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compositor: expose zero-size-is-unscaled property
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When that property is left to its default, the width and height
property considers frames from input pads with width or height <= 0
should be left unscaled in that dimension.

Setting this property to FALSE changes that behaviour to < 0, as when
animating these properties, 0 should be a valid end value (eg. shrinking
an input stream until it disappears).

The default value of the width and height properties is set to -1, so that
the default behaviour stays consistent whether that new property is set
or not.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/923>
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@MathieuDuponchelle
MathieuDuponchelle authored and GStreamer Merge Bot committed Nov 13, 2020
1 parent c50f447 commit fe20cac
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Showing 3 changed files with 85 additions and 19 deletions.
16 changes: 14 additions & 2 deletions docs/plugins/gst_plugins_cache.json
View file
Expand Up @@ -1790,6 +1790,18 @@
"readable": true,
"type": "GstCompositorBackground",
"writable": true
},
"zero-size-is-unscaled": {
"blurb": "If TRUE, then input video is unscaled in that dimension if width or height is 0 (for backwards compatibility)",
"conditionally-available": false,
"construct": false,
"construct-only": false,
"controllable": false,
"default": "true",
"mutable": "null",
"readable": true,
"type": "gboolean",
"writable": true
}
},
"rank": "primary + 1"
Expand Down Expand Up @@ -1876,7 +1888,7 @@
"construct": false,
"construct-only": false,
"controllable": true,
"default": "0",
"default": "-1",
"max": "2147483647",
"min": "-2147483648",
"mutable": "null",
Expand All @@ -1902,7 +1914,7 @@
"construct": false,
"construct-only": false,
"controllable": true,
"default": "0",
"default": "-1",
"max": "2147483647",
"min": "-2147483648",
"mutable": "null",
Expand Down
80 changes: 63 additions & 17 deletions gst/compositor/compositor.c
View file
Expand Up @@ -167,8 +167,8 @@ gst_compositor_background_get_type (void)

#define DEFAULT_PAD_XPOS 0
#define DEFAULT_PAD_YPOS 0
#define DEFAULT_PAD_WIDTH 0
#define DEFAULT_PAD_HEIGHT 0
#define DEFAULT_PAD_WIDTH -1
#define DEFAULT_PAD_HEIGHT -1
#define DEFAULT_PAD_ALPHA 1.0
#define DEFAULT_PAD_OPERATOR COMPOSITOR_OPERATOR_OVER
enum
Expand Down Expand Up @@ -254,8 +254,8 @@ gst_compositor_pad_set_property (GObject * object, guint prop_id,
}

static void
_mixer_pad_get_output_size (GstCompositorPad * comp_pad, gint out_par_n,
gint out_par_d, gint * width, gint * height)
_mixer_pad_get_output_size (GstCompositor * comp, GstCompositorPad * comp_pad,
gint out_par_n, gint out_par_d, gint * width, gint * height)
{
GstVideoAggregatorPad *vagg_pad = GST_VIDEO_AGGREGATOR_PAD (comp_pad);
gint pad_width, pad_height;
Expand All @@ -270,12 +270,27 @@ _mixer_pad_get_output_size (GstCompositorPad * comp_pad, gint out_par_n,
return;
}

pad_width =
comp_pad->width <=
0 ? GST_VIDEO_INFO_WIDTH (&vagg_pad->info) : comp_pad->width;
pad_height =
comp_pad->height <=
0 ? GST_VIDEO_INFO_HEIGHT (&vagg_pad->info) : comp_pad->height;
if (comp->zero_size_is_unscaled) {
pad_width =
comp_pad->width <=
0 ? GST_VIDEO_INFO_WIDTH (&vagg_pad->info) : comp_pad->width;
pad_height =
comp_pad->height <=
0 ? GST_VIDEO_INFO_HEIGHT (&vagg_pad->info) : comp_pad->height;
} else {
pad_width =
comp_pad->width <
0 ? GST_VIDEO_INFO_WIDTH (&vagg_pad->info) : comp_pad->width;
pad_height =
comp_pad->height <
0 ? GST_VIDEO_INFO_HEIGHT (&vagg_pad->info) : comp_pad->height;
}

if (pad_width == 0 || pad_height == 0) {
*width = 0;
*height = 0;
return;
}

if (!gst_video_calculate_display_ratio (&dar_n, &dar_d, pad_width, pad_height,
GST_VIDEO_INFO_PAR_N (&vagg_pad->info),
Expand Down Expand Up @@ -357,8 +372,9 @@ _pad_obscures_rectangle (GstVideoAggregator * vagg, GstVideoAggregatorPad * pad,
pad_rect.x = cpad->xpos;
pad_rect.y = cpad->ypos;
/* Handle pixel and display aspect ratios to find the actual size */
_mixer_pad_get_output_size (cpad, GST_VIDEO_INFO_PAR_N (&vagg->info),
GST_VIDEO_INFO_PAR_D (&vagg->info), &(pad_rect.w), &(pad_rect.h));
_mixer_pad_get_output_size (GST_COMPOSITOR (vagg), cpad,
GST_VIDEO_INFO_PAR_N (&vagg->info), GST_VIDEO_INFO_PAR_D (&vagg->info),
&(pad_rect.w), &(pad_rect.h));

if (!is_rectangle_contained (rect, pad_rect))
return FALSE;
Expand Down Expand Up @@ -395,8 +411,9 @@ gst_compositor_pad_prepare_frame (GstVideoAggregatorPad * pad,
* width/height. See ->set_info()
* */

