gstreamer/sys/decklink/gstdecklinkvideosrc.cpp

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/* GStreamer
* Copyright (C) 2011 David Schleef <ds@entropywave.com>
* Copyright (C) 2014 Sebastian Dröge <sebastian@centricular.com>
* Copyright (C) 2015 Florian Langlois <florian.langlois@fr.thalesgroup.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
* Boston, MA 02110-1335, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "gstdecklinkvideosrc.h"
#include <string.h>
GST_DEBUG_CATEGORY_STATIC (gst_decklink_video_src_debug);
#define GST_CAT_DEFAULT gst_decklink_video_src_debug
#define DEFAULT_MODE (GST_DECKLINK_MODE_AUTO)
#define DEFAULT_CONNECTION (GST_DECKLINK_CONNECTION_AUTO)
#define DEFAULT_BUFFER_SIZE (5)
enum
{
PROP_0,
PROP_MODE,
PROP_CONNECTION,
PROP_DEVICE_NUMBER,
PROP_BUFFER_SIZE
};
typedef struct
{
IDeckLinkVideoInputFrame *frame;
GstClockTime capture_time;
GstDecklinkModeEnum mode;
} CaptureFrame;
static void
capture_frame_free (void *data)
{
CaptureFrame *frame = (CaptureFrame *) data;
frame->frame->Release ();
g_free (frame);
}
typedef struct
{
IDeckLinkVideoInputFrame *frame;
IDeckLinkInput *input;
} VideoFrame;
static void
video_frame_free (void *data)
{
VideoFrame *frame = (VideoFrame *) data;
frame->frame->Release ();
frame->input->Release ();
g_free (frame);
}
static void gst_decklink_video_src_set_property (GObject * object,
guint property_id, const GValue * value, GParamSpec * pspec);
static void gst_decklink_video_src_get_property (GObject * object,
guint property_id, GValue * value, GParamSpec * pspec);
static void gst_decklink_video_src_finalize (GObject * object);
static GstStateChangeReturn
gst_decklink_video_src_change_state (GstElement * element,
GstStateChange transition);
static GstClock *gst_decklink_video_src_provide_clock (GstElement * element);
static gboolean gst_decklink_video_src_set_caps (GstBaseSrc * bsrc,
GstCaps * caps);
static GstCaps *gst_decklink_video_src_get_caps (GstBaseSrc * bsrc,
GstCaps * filter);
static gboolean gst_decklink_video_src_query (GstBaseSrc * bsrc,
GstQuery * query);
static gboolean gst_decklink_video_src_unlock (GstBaseSrc * bsrc);
static gboolean gst_decklink_video_src_unlock_stop (GstBaseSrc * bsrc);
static GstFlowReturn gst_decklink_video_src_create (GstPushSrc * psrc,
GstBuffer ** buffer);
static gboolean gst_decklink_video_src_open (GstDecklinkVideoSrc * self);
static gboolean gst_decklink_video_src_close (GstDecklinkVideoSrc * self);
static void gst_decklink_video_src_start_streams (GstElement * element);
#define parent_class gst_decklink_video_src_parent_class
G_DEFINE_TYPE (GstDecklinkVideoSrc, gst_decklink_video_src, GST_TYPE_PUSH_SRC);
static void
gst_decklink_video_src_class_init (GstDecklinkVideoSrcClass * klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
GstBaseSrcClass *basesrc_class = GST_BASE_SRC_CLASS (klass);
GstPushSrcClass *pushsrc_class = GST_PUSH_SRC_CLASS (klass);
GstCaps *templ_caps;
gobject_class->set_property = gst_decklink_video_src_set_property;
gobject_class->get_property = gst_decklink_video_src_get_property;
gobject_class->finalize = gst_decklink_video_src_finalize;
element_class->change_state =
GST_DEBUG_FUNCPTR (gst_decklink_video_src_change_state);
element_class->provide_clock =
GST_DEBUG_FUNCPTR (gst_decklink_video_src_provide_clock);
basesrc_class->get_caps = GST_DEBUG_FUNCPTR (gst_decklink_video_src_get_caps);
basesrc_class->set_caps = GST_DEBUG_FUNCPTR (gst_decklink_video_src_set_caps);
basesrc_class->query = GST_DEBUG_FUNCPTR (gst_decklink_video_src_query);
basesrc_class->unlock = GST_DEBUG_FUNCPTR (gst_decklink_video_src_unlock);
basesrc_class->unlock_stop =
GST_DEBUG_FUNCPTR (gst_decklink_video_src_unlock_stop);
pushsrc_class->create = GST_DEBUG_FUNCPTR (gst_decklink_video_src_create);
g_object_class_install_property (gobject_class, PROP_MODE,
g_param_spec_enum ("mode", "Playback Mode",
"Video Mode to use for playback",
GST_TYPE_DECKLINK_MODE, DEFAULT_MODE,
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT)));
g_object_class_install_property (gobject_class, PROP_CONNECTION,
g_param_spec_enum ("connection", "Connection",
