_bytes indicates
                  the number of components in each entry (eg. 3 for
                  YUV palette entries).  This field is zero when 
                  palettes are not used. 

   component_order - Is an array of ascii characters describing the order
                     of the components within the bytes.  Only entry_bytes
                     characters of the string are used. 

Status
XvMCCreateSubpicture (
   Display *display, 
   XvMCContext *context,
   XvMCSubpicture *subpicture, 
   unsigned short width,
   unsigned short height,
   int xvimage_id
)

   This creates a subpicture by filling out the XvMCSubpicture structure
   passed to it and returning Success.

    display -  Specifies the connection to the X-Server.
  
    context -  The context to create the subpicture for.

    subpicture - Pre-allocated XvMCSubpicture structure to be filled 
                 out by this function.

    width -
    height -  The dimensions of the subpicture.
    
    xvimage_id - The id describing the XvImage format.


    Errors:

      BadAlloc - There are insufficient resources to complete this request.

      XvMCBadContext - The specified context does not exist.

      BadMatch - The XvImage format id specified is not supported by
                 the context. 

      BadValue - If the size requested is larger than the max size reported
                 in the XvMCSurfaceInfo.


Status
XvMCClearSubpicture (
  Display *display,
  XvMCSubpicture *subpicture,
  short x,
  short y,
  unsigned short width,
  unsigned short height,
  unsigned int color
)

    Clear the area of the given subpicture to "color".

    display - The connection to the server.

    subpicture - The subpicture to clear.

    x -
    y -
    width -
    height -  The rectangle in the subpicture to be cleared.

    color -  The data to fill the rectangle with. 

    Errors:

       XvMCBadSubpicture - The subpicture is invalid.

Status
XvMCCompositeSubpicture (
   Display *display,
   XvMCSubpicture *subpicture,
   XvImage *image,
   short srcx,
   short srcy,
   unsigned short width,
   unsigned short height,
   short dstx,
   short dsty
)

    Copies the XvImage to the XvMCSubpicture.  

    display -  The connection to the server.

    subpicture -  The subpicture used as the destination of the copy. 

    image -  The XvImage to be used as the source of the copy. 
             XvImages should be of the shared memory variety for 
             indirect contexts.

    srcx -
    srcy -
    width -
    height -  The rectangle from the image to be composited.

    dstx -
    dsty -  The location in the subpicture where the source rectangle
            should be composited. 

    Errors:

       XvMCBadSubpicture - The subpicture is invalid.

       BadMatch -  The subpicture does not support the type of XvImage
                   passed to this function.

Status
XvMCDestroySubpicture (Display *display, XvMCSubpicture *subpicture)

   Destroys the specified subpicture.

   display - Specifies the connection to the X-server.

   subpicture - The subpicture to be destroyed.

   Errors:
   
      XvMCBadSubpicture -  The subpicture specified does not exist.


Status
XvMCSetSubpicturePalette (
  Display *display, 
  XvMCSubpicture *subpicture, 
  unsigned char *palette
)

   Set the subpicture's palette.  This applies to paletted subpictures
   only. 

    display -  The connection to the server.

    subpicture - The subpicture on which to change the palette.

    palette -  A pointer to an array holding the palette data.  The
               size of this array is 

                   num_palette_entries * entry_bytes

               in size.  The order of the components in the palette
	       is described by the component_order in the XvMCSubpicture
               structure. 

    Errors:

      XvMCBadSubpicture -  The subpicture specified does not exist.
  
      BadMatch -  The specified subpicture does not use palettes.


Status
XvMCBlendSubpicture (
   Display *display,
   XvMCSurface *target_surface,
   XvMCSubpicture *subpicture,
   short subx,
   short suby,
   unsigned short subw,
   unsigned short subh,
   short surfx,
   short surfy,
   unsigned short surfw,
   unsigned short surfh
)

Status
XvMCBlendSubpicture2 (
   Display *display,
   XvMCSurface *source_surface,
   XvMCSurface *target_surface,
   XvMCSubpicture *subpicture,
   short subx,
   short suby,
   unsigned short subw,
   unsigned short subh,
   short surfx,
   short surfy,
   unsigned short surfw,
   unsigned short surfh
)

   The behavior of these two functions is different depending on whether
or not the XVMC_BACKEND_SUBPICTURE flag is set in the XvMCSurfaceInfo.

 XVMC_BACKEND_SUBPICTURE set:

    XvMCBlendSubpicture associates the subpicture with the target_surface.
  Both will be displayed at the next call to XvMCPutSurface.  Additional
  blends before the call to XvMCPutSurface simply overrides the association.
  Both the target_surface and subpicture will query XVMC_DISPLAYING from
  the call to XvMCPutSurface until they are no longer displaying.  It is
  safe to associate the subpicture and target_surface before rendering has
  completed (while they still query XVMC_RENDERING) but it is not safe to
  call XvMCPutSurface at that time. 

    XvMCBlendSubpicture2 copies the source_surface to the target_surface
  and associates the subpicture with the target_surface.  This essentially
  calls XvMCBlendSubpicture on the target_surface after the copy.  Both
  the subpicture and target_surface will query XVMC_DISPLAYING from the
  call to XvMCPutSurface until they are no longer displaying.  The
  source_surface will not query XVMC_DISPLAYING as a result of this function.
  The copy is pipelined with the rendering and will cause XVMC_RENDERING
  to be queried until the copy is done.


 XVMC_BACKEND_SUBPICTURE not set ("frontend" behavior):

    XvMCBlendSubpicture is a no-op in this case.