_mixer_pad_get_output_size (cpad, GST_VIDEO_INFO_PAR_N (&vagg->info),
GST_VIDEO_INFO_PAR_D (&vagg->info), &width, &height);
_mixer_pad_get_output_size (GST_COMPOSITOR (vagg), cpad,
GST_VIDEO_INFO_PAR_N (&vagg->info), GST_VIDEO_INFO_PAR_D (&vagg->info),
&width, &height);

if (cpad->alpha == 0.0) {
GST_DEBUG_OBJECT (pad, "Pad has alpha 0.0, not converting frame");
Expand Down Expand Up @@ -451,8 +468,9 @@ gst_compositor_pad_create_conversion_info (GstVideoAggregatorConvertPad * pad,
if (!conversion_info->finfo)
return;

_mixer_pad_get_output_size (cpad, GST_VIDEO_INFO_PAR_N (&vagg->info),
GST_VIDEO_INFO_PAR_D (&vagg->info), &width, &height);
_mixer_pad_get_output_size (GST_COMPOSITOR (vagg), cpad,
GST_VIDEO_INFO_PAR_N (&vagg->info), GST_VIDEO_INFO_PAR_D (&vagg->info),
&width, &height);

/* The only thing that can change here is the width
* and height, otherwise set_info would've been called */
Expand Down Expand Up @@ -532,15 +550,19 @@ gst_compositor_pad_init (GstCompositorPad * compo_pad)
compo_pad->ypos = DEFAULT_PAD_YPOS;
compo_pad->alpha = DEFAULT_PAD_ALPHA;
compo_pad->op = DEFAULT_PAD_OPERATOR;
compo_pad->width = DEFAULT_PAD_WIDTH;
compo_pad->height = DEFAULT_PAD_HEIGHT;
}


/* GstCompositor */
#define DEFAULT_BACKGROUND COMPOSITOR_BACKGROUND_CHECKER
#define DEFAULT_ZERO_SIZE_IS_UNSCALED TRUE
enum
{
PROP_0,
PROP_BACKGROUND,
PROP_ZERO_SIZE_IS_UNSCALED,
};

static void
Expand All @@ -553,6 +575,9 @@ gst_compositor_get_property (GObject * object,
case PROP_BACKGROUND:
g_value_set_enum (value, self->background);
break;
case PROP_ZERO_SIZE_IS_UNSCALED:
g_value_set_boolean (value, self->zero_size_is_unscaled);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
Expand All @@ -569,6 +594,9 @@ gst_compositor_set_property (GObject * object,
case PROP_BACKGROUND:
self->background = g_value_get_enum (value);
break;
case PROP_ZERO_SIZE_IS_UNSCALED:
self->zero_size_is_unscaled = g_value_get_boolean (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
Expand Down Expand Up @@ -786,7 +814,8 @@ _fixate_caps (GstAggregator * agg, GstCaps * caps)

fps_n = GST_VIDEO_INFO_FPS_N (&vaggpad->info);
fps_d = GST_VIDEO_INFO_FPS_D (&vaggpad->info);
_mixer_pad_get_output_size (compositor_pad, par_n, par_d, &width, &height);
_mixer_pad_get_output_size (GST_COMPOSITOR (vagg), compositor_pad, par_n,
par_d, &width, &height);

if (width == 0 || height == 0)
continue;
Expand Down Expand Up @@ -1374,6 +1403,22 @@ gst_compositor_class_init (GstCompositorClass * klass)
GST_TYPE_COMPOSITOR_BACKGROUND,
DEFAULT_BACKGROUND, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

/**
* compositor:zero-size-is-unscaled:
*
* Whether a pad with height or width 0 should be left unscaled
* in that dimension, or simply not composited in. Setting it to
* %FALSE might be useful when animating those properties.
*
* Since: 1.20
*/
g_object_class_install_property (gobject_class, PROP_ZERO_SIZE_IS_UNSCALED,
g_param_spec_boolean ("zero-size-is-unscaled", "Zero size is unscaled",
"If TRUE, then input video is unscaled in that dimension "
"if width or height is 0 (for backwards compatibility)",
DEFAULT_ZERO_SIZE_IS_UNSCALED,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

gst_element_class_add_static_pad_template_with_gtype (gstelement_class,
&src_factory, GST_TYPE_AGGREGATOR_PAD);
gst_element_class_add_static_pad_template_with_gtype (gstelement_class,
Expand All @@ -1394,6 +1439,7 @@ gst_compositor_init (GstCompositor * self)
{
/* initialize variables */
self->background = DEFAULT_BACKGROUND;
self->zero_size_is_unscaled = DEFAULT_ZERO_SIZE_IS_UNSCALED;
}

/* GstChildProxy implementation */
Expand Down
8 changes: 8 additions & 0 deletions gst/compositor/compositor.h
View file
Expand Up @@ -114,6 +114,14 @@ struct _GstCompositor
GstVideoAggregator videoaggregator;
GstCompositorBackground background;

/* Property to allow overriding the default behaviour of
* pad.width == 0 or pad.height == 0: by default it means the input
* image should be left unscaled in that dimension, but it may be desirable
* to have it simply mean the image should not be composited into the output
* image, for example when animating the property.
*/
gboolean zero_size_is_unscaled;

/* The 'blend' compositing function does not preserve the alpha value of the
* background, while 'overlay' does; i.e., COMPOSITOR_OPERATOR_ADD is the
* same as COMPOSITOR_OPERATOR_OVER when using the 'blend' BlendFunction. */
Expand Down

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