textoverlay

textoverlay — Adds text strings on top of a video buffer

Synopsis

struct              GstTextOverlay;
enum                GstTextOverlayVAlign;
enum                GstTextOverlayHAlign;
enum                GstTextOverlayWrapMode;

Object Hierarchy

  GObject
   +----GstObject
         +----GstElement
               +----GstTextOverlay
                     +----GstTimeOverlay
                     +----GstClockOverlay

Properties

  "deltax"                   gint                  : Read / Write
  "deltay"                   gint                  : Read / Write
  "font-desc"                gchar*                : Write
  "halign"                   gchar*                : Write
  "shaded-background"        gboolean              : Read / Write
  "text"                     gchar*                : Read / Write
  "valign"                   gchar*                : Write
  "wrap-mode"                GstTextOverlayWrapMode  : Read / Write
  "xpad"                     gint                  : Read / Write
  "ypad"                     gint                  : Read / Write
  "halignment"               GstTextOverlayHAlign  : Read / Write
  "valignment"               GstTextOverlayVAlign  : Read / Write
  "line-alignment"           GstTextOverlayLineAlign  : Read / Write
  "silent"                   gboolean              : Read / Write
  "wait-text"                gboolean              : Read / Write
  "auto-resize"              gboolean              : Read / Write
  "vertical-render"          gboolean              : Read / Write
  "color"                    guint                 : Read / Write
  "xpos"                     gdouble               : Read / Write
  "ypos"                     gdouble               : Read / Write

Description

This plugin renders text on top of a video stream. This can be either static text or text from buffers received on the text sink pad, e.g. as produced by the subparse element. If the text sink pad is not linked, the text set via the "text" property will be rendered. If the text sink pad is linked, text will be rendered as it is received on that pad, honouring and matching the buffer timestamps of both input streams.

The text can contain newline characters and text wrapping is enabled by default.

Example launch lines

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gst-launch -v videotestsrc ! textoverlay text="Room A" valign=top halign=left ! xvimagesink
Here is a simple pipeline that displays a static text in the top left corner of the video picture
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gst-launch -v filesrc location=subtitles.srt ! subparse ! txt.   videotestsrc ! timeoverlay ! textoverlay name=txt shaded-background=yes ! xvimagesink
Here is another pipeline that displays subtitles from an .srt subtitle file, centered at the bottom of the picture and with a rectangular shading around the text in the background:

If you do not have such a subtitle file, create one looking like this in a text editor:

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00:00:03,000 --> 00:00:05,000
Hello? (3-5s)

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00:00:08,000 --> 00:00:13,000
Yes, this is a subtitle. Don't
you like it? (8-13s)

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00:00:18,826 --> 00:01:02,886
Uh? What are you talking about?
I don't understand  (18-62s)

Synopsis

Element Information

plugin

pango

author

David Schleef <ds@schleef.org>, Zeeshan Ali <zeeshan.ali@nokia.com>

class

Filter/Editor/Video

Element Pads

name

text_sink

direction

sink

presence

always

details

text/x-pango-markup

text/plain

name

video_sink

direction

sink

presence

always

details

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)65280, green_mask=(int)16711680, blue_mask=(int)-16777216, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)-16777216, green_mask=(int)16711680, blue_mask=(int)65280, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)16711680, green_mask=(int)65280, blue_mask=(int)255, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)255, green_mask=(int)65280, blue_mask=(int)16711680, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)-16777216, green_mask=(int)16711680, blue_mask=(int)65280, alpha_mask=(int)255, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)65280, green_mask=(int)16711680, blue_mask=(int)-16777216, alpha_mask=(int)255, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)16711680, green_mask=(int)65280, blue_mask=(int)255, alpha_mask=(int)-16777216, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)255, green_mask=(int)65280, blue_mask=(int)16711680, alpha_mask=(int)-16777216, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-yuv, format=(fourcc){ AYUV, I420, UYVY, NV12, NV21 }, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

name

src

direction

source

presence

always

details

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)65280, green_mask=(int)16711680, blue_mask=(int)-16777216, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)-16777216, green_mask=(int)16711680, blue_mask=(int)65280, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)16711680, green_mask=(int)65280, blue_mask=(int)255, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)24, endianness=(int)4321, red_mask=(int)255, green_mask=(int)65280, blue_mask=(int)16711680, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)-16777216, green_mask=(int)16711680, blue_mask=(int)65280, alpha_mask=(int)255, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)65280, green_mask=(int)16711680, blue_mask=(int)-16777216, alpha_mask=(int)255, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)16711680, green_mask=(int)65280, blue_mask=(int)255, alpha_mask=(int)-16777216, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianness=(int)4321, red_mask=(int)255, green_mask=(int)65280, blue_mask=(int)16711680, alpha_mask=(int)-16777216, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

video/x-raw-yuv, format=(fourcc){ AYUV, I420, UYVY, NV12, NV21 }, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

Details

struct GstTextOverlay

struct GstTextOverlay;

Opaque textoverlay object structure


enum GstTextOverlayVAlign

typedef enum {
    GST_TEXT_OVERLAY_VALIGN_BASELINE,
    GST_TEXT_OVERLAY_VALIGN_BOTTOM,
    GST_TEXT_OVERLAY_VALIGN_TOP,
    GST_TEXT_OVERLAY_VALIGN_POS,
    GST_TEXT_OVERLAY_VALIGN_CENTER
} GstTextOverlayVAlign;

Vertical alignment of the text.