    XvMCBlendSubpicture2 blends the source_surface and subpicture and
  puts it in the target_surface.  This does not effect the status of
  the source surface but will cause the target_surface to query
  XVMC_RENDERING until the blend is completed.


  display - The connection to the server.

  subpicture - The subpicture to be blended into the video.

  target_surface - The surface to be displayed with the blended subpicture.

  source_surface - Source surface prior to blending.

  subx -
  suby -
  subw -
  subh -  The rectangle from the subpicture to be blended.

  surfx -
  surfy -
  surfw -
  surfh - The rectangle in the XvMCSurface to blend the subpicture rectangle
          into.  If XVMC_SUBPICTURE_INDEPENDENT_SCALING is not set in the
          XvMCSurfaceInfo subw must be equal to surfw and subh must be 
          equal to surfh height or else a BadValue error occurs. 

   Errors:

    XvMCBadSurface - Any of the surfaces are invalid.

    XvMCBadSubpicture - The subpicture is invalid.

    BadMatch - The subpicture or any of the surfaces do not belong to the
               same context.

    BadValue - XVMC_SUBPICTURE_INDEPENDENT_SCALING is set and the source
               and destination rectangles are different sizes.


/***********************************************************************/

     SURFACE SYNCHRONIZATION

/***********************************************************************/


#define XVMC_RENDERING		0x00000001
#define XVMC_DISPLAYING		0x00000002

Status
XvMCSyncSurface (Display *display, XvMCSurface *surface)

   This function blocks until all rendering requests on the surface
  have been completed. 

     display - The connection to the server.

     surface - The surface to synchronize.

     Errors:

         XvMCBadSurface - The surface is not valid.


Status
XvMCFlushSurface (Display *display, XvMCSurface *surface)
   
   This function commits pending rendering requests to ensure that
  they will be completed in a finite amount of time. 

    display -  The connnection to the server.

    surface -  The surface whos rendering requests should be flushed.

     Errors:

         XvMCBadSurface - The surface is not valid.


Status
XvMCGetSurfaceStatus (Display *display, XvMCSurface *surface, int *stat)

   display -  The connection to the server.
  
   surface -  The surface whos status is being queried.

   stat -  May be any of the following OR'd together:

   XVMC_RENDERING - The last XvMCRenderSurface request has not completed
                    yet.

   XVMC_DISPLAYING - The surface is currently being displayed or a
                     display is pending (ie. it is not safe to render
                     to it).

    Errors:

         XvMCBadSurface - The surface is not valid.


/***********************************************************************/

     SUBPICTURE SYNCHRONIZATION

/***********************************************************************/



Status
XvMCSyncSubpicture (Display *display, XvMCSubpicture *subpicture)
   
   This function blocks until all composite/clear requests on the supicture
  have been completed.

     display - The connection to the server.

     subpicture -  The subpicture to synchronize.

     Errors:

         XvMCBadSubpicture - The subpicture is not valid.


Status
XvMCFlushSubpicture (Display *display, XvMCSubpicture *subpicture)
   
   This function commits pending composite/clear requests to ensure that
  they will be completed in a finite amount of time.  

    display - The connection to the server.

    subpicture - The subpicture whos compositing should be flushed.

     Errors:

         XvMCBadSubpicture - The surface is not valid.


Status
XvMCGetSubpictureStatus (Display *display, XvMCSubpicture *subpic, int *stat)

    display - The connection to the server.

    subpic - The subpicture whos status is being queried. 

    stat - may be any of the following OR'd together:

   XVMC_RENDERING - The last XvMCCompositeSubpicture or XvMCClearSubpicture 
                    request has not completed yet.

   XVMC_DISPLAYING - The subpicture is currently being displayed or a
                     display is pending (ie. it is not safe to render
                     to it).

     Errors:

         XvMCBadSubpicture - The surface is not valid.

/********************************************************************/

     ATTRIBUTES

/********************************************************************/

   Context specific attribute functions are provided.  These are
similar to their Xv Counterparts XvQueryPortAttributes, XvSetPortAttribute 
and XvGetPortAttribute but their state is specific to the context.

XvAttribute *
XvMCQueryAttributes (
    Display *display,
    XvMCContext *context,
    int *number
)

    An array of XvAttributes of size "number" is returned by this function.
  If there are no attributes, NULL is returned and number is set to 0.
  The array may be freed with XFree().

    display - The connection to the server.

    context - The context whos attributes we are querying.

    number - The returned number of recognized atoms.

    Errors:

	XvMCBadContext - The context is invalid.

Status
XvMCSetAttribute (
    Display *display,
    XvMCContext *context, 
    Atom attribute, 
    int value
)

    This function sets a context-specific attribute and returns Success
  if no error has occurred.

    display - The connection to the server.

    context - The context for which the attribute change is to go into effect.

    attribute - The X Atom of the attribute to be changed.

    value -  The new value of the attribute.

    Errors:

	XvMCBadContext - The context is not valid.

	BadValue - An invalid value was specified.

	BadMatch - This attribute is not defined for this context.

Status
XvMCGetAttribute (
    Display *display,
    XvMCContext *context, 
    Atom attribute, 
    int *value
)

    This function queries a context-specific attribute and return
  Success and the value if no error has occurred.

    display - The connection to the server.

    context - The context whos attribute we are querying. 

    attribute - The X Atom of the attribute to be retrieved.

    value -  The returned attribute value. 

    Errors:

        XvMCBadContext - The context is not valid.

        BadMatch - This attribute is not defined for this context.

