dvbsubenc: Add DVB Subtitle encoder

Add an element that converts AYUV video frames to a DVB
subpicture stream.

It's fairly simple for now. Later it would be good to support
input via a stream that contains only GstVideoOverlayComposition
meta.

The element searches each input video frame for the largest
sub-region containing non-transparent pixels and encodes that
as a single DVB subpicture region. It can also do palette
reduction of the input frames using code taken from
libimagequant.

There are various FIXME for potential improvements for now, but
it works.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1227>

1 files changed, 68 insertions, 0 deletions

diff --git a/docs/plugins/gst_plugins_cache.json b/docs/plugins/gst_plugins_cache.json
index 2e46363c7..bee534490 100644
--- a/docs/plugins/gst_plugins_cache.json
+++ b/docs/plugins/gst_plugins_cache.json
@@ -12997,6 +12997,74 @@
         "tracers": {},
         "url": "Unknown package origin"
     },
+    "dvbsubenc": {
+        "description": "DVB subtitle parser and encoder",
+        "elements": {
+            "dvbsubenc": {
+                "author": "Jan Schmidt <jan@centricular.com>",
+                "description": "Encodes AYUV video frames streams into DVB subtitles",
+                "hierarchy": [
+                    "GstDvbSubEnc",
+                    "GstElement",
+                    "GstObject",
+                    "GInitiallyUnowned",
+                    "GObject"
+                ],
+                "klass": "Codec/Decoder/Video",
+                "long-name": "DVB subtitle encoder",
+                "pad-templates": {
+                    "sink": {
+                        "caps": "video/x-raw:\n         format: { AYUV }\n",
+                        "direction": "sink",
+                        "presence": "always"
+                    },
+                    "src": {
+                        "caps": "subpicture/x-dvb:\n",
+                        "direction": "src",
+                        "presence": "always"
+                    }
+                },
+                "properties": {
+                    "max-colours": {
+                        "blurb": "Maximum Number of Colours to output",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "16",
+                        "max": "256",
+                        "min": "1",
+                        "mutable": "null",
+                        "readable": true,
+                        "type": "gint",
+                        "writable": true
+                    },
+                    "ts-offset": {
+                        "blurb": "Apply an offset to incoming timestamps before output (in nanoseconds)",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "0",
+                        "max": "9223372036854775807",
+                        "min": "-9223372036854775808",
+                        "mutable": "null",
+                        "readable": true,
+                        "type": "gint64",
+                        "writable": true
+                    }
+                },
+                "rank": "none"
+            }
+        },
+        "filename": "gstdvbsubenc",
+        "license": "LGPL",
+        "other-types": {},
+        "package": "GStreamer Bad Plug-ins git",
+        "source": "gst-plugins-bad",
+        "tracers": {},
+        "url": "Unknown package origin"
+    },
     "dvbsuboverlay": {
         "description": "DVB subtitle renderer",
         "elements": {