videobox

This plugin crops or enlarges the image. It takes 4 values as input, a top, bottom, left and right offset. Positive values will crop that much pixels from the respective border of the image, negative values will add that much pixels. When pixels are added, you can specify their color. Some predefined colors are usable with an enum property.

The plugin is alpha channel aware and will try to negotiate with a format that supports alpha channels first. When alpha channel is active two other properties, alpha and border_alpha can be used to set the alpha values of the inner picture and the border respectively. an alpha value of 0.0 means total transparency, 1.0 is opaque.

The videobox plugin has many uses such as doing a mosaic of pictures, letterboxing video, cutting out pieces of video, picture in picture, etc..

Setting autocrop to true changes the behavior of the plugin so that caps determine crop properties rather than the other way around: given input and output dimensions, the crop values are selected so that the smaller frame is effectively centered in the larger frame. This involves either cropping or padding.

If you use autocrop there is little point in setting the other properties manually because they will be overridden if the caps change, but nothing stops you from doing so.

Sample pipeline:

 gst-launch-1.0 videotestsrc ! videobox autocrop=true ! \
   "video/x-raw, width=600, height=400" ! videoconvert ! ximagesink

Hierarchy

GObject
    ╰──GInitiallyUnowned
        ╰──GstObject
            ╰──GstElement
                ╰──GstBaseTransform
                    ╰──GstVideoFilter
                        ╰──videobox

Factory details

Authors: – Wim Taymans

Classification:Filter/Effect/Video

Rank – none

Plugin – gstvideobox

Package – GStreamer Good Plug-ins git

Pad Templates

sink

video/x-raw:
         format: { AYUV, ARGB, BGRA, ABGR, RGBA, xRGB, BGRx, xBGR, RGBx, RGB, BGR, Y444, Y42B, YUY2, YVYU, UYVY, I420, YV12, Y41B, GRAY8, GRAY16_BE, GRAY16_LE }
          width: [ 1, 2147483647 ]
         height: [ 1, 2147483647 ]
      framerate: [ 0/1, 2147483647/1 ]

Presencealways

Directionsink


src

video/x-raw:
         format: { AYUV, ARGB, BGRA, ABGR, RGBA, xRGB, BGRx, xBGR, RGBx, RGB, BGR, Y444, Y42B, YUY2, YVYU, UYVY, I420, YV12, Y41B, GRAY8, GRAY16_BE, GRAY16_LE }
          width: [ 1, 2147483647 ]
         height: [ 1, 2147483647 ]
      framerate: [ 0/1, 2147483647/1 ]

Presencealways

Directionsrc


Properties

alpha

“alpha” gdouble *

Alpha value picture

Flags : Read / Write

Default value : 1


autocrop

“autocrop” gboolean *

If set to TRUE videobox will automatically crop/pad the input video to be centered in the output.

Flags : Read / Write

Default value : false


border-alpha

“border-alpha” gdouble *

Alpha value of the border

Flags : Read / Write

Default value : 1


bottom

“bottom” gint *

Pixels to box at bottom (<0 = add a border)

Flags : Read / Write

Default value : 0


fill

“fill” Video-box-fill

How to fill the borders

Flags : Read / Write

Default value : black (0)


left

“left” gint *

Pixels to box at left (<0 = add a border)

Flags : Read / Write

Default value : 0


name

“name” gchararray *

The name of the object

Flags : Read / Write / Construct

Default value : NULL


parent

“parent” GstObject *

The parent of the object

Flags : Read / Write


qos

“qos” gboolean *

Handle Quality-of-Service events

Flags : Read / Write

Default value : true


right

“right” gint *

Pixels to box at right (<0 = add a border)

Flags : Read / Write

Default value : 0


top

“top” gint *

Pixels to box at top (<0 = add a border)

Flags : Read / Write

Default value : 0


Named constants

Video-box-fill

Members

black (0) – Black
green (1) – Green
blue (2) – Blue
red (3) – Red
yellow (4) – Yellow
white (5) – White

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