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Properties
| gint | brightness | Read / Write |
| gint | contrast | Read / Write |
| gint | hue | Read / Write |
| gchar * | pixel-aspect-ratio | Read / Write |
| gint | saturation | Read / Write |
| gpointer | surface | Write |
| gboolean | vsync | Read / Write |
| GstDfbVideoSinkLayerMode | layer-mode | Read / Write |
Object Hierarchy
GObject ╰── GInitiallyUnowned ╰── GstObject ╰── GstElement ╰── GstBaseSink ╰── GstVideoSink ╰── GstDfbVideoSink
Description
DfbVideoSink renders video frames using the
DirectFB library.Rendering can happen in two different modes :
-
Standalone: this mode will take complete control of the monitor forcing
DirectFB to fullscreen layout.This is convenient to test using the gst-launch-1.0 command line tool or other simple applications. It is possible to interrupt playback while being in this mode by pressing the Escape key. This mode handles navigation events for every input device supported by the DirectFB library, it will look for available video modes in the fb.modes file and try to switch the framebuffer video mode to the most suitable one. Depending on hardware acceleration capabilities the element will handle scaling or not. If no acceleration is available it will do clipping or centering of the video frames respecting the original aspect ratio.
-
Embedded: this mode will render video frames in a “surface” provided by the application developer. This is a more advanced usage of the element and it is required to integrate video playback in existing
DirectFB applications.When using this mode the element just renders to the “surface” provided by the application, that means it won't handle navigation events and won't resize the “surface” to fit video frames geometry. Application has to implement the necessary code to grab informations about the negotiated geometry and resize there “surface” accordingly.
For both modes the element implements a buffer pool allocation system to optimize memory allocation time and handle reverse negotiation. Indeed if you insert an element like videoscale in the pipeline the video sink will negotiate with it to try get a scaled video for either the fullscreen layout or the application provided external “surface”.
Example application
#include <directfb.h>
#ifdef __no_instrument_function__
#undef __no_instrument_function__
#endif
#include <stdio.h>
#include <gst/gst.h>
static IDirectFB *dfb = NULL;
static IDirectFBSurface *primary = NULL;
static GMainLoop *loop;
#define DFBCHECK(x...) \
{ \
DFBResult err = x; \
\
if (err != DFB_OK) \
{ \
fprintf( stderr, "%s <%d>:\n\t", __FILE__, __LINE__ ); \
DirectFBErrorFatal( #x, err ); \
} \
}
static gboolean
get_me_out (gpointer data)
{
g_main_loop_quit (loop);
return FALSE;
}
int
main (int argc, char *argv[])
{
DFBSurfaceDescription dsc;
GstElement *pipeline, *src, *sink;
/* Init both GStreamer and DirectFB */
DFBCHECK (DirectFBInit (&argc, &argv));
gst_init (&argc, &argv);
/* Creates DirectFB main context and set it to fullscreen layout */
DFBCHECK (DirectFBCreate (&dfb));
DFBCHECK (dfb->SetCooperativeLevel (dfb, DFSCL_FULLSCREEN));
/* We want a double buffered primary surface */
dsc.flags = DSDESC_CAPS;
dsc.caps = DSCAPS_PRIMARY | DSCAPS_FLIPPING;
DFBCHECK (dfb->CreateSurface (dfb, &dsc, &primary));
/* Creating our pipeline : videotestsrc ! dfbvideosink */
pipeline = gst_pipeline_new (NULL);
g_assert (pipeline);
src = gst_element_factory_make ("videotestsrc", NULL);
g_assert (src);
sink = gst_element_factory_make ("dfbvideosink", NULL);
g_assert (sink);
/* That's the interesting part, giving the primary surface to dfbvideosink */
g_object_set (sink, "surface", primary, NULL);
/* Adding elements to the pipeline */
gst_bin_add_many (GST_BIN (pipeline), src, sink, NULL);
if (!gst_element_link (src, sink))
g_error ("Couldn't link videotestsrc and dfbvideosink");
/* Let's play ! */
gst_element_set_state (pipeline, GST_STATE_PLAYING);
/* we need to run a GLib main loop to get out of here */
loop = g_main_loop_new (NULL, FALSE);
/* Get us out after 20 seconds */
g_timeout_add (20000, get_me_out, NULL);
g_main_loop_run (loop);
/* Release elements and stop playback */
gst_element_set_state (pipeline, GST_STATE_NULL);
/* Free the main loop */
g_main_loop_unref (loop);
/* Release DirectFB context and surface */
primary->Release (primary);
dfb->Release (dfb);
return 0;
}
Example pipelines
1 |
gst-launch-1.0 -v videotestsrc ! dfbvideosink hue=20000 saturation=40000 brightness=25000 |
test the colorbalance interface implementation in dfbvideosink
Synopsis
Property Details
The “brightness” property
“brightness” gint
The brightness of the video.
Flags: Read / Write
Allowed values: [0,65535]
Default value: 32768
The “contrast” property
“contrast” gint
The contrast of the video.
Flags: Read / Write
Allowed values: [0,65535]
Default value: 32768
The “hue” property
“hue” gint
The hue of the video.
Flags: Read / Write
Allowed values: [0,65535]
Default value: 32768
The “pixel-aspect-ratio” property
“pixel-aspect-ratio” gchar *
The pixel aspect ratio of the device.
Flags: Read / Write
Default value: "1/1"
The “saturation” property
“saturation” gint
The saturation of the video.
Flags: Read / Write
Allowed values: [0,65535]
Default value: 32768
The “vsync” property
“vsync” gboolean
Wait for next vertical sync to draw frames.
Flags: Read / Write
Default value: TRUE