"Video input connection to use",
GST_TYPE_DECKLINK_CONNECTION, DEFAULT_CONNECTION,
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT)));
g_object_class_install_property (gobject_class, PROP_DEVICE_NUMBER,
g_param_spec_int ("device-number", "Device number",
"Output device instance to use", 0, G_MAXINT, 0,
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
G_PARAM_CONSTRUCT)));
g_object_class_install_property (gobject_class, PROP_BUFFER_SIZE,
g_param_spec_uint ("buffer-size", "Buffer Size",
"Size of internal buffer in number of video frames", 1,
G_MAXINT, DEFAULT_BUFFER_SIZE,
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
templ_caps = gst_decklink_mode_get_template_caps ();
gst_element_class_add_pad_template (element_class,
gst_pad_template_new ("src", GST_PAD_SRC, GST_PAD_ALWAYS, templ_caps));
gst_caps_unref (templ_caps);
gst_element_class_set_static_metadata (element_class, "Decklink Video Source",
"Video/Src", "Decklink Source", "David Schleef <ds@entropywave.com>, "
"Sebastian Dröge <sebastian@centricular.com>");
GST_DEBUG_CATEGORY_INIT (gst_decklink_video_src_debug, "decklinkvideosrc",
0, "debug category for decklinkvideosrc element");
}
static void
gst_decklink_video_src_init (GstDecklinkVideoSrc * self)
{
self->mode = DEFAULT_MODE;
self->caps_mode = GST_DECKLINK_MODE_AUTO;
self->connection = DEFAULT_CONNECTION;
self->device_number = 0;
self->buffer_size = DEFAULT_BUFFER_SIZE;
gst_base_src_set_live (GST_BASE_SRC (self), TRUE);
gst_base_src_set_format (GST_BASE_SRC (self), GST_FORMAT_TIME);
g_mutex_init (&self->lock);
g_cond_init (&self->cond);
g_queue_init (&self->current_frames);
}
void
gst_decklink_video_src_set_property (GObject * object, guint property_id,
const GValue * value, GParamSpec * pspec)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (object);
switch (property_id) {
case PROP_MODE:
self->mode = (GstDecklinkModeEnum) g_value_get_enum (value);
break;
case PROP_CONNECTION:
self->connection = (GstDecklinkConnectionEnum) g_value_get_enum (value);
break;
case PROP_DEVICE_NUMBER:
self->device_number = g_value_get_int (value);
break;
case PROP_BUFFER_SIZE:
self->buffer_size = g_value_get_uint (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
break;
}
}
void
gst_decklink_video_src_get_property (GObject * object, guint property_id,
GValue * value, GParamSpec * pspec)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (object);
switch (property_id) {
case PROP_MODE:
g_value_set_enum (value, self->mode);
break;
case PROP_CONNECTION:
g_value_set_enum (value, self->connection);
break;
case PROP_DEVICE_NUMBER:
g_value_set_int (value, self->device_number);
break;
case PROP_BUFFER_SIZE:
g_value_set_uint (value, self->buffer_size);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
break;
}
}
void
gst_decklink_video_src_finalize (GObject * object)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (object);
g_mutex_clear (&self->lock);
g_cond_clear (&self->cond);
G_OBJECT_CLASS (parent_class)->finalize (object);
}
static gboolean
gst_decklink_video_src_set_caps (GstBaseSrc * bsrc, GstCaps * caps)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (bsrc);
GstCaps *current_caps;
const GstDecklinkMode *mode;
BMDVideoInputFlags flags;
HRESULT ret;
GST_DEBUG_OBJECT (self, "Setting caps %" GST_PTR_FORMAT, caps);
if ((current_caps = gst_pad_get_current_caps (GST_BASE_SRC_PAD (bsrc)))) {
GST_DEBUG_OBJECT (self, "Pad already has caps %" GST_PTR_FORMAT, caps);
if (!gst_caps_is_equal (caps, current_caps)) {
GST_ERROR_OBJECT (self, "New caps are not equal to old caps");
gst_caps_unref (current_caps);
return FALSE;
} else {
gst_caps_unref (current_caps);
return TRUE;
}
}
if (!gst_video_info_from_caps (&self->info, caps))
return FALSE;
if (self->input->config && self->connection != GST_DECKLINK_CONNECTION_AUTO) {
ret = self->input->config->SetInt (bmdDeckLinkConfigVideoInputConnection,
gst_decklink_get_connection (self->connection));
if (ret != S_OK) {
GST_ERROR_OBJECT (self, "Failed to set configuration (input source)");
return FALSE;
}
if (self->connection == GST_DECKLINK_CONNECTION_COMPOSITE) {
ret = self->input->config->SetInt (bmdDeckLinkConfigAnalogVideoInputFlags,
