Name 

    NV_video_output

Name Strings 

    GLX_NV_video_out

Contact 

    Thomas True, Nvidia, ttrue@nvidia.com
    Ian Williams, Nvidia, iwilliams@nvidia.com
    Martin Schwarzer, Nvidia, mschwarzer@nvidia.com
    Andy Ritger, Nvidia, aritger@nvidia.com

Status 

    Shipping since 2004 for NVIDIA Quadro SDI (Serial Digital Interface)

Version 
    Last Modified:      2014/06/04
    NVIDIA Revision:    8

Number 

    348

Dependencies 

    OpenGL 1.1 is required.
    GLX 1.3 is required.

Overview 

    This extension permits a color and or depth buffer of a pbuffer to
    be used for rendering and subsequent video output.  After a pbuffer 
    has been bound to a video device, subsequent color and or depth 
    rendering into that buffer may be displayed on the video output.

    This is intended for use with NVIDIA products such as the Quadro FX
    4000 SDI.

Issues 

 1. Should the new pbuffer attributes be available through GL queries? 

    No, like other pbuffer attributes you need to query them through the 
    window system extension. This extension does not make any changes to 
    OpenGL. 

 2. Should glXSendPbufferToVideoNV require that the pbuffer be current?

Implementation Notes

 1. Any created pbuffers must be the same resolution as that specified
    by the state of the video output device.  The current state of the
    video output device can be queried via the NV-CONTROL X extension.

 2. Applications may use a single pbuffer or a collection of pbuffers
    to send frames/fields to a video device.  In the first case, an
    application should block on the call to glXSendPbufferToVideoNV() to
    ensure synchronization.  In the second case, an application should
    utilize glXGetVideoInfoNV() in order to query vblank and
    buffer counters for synchronization.

Intended Usage 

    1) Configure the video output device via the NV-CONTROL X extension.

    2) Use glXGetFBConfigs or glXChooseFBConfig to find a suitable
       FBConfig for rendering images.  GLX_DRAWABLE_TYPE must have
       GLX_PBUFFER_BIT set.  The per-component pixel depth of the pbuffer
       must be equal to or greater than the per-component depth of the
       video output.

    3) Create a GLXPbuffer for each stream of video by calling
       glXCreatePbuffer.  Set the width and height for each GLXPbuffer
       to match that of the intended video output device.

    4) Call glXGetVideoDeviceNV to retrieve the handles for all 
       video devices available.  A video device handle is required
       for each video stream.  glXGetVideoDeviceNV will lock the
       video device for exclusive use by this GLX client.  The NV-CONTROL
       X extension will not be able to update video out attributes until
       the video device is released with glXReleaseVideoDeviceNV.

    5) Call glXBindVideoImageNV to bind each GLXPbuffer to a
       corresponding video device handle.  Multiple pbuffers can
       be bound, at the same time, to the same video device.

    6) Render the current frame/field for each stream to one of the bound
       GLXPbuffers. Once rendering is complete, call
       glXSendPbufferToVideoNV to send each frame/field to the video
       device.

    7) Render subsequent video frames or fields calling
       glXSendPbufferToVideoNV() at the completion of rendering for
       each frame/field.

    8) Call glXReleaseVideoImageNV to unbind each GLXPbuffer
       from its associated video device.

    9) Call glXReleaseVideoDeviceNV to release the video device.

New Types
    
    /*
     * GLXVideoDeviceNV is an opaque handle to a video device.
     */
    typedef unsigned int GLXVideoDeviceNV;


New Procedures and Functions 

    int glXGetVideoDeviceNV(Display *dpy, int screen, int numVideoDevices,
                            GLXVideoDeviceNV *pVideoDevice);

    int glXReleaseVideoDeviceNV(Display *dpy, int screen,
                                GLXVideoDeviceNV VideoDevice);

    int glXBindVideoImageNV(Display *dpy, GLXVideoDeviceNV VideoDevice,
                            GLXPbuffer pbuf, int iVideoBuffer);

    int glXReleaseVideoImageNV(Display *dpy, GLXPbuffer pbuf);

    int glXSendPbufferToVideoNV(Display *dpy, GLXPbuffer pbuf,
                                int iBufferType,
                                unsigned long *pulCounterPbuffer,
                                GLboolean bBlock);

    int glXGetVideoInfoNV(Display *dpy, int screen,
                          GLXVideoDeviceNV VideoDevice,
                          unsigned long *pulCounterOutputPbuffer,
                          unsigned long *pulCounterOutputVideo);

New Tokens 

    Accepted by the <iVideoBuffer> parameter of glXBindVideoImageNV:

