compositor

compositor

Properties

GstCompositorBackground background Read / Write

Object Hierarchy

    GObject
    ╰── GInitiallyUnowned
        ╰── GstObject
            ├── GstElement
               ╰── GstAggregator
                   ╰── GstVideoAggregator
                       ╰── GstCompositor
            ╰── GstPad
                ╰── GstAggregatorPad
                    ╰── GstVideoAggregatorPad
                        ╰── GstCompositorPad

Description

Compositor can accept AYUV, ARGB and BGRA video streams. For each of the requested sink pads it will compare the incoming geometry and framerate to define the output parameters. Indeed output video frames will have the geometry of the biggest incoming video stream and the framerate of the fastest incoming one.

Compositor will do colorspace conversion.

Individual parameters for each input stream can be configured on the GstCompositorPad:

  • "xpos": The x-coordinate position of the top-left corner of the picture (gint)
  • "ypos": The y-coordinate position of the top-left corner of the picture (gint)
  • "width": The width of the picture; the input will be scaled if necessary (gint)
  • "height": The height of the picture; the input will be scaled if necessary (gint)
  • "alpha": The transparency of the picture; between 0.0 and 1.0. The blending is a simple copy when fully-transparent (0.0) and fully-opaque (1.0). (gdouble)
  • "zorder": The z-order position of the picture in the composition (guint)

Sample pipelines

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gst-launch-1.0 \
  videotestsrc pattern=1 ! \
  video/x-raw,format=AYUV,framerate=\(fraction\)10/1,width=100,height=100 ! \
  videobox border-alpha=0 top=-70 bottom=-70 right=-220 ! \
  compositor name=comp sink_0::alpha=0.7 sink_1::alpha=0.5 ! \
  videoconvert ! xvimagesink \
  videotestsrc ! \
  video/x-raw,format=AYUV,framerate=\(fraction\)5/1,width=320,height=240 ! comp.
A pipeline to demonstrate compositor used together with videobox. This should show a 320x240 pixels video test source with some transparency showing the background checker pattern. Another video test source with just the snow pattern of 100x100 pixels is overlayed on top of the first one on the left vertically centered with a small transparency showing the first video test source behind and the checker pattern under it. Note that the framerate of the output video is 10 frames per second.
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gst-launch-1.0 videotestsrc pattern=1 ! \
  video/x-raw, framerate=\(fraction\)10/1, width=100, height=100 ! \
  compositor name=comp ! videoconvert ! ximagesink \
  videotestsrc !  \
  video/x-raw, framerate=\(fraction\)5/1, width=320, height=240 ! comp.
A pipeline to demostrate bgra comping. (This does not demonstrate alpha blending).
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gst-launch-1.0 videotestsrc pattern=1 ! \
  video/x-raw,format =I420, framerate=\(fraction\)10/1, width=100, height=100 ! \
  compositor name=comp ! videoconvert ! ximagesink \
  videotestsrc ! \
  video/x-raw,format=I420, framerate=\(fraction\)5/1, width=320, height=240 ! comp.
A pipeline to test I420
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gst-launch-1.0 compositor name=comp sink_1::alpha=0.5 sink_1::xpos=50 sink_1::ypos=50 ! \
  videoconvert ! ximagesink \
  videotestsrc pattern=snow timestamp-offset=3000000000 ! \
  "video/x-raw,format=AYUV,width=640,height=480,framerate=(fraction)30/1" ! \
  timeoverlay ! queue2 ! comp. \
  videotestsrc pattern=smpte ! \
  "video/x-raw,format=AYUV,width=800,height=600,framerate=(fraction)10/1" ! \
  timeoverlay ! queue2 ! comp.
A pipeline to demonstrate synchronized compositing (the second stream starts after 3 seconds)

Functions

Types and Values

Property Details

The “background” property

  “background”               GstCompositorBackground

Background type.

Flags: Read / Write

Default value: Checker pattern