GST_TEXT_OVERLAY_VALIGN_BASELINE

draw text on the baseline

GST_TEXT_OVERLAY_VALIGN_BOTTOM

draw text on the bottom

GST_TEXT_OVERLAY_VALIGN_TOP

draw text on top

GST_TEXT_OVERLAY_VALIGN_POS

draw text according to the "ypos" property

GST_TEXT_OVERLAY_VALIGN_CENTER

draw text vertically centered

enum GstTextOverlayHAlign

typedef enum {
    GST_TEXT_OVERLAY_HALIGN_LEFT,
    GST_TEXT_OVERLAY_HALIGN_CENTER,
    GST_TEXT_OVERLAY_HALIGN_RIGHT,
    GST_TEXT_OVERLAY_HALIGN_UNUSED,
    GST_TEXT_OVERLAY_HALIGN_POS
} GstTextOverlayHAlign;

Horizontal alignment of the text.

GST_TEXT_OVERLAY_HALIGN_LEFT

align text left

GST_TEXT_OVERLAY_HALIGN_CENTER

align text center

GST_TEXT_OVERLAY_HALIGN_RIGHT

align text right

GST_TEXT_OVERLAY_HALIGN_UNUSED

GST_TEXT_OVERLAY_HALIGN_POS

position text according to the "xpos" property

enum GstTextOverlayWrapMode

typedef enum {
    GST_TEXT_OVERLAY_WRAP_MODE_NONE = -1,
    GST_TEXT_OVERLAY_WRAP_MODE_WORD = PANGO_WRAP_WORD,
    GST_TEXT_OVERLAY_WRAP_MODE_CHAR = PANGO_WRAP_CHAR,
    GST_TEXT_OVERLAY_WRAP_MODE_WORD_CHAR = PANGO_WRAP_WORD_CHAR
} GstTextOverlayWrapMode;

Whether to wrap the text and if so how.

GST_TEXT_OVERLAY_WRAP_MODE_NONE

no wrapping

GST_TEXT_OVERLAY_WRAP_MODE_WORD

do word wrapping

GST_TEXT_OVERLAY_WRAP_MODE_CHAR

do char wrapping

GST_TEXT_OVERLAY_WRAP_MODE_WORD_CHAR

do word and char wrapping

Property Details

The "deltax" property

  "deltax"                   gint                  : Read / Write

Shift X position to the left or to the right. Unit is pixels.

Default value: 0


The "deltay" property

  "deltay"                   gint                  : Read / Write

Shift Y position up or down. Unit is pixels.

Default value: 0


The "font-desc" property

  "font-desc"                gchar*                : Write

Pango font description of font to be used for rendering. See documentation of pango_font_description_from_string for syntax.

Default value: ""


The "halign" property

  "halign"                   gchar*                : Write

Horizontal alignment of the text (deprecated; use halignment).

Default value: "center"


The "shaded-background" property

  "shaded-background"        gboolean              : Read / Write

Whether to shade the background under the text area.

Default value: FALSE


The "text" property

  "text"                     gchar*                : Read / Write

Text to be display.

Default value: ""


The "valign" property

  "valign"                   gchar*                : Write

Vertical alignment of the text (deprecated; use valignment).

Default value: "baseline"


The "wrap-mode" property

  "wrap-mode"                GstTextOverlayWrapMode  : Read / Write

Whether to wrap the text and if so how.

Default value: wordchar


The "xpad" property

  "xpad"                     gint                  : Read / Write

Horizontal paddding when using left/right alignment.

Allowed values: >= 0

Default value: 25


The "ypad" property

  "ypad"                     gint                  : Read / Write

Vertical padding when using top/bottom alignment.

Allowed values: >= 0

Default value: 25


The "halignment" property

  "halignment"               GstTextOverlayHAlign  : Read / Write

Horizontal alignment of the text.

Default value: center


The "valignment" property

  "valignment"               GstTextOverlayVAlign  : Read / Write

Vertical alignment of the text.

Default value: baseline


The "line-alignment" property

  "line-alignment"           GstTextOverlayLineAlign  : Read / Write

Alignment of text lines relative to each other (for multi-line text)

Default value: center

Since 0.10.15


The "silent" property

  "silent"                   gboolean              : Read / Write

If set, no text is rendered. Useful to switch off text rendering temporarily without removing the textoverlay element from the pipeline.

Default value: FALSE

Since 0.10.15


The "wait-text" property

  "wait-text"                gboolean              : Read / Write

If set, the video will block until a subtitle is received on the text pad. If video and subtitles are sent in sync, like from the same demuxer, this property should be set.

Default value: TRUE

Since 0.10.20


The "auto-resize" property

  "auto-resize"              gboolean              : Read / Write

Automatically adjust font size to screen-size.

Default value: TRUE


The "vertical-render" property

  "vertical-render"          gboolean              : Read / Write

Vertical Render.

Default value: FALSE


The "color" property

  "color"                    guint                 : Read / Write

Color of the rendered text.

Default value: 4294967295

Since 0.10.31


The "xpos" property

  "xpos"                     gdouble               : Read / Write

Horizontal position of the rendered text when using positioned alignment.

Allowed values: [0,1]

Default value: 0.5

Since 0.10.31


The "ypos" property

  "ypos"                     gdouble               : Read / Write

Vertical position of the rendered text when using positioned alignment.

Allowed values: [0,1]

Default value: 0.5

Since 0.10.31

See Also

GstTextRender, GstClockOverlay, GstTimeOverlay, GstSubParse