gstvideosink

## gstvideosink gstvideosink — Base class for video sinks |

## Synopsis

    #include <gst/video/gstvideosink.h>

    struct              GstVideoSink;
    struct              GstVideoSinkClass;
    struct              GstVideoRectangle;
    #define             GST_VIDEO_SINK_HEIGHT               (obj)
    #define             GST_VIDEO_SINK_PAD                  (obj)
    #define             GST_VIDEO_SINK_WIDTH                (obj)
    void                gst_video_sink_center_rect          (GstVideoRectangle src,
                                                             GstVideoRectangle dst,
                                                             GstVideoRectangle *result,
                                                             gboolean scaling);

## Object Hierarchy

      GObject
       +----GInitiallyUnowned
             +----GstObject
                   +----GstElement
                         +----GstBaseSink
                               +----GstVideoSink

## Properties

      "show-preroll-frame"       gboolean              : Read / Write / Construct

## Description

Provides useful functions and a base class for video sinks.

GstVideoSink will configure the default base sink to drop frames that arrive later than 20ms as this is considered the default threshold for observing out-of-sync frames.

## Details

### struct GstVideoSink

    struct GstVideoSink {
      gint width, height;
    };

The video sink instance structure. Derived video sinks should set the `height` and `width` members.

gint `width`; | video width (derived class needs to set this)
gint `height`; | video height (derived class needs to set this)

### struct GstVideoSinkClass

    struct GstVideoSinkClass {
      GstBaseSinkClass parent_class;

      GstFlowReturn  (*show_frame) (GstVideoSink *video_sink, GstBuffer *buf);
    };

The video sink class structure. Derived classes should override the `show_frame` virtual function.

GstBaseSinkClass `parent_class`; | the parent class structure
`show_frame` () | render a video frame. Maps to `GstBaseSinkClass.render()` and `GstBaseSinkClass.preroll()` vfuncs. Rendering during preroll will be suppressed if the "show-preroll-frame" property is set to `FALSE`.

### struct GstVideoRectangle

    struct GstVideoRectangle {
      gint x;
      gint y;
      gint w;
      gint h;
    };

Helper structure representing a rectangular area.

gint `x`; | X coordinate of rectangle's top-left point
gint `y`; | Y coordinate of rectangle's top-left point
gint `w`; | width of the rectangle
gint `h`; | height of the rectangle

### GST_VIDEO_SINK_HEIGHT()

    #define GST_VIDEO_SINK_HEIGHT(obj) (GST_VIDEO_SINK_CAST (obj)->height)

### GST_VIDEO_SINK_PAD()

    #define GST_VIDEO_SINK_PAD(obj) GST_BASE_SINK_PAD(obj)

Get the sink GstPad of `obj`.

`obj` : | a GstVideoSink

### GST_VIDEO_SINK_WIDTH()

    #define GST_VIDEO_SINK_WIDTH(obj) (GST_VIDEO_SINK_CAST (obj)->width)

### gst_video_sink_center_rect ()

    void                gst_video_sink_center_rect          (GstVideoRectangle src,
                                                             GstVideoRectangle dst,
                                                             GstVideoRectangle *result,
                                                             gboolean scaling);

Takes `src` rectangle and position it at the center of `dst` rectangle with or without `scaling`. It handles clipping if the `src` rectangle is bigger than the `dst` one and `scaling` is set to FALSE.

`src` : | the GstVideoRectangle describing the source area
`dst` : | the GstVideoRectangle describing the destination area
`result` : | a pointer to a GstVideoRectangle which will receive the result area
`scaling` : | a gboolean indicating if scaling should be applied or not

## Property Details

### The `"show-preroll-frame"` property

      "show-preroll-frame"       gboolean              : Read / Write / Construct

Whether to show video frames during preroll. If set to FALSE, video frames will only be rendered in PLAYING state.

Default value: TRUE