        GLX_VIDEO_OUT_COLOR_NV                          0x20C3
        GLX_VIDEO_OUT_ALPHA_NV                          0x20C4
        GLX_VIDEO_OUT_DEPTH_NV                          0x20C5
        GLX_VIDEO_OUT_COLOR_AND_ALPHA_NV                0x20C6
        GLX_VIDEO_OUT_COLOR_AND_DEPTH_NV                0x20C7

    Accepted by the <iBufferType> parameter of glXSendPbufferToVideoNV:

        GLX_VIDEO_OUT_FRAME_NV                          0x20C8
        GLX_VIDEO_OUT_FIELD_1_NV                        0x20C9
        GLX_VIDEO_OUT_FIELD_2_NV                        0x20CA
        GLX_VIDEO_OUT_STACKED_FIELDS_1_2_NV             0x20CB
        GLX_VIDEO_OUT_STACKED_FIELDS_2_1_NV             0x20CC

Additions to Chapter 2 of the OpenGL 1.2.1 Specification (OpenGL Operation) 

    None. 

Additions to Chapter 3 of the OpenGL 1.2.1 Specification (Rasterization) 

    None. 

Additions to Chapter 4 of the OpenGL 1.2.1 Specification (Per-Fragment 
Operations and the Frame Buffer) 

    None. 

Additions to Chapter 5 of the OpenGL 1.2.1 Specification (Special Functions) 

    None. 

Additions to Chapter 6 of the OpenGL 1.2.1 Specification (State and State 
Requests) 

    None. 


Additions to the GLX 1.3 Specification

    [Add new section, Video Out]

    Video out functions permit color and depth buffers from a
    pbuffer to be sent to a video output device.
    
    The command

        int glXGetVideoDeviceNV(Display *dpy, int screen, int numVideoDevices,
                                GLXVideoDeviceNV *pVideoDevice);

    fills in the array <pVideoDevice> with up to <numVideoDevices>
    handles to the available video devices.  <numVideoDevices> must be
    non-negative, and <pVideoDevice> must not be NULL.

    It is not an error if the number of available video devices is larger
    that <numVideoDevices>; in that case the first <numVideoDevices>
    device handles are returned.  It is an error if <numVideoDevices>
    is larger than the number of available video devices.  The order of
    devices returned in <pVideoDevice> is implementation dependent.

    If glXGetVideoDeviceNV succeeds, 0 is returned.  Otherwise, a non-zero
    error code is returned.


    The command

        int glXReleaseVideoDeviceNV(Display *dpy, int screen,
                                    GLXVideoDeviceNV VideoDevice);

    releases all resources associated with <VideoDevice>.

    If glXReleaseVideoDeviceNV succeeds, 0 is returned.  Otherwise,
    a non-zero error code is returned.


    The command

        int glXBindVideoImageNV(Display *dpy, GLXVideoDeviceNV VideoDevice,
                                GLXPbuffer pbuf, int iVideoBuffer);

    binds <pbuf> to <VideoDevice> for subsequent scanout where
    <iVideoBuffer> specifies that <pbuf> contains color, alpha and/or
    depth data.  Valid values for <iVideoBuffer> are:

        GLX_VIDEO_OUT_COLOR_NV                          0x20C3
        GLX_VIDEO_OUT_ALPHA_NV                          0x20C4
        GLX_VIDEO_OUT_DEPTH_NV                          0x20C5
        GLX_VIDEO_OUT_COLOR_AND_ALPHA_NV                0x20C6
        GLX_VIDEO_OUT_COLOR_AND_DEPTH_NV                0x20C7

    <pbuf> cannot be None, and <VideoDevice> must be a VideoDevice
    returned by glXGetVideoDeviceNV().


    A pbuffer can only be bound to one GLXVideoDeviceNV at a time.
    If <pbuf> is already bound to a different GLXVideoDeviceNV, then
    glXBindVideoImageNV will fail.


    If glXBindVideoImageNV succeeds, 0 is returned.  Otherwise, 
    a non-zero error code is returned.


    The command

        int glXReleaseVideoImageNV(Display *dpy, GLXPbuffer pbuf);

    releases <pbuf> from a previously bound video device.  <pbuf> may
    not be None.

    If glXReleaseVideoImageNV succeeds, 0 is returned.  Otherwise,
    a non-zero error code is returned.


    The command

        int glXSendPbufferToVideoNV(Display *dpy, GLXPbuffer pbuf,
                                    int iBufferType,
                                    unsigned long *pulCounterPbuffer,
                                    Bool bBlock);

    indicates that rendering to the <pbuf> is complete and that the
    completed frame/field contained with <pbuf> is ready for scan out by
    the video device where <iBufferType> specifies that <pbuf> contains
    the first field, second field or a complete frame.  Valid values
    for <iBufferType> are:

        GLX_VIDEO_OUT_FRAME_NV                          0x20C8
        GLX_VIDEO_OUT_FIELD_1_NV                        0x20C9
        GLX_VIDEO_OUT_FIELD_2_NV                        0x20CA

    The color buffer controlled by glReadBuffer is used as the color
    buffer input to glXSendPbufferToVideoNV().  <pbuf> cannot be None.
    The <bBlock> argument specifies whether or not the call should
    block until scan out of the specified frame/field is complete.
    <pulCounterPbuffer> returns the total number of frames/fields sent
    to the video device.

    If glXSendPbufferToVideoNV succeeds, 0 is returned.  Otherwise,
    a non-zero error code is returned.


    The command

        int glXGetVideoInfoNV(GLXVideoDeviceNV VideoDevice,
                              unsigned long *pulCounterOutputPbuffer,
                              unsigned long *pulCounterOutputVideo);

    returns in <pulCounterOutputVideo> the absolute count of vertical
    blanks on <VideoDevice> since transfers were started while
    <pulCounterOutputPbuffer> returns the count of the current pbuffer
    being scanned out by <VideoDevice>.

    If glXGetVideoInfoNV succeeds, 0 is returned.  Otherwise, a non-zero
    error code is returned.


GLX Protocol

    Six new GLX protocol commands are added.

    GetVideoDeviceNV
        1       CARD8       opcode (X assigned)
        1       17          GLX opcode (glXVendorPrivateWithReply)
        2       5           request length
        4       1313        vendor specific opcode
        4                   unused
        4       CARD32      num_devices
        4       CARD32      screen
      =>
        1       CARD8       reply
        1                   unused
        2       CARD16      sequence number
        4       n           reply length
        4       CARD32      status
        4       CARD32      num_devices
        16                  unused
        4 * n   CARD32      video_device handles

    Where n is the number of device handles returned.


    ReleaseVideoDeviceNV
        1       CARD8       opcode (X assigned)
        1       17          GLX opcode (glXVendorPrivateWithReply)
        2       5           request length
        4       1314        vendor specific opcode
        4                   unused
        4       CARD32      video_device
        4       CARD32      screen
      =>
        1       CARD8       reply
        1                   unused
        2       CARD16      sequence number 
        4       0           reply length
        4       CARD32      status
        20                  unused


    BindVideoImageNV
        1       CARD8       opcode (X assigned)
        1       17          GLX opcode (glXVendorPrivateWithReply)
        2       6           request length
        4       1315        vendor specific opcode
        4                   unused
        4       GLX_PBUFFER pbuffer
        4       CARD32      video_device
        4       CARD32      video_buffer
      =>
        1       CARD8       reply
        1                   unused
        2       CARD16      sequence number
        4       0           reply length
        4       CARD32      status
        20                  unused


    ReleaseVideoImageNV
        1       CARD8       opcode (X assigned)
        1       17          GLX opcode (glXVendorPrivateWithReply)
        2       4           request length
        4       1316        vendor specific opcode
        4       GLX_PBUFFER pbuffer
      =>
        1       CARD8       reply
        1                   unused
        2       CARD16      sequence number
        4       0           reply length
        4       CARD32      status
        20                  unused


    SendPbufferToVideoNV
        1       CARD8       opcode (X assigned)
        1       17          GLX opcode (glXVendorPrivateWithReply)
        2       6           request length
        4       1317        vendor specific opcode
        4                   unused
        4       GLX_PBUFFER pbuffer
        4       CARD32      buffer_type
        1       BOOL        block
        1                   unused
        2                   unused
      =>
        1       CARD8       reply
        1                   unused
        2       CARD16      sequence number
        4       0           reply length
        4       CARD32      status
        4       CARD32      counter_pbuffer
        16                  unused


    GetVideoInfoNV
        1       CARD8       opcode (X assigned)
        1       17          GLX opcode (glXVendorPrivateWithReply)
        2       5           request length
        4       1318        vendor specific opcode
        4       CARD32      screen
        4       CARD32      video_device
      =>
        1       CARD8       reply
        1                   unused
        2       CARD16      sequence number
        4       0           reply length
        4       CARD32      status
        4       CARD32      counter_video
        4       CARD32      counter_pbuffer
        12                  unused

New State

    None

New Implementation Dependent State

    None

History

    Revision 8, June 4, 2014 (jajones)
      - Fix extension string to match implementation.

    Revision 7, February 6, 2013 (pbrown)
      - Fix GLX protocol section to remove the duplicate
        opcode and match the implementation.

    Revision 6, February 20, 2008
      - Internal revisions.