bmdAnalogVideoFlagCompositeSetup75);
if (ret != S_OK) {
GST_ERROR_OBJECT (self,
"Failed to set configuration (composite setup)");
return FALSE;
}
}
}
flags = bmdVideoInputFlagDefault;
if (self->mode == GST_DECKLINK_MODE_AUTO) {
bool autoDetection = false;
if (self->input->attributes) {
ret =
self->input->
attributes->GetFlag (BMDDeckLinkSupportsInputFormatDetection,
&autoDetection);
if (ret != S_OK) {
GST_ERROR_OBJECT (self, "Failed to get attribute (autodetection)");
return FALSE;
}
if (autoDetection)
flags |= bmdVideoInputEnableFormatDetection;
}
if (!autoDetection) {
GST_ERROR_OBJECT (self, "Failed to activate auto-detection");
return FALSE;
}
}
mode = gst_decklink_get_mode (self->mode);
g_assert (mode != NULL);
ret = self->input->input->EnableVideoInput (mode->mode,
bmdFormat8BitYUV, flags);
if (ret != S_OK) {
GST_WARNING_OBJECT (self, "Failed to enable video input");
return FALSE;
}
g_mutex_lock (&self->input->lock);
self->input->mode = mode;
self->input->video_enabled = TRUE;
if (self->input->start_streams)
self->input->start_streams (self->input->videosrc);
g_mutex_unlock (&self->input->lock);
return TRUE;
}
static GstCaps *
gst_decklink_video_src_get_caps (GstBaseSrc * bsrc, GstCaps * filter)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (bsrc);
GstCaps *mode_caps, *caps;
g_mutex_lock (&self->lock);
if (self->caps_mode != GST_DECKLINK_MODE_AUTO)
mode_caps = gst_decklink_mode_get_caps (self->caps_mode);
else
mode_caps = gst_decklink_mode_get_caps (self->mode);
g_mutex_unlock (&self->lock);
if (filter) {
caps =
gst_caps_intersect_full (filter, mode_caps, GST_CAPS_INTERSECT_FIRST);
gst_caps_unref (mode_caps);
} else {
caps = mode_caps;
}
return caps;
}
static void
gst_decklink_video_src_got_frame (GstElement * element,
IDeckLinkVideoInputFrame * frame, GstDecklinkModeEnum mode,
GstClockTime capture_time)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (element);
GST_LOG_OBJECT (self, "Got video frame at %" GST_TIME_FORMAT,
GST_TIME_ARGS (capture_time));
g_mutex_lock (&self->lock);
if (!self->flushing) {
CaptureFrame *f;
while (g_queue_get_length (&self->current_frames) >= self->buffer_size) {
f = (CaptureFrame *) g_queue_pop_head (&self->current_frames);
GST_WARNING_OBJECT (self, "Dropping old frame at %" GST_TIME_FORMAT,
GST_TIME_ARGS (f->capture_time));
capture_frame_free (f);
}
f = (CaptureFrame *) g_malloc0 (sizeof (CaptureFrame));
f->frame = frame;
f->capture_time = capture_time;
f->mode = mode;
frame->AddRef ();
g_queue_push_tail (&self->current_frames, f);
g_cond_signal (&self->cond);
}
g_mutex_unlock (&self->lock);
}
static GstFlowReturn
gst_decklink_video_src_create (GstPushSrc * bsrc, GstBuffer ** buffer)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (bsrc);
GstFlowReturn flow_ret = GST_FLOW_OK;
const guint8 *data;
gsize data_size;
VideoFrame *vf;
CaptureFrame *f;
GstClockTime timestamp, duration;
GstCaps *caps;
g_mutex_lock (&self->lock);
while (g_queue_is_empty (&self->current_frames) && !self->flushing) {
g_cond_wait (&self->cond, &self->lock);
}
f = (CaptureFrame *) g_queue_pop_head (&self->current_frames);
g_mutex_unlock (&self->lock);
if (self->flushing) {
if (f)
capture_frame_free (f);
return GST_FLOW_FLUSHING;
}
g_mutex_lock (&self->lock);
if (self->mode == GST_DECKLINK_MODE_AUTO && self->caps_mode != f->mode) {
self->caps_mode = f->mode;
g_mutex_unlock (&self->lock);
g_mutex_lock (&self->input->lock);
self->input->mode = gst_decklink_get_mode (f->mode);
g_mutex_unlock (&self->input->lock);
caps = gst_decklink_mode_get_caps (f->mode);
gst_video_info_from_caps (&self->info, caps);
gst_base_src_set_caps (GST_BASE_SRC_CAST (bsrc), caps);
gst_element_post_message (GST_ELEMENT_CAST (self),
gst_message_new_latency (GST_OBJECT_CAST (self)));
gst_caps_unref (caps);
} else {
g_mutex_unlock (&self->lock);
}
f->frame->GetBytes ((gpointer *) & data);
data_size = self->info.size;
vf = (VideoFrame *) g_malloc0 (sizeof (VideoFrame));
*buffer =
gst_buffer_new_wrapped_full ((GstMemoryFlags) GST_MEMORY_FLAG_READONLY,
(gpointer) data, data_size, 0, data_size, vf,
(GDestroyNotify) video_frame_free);
vf->frame = f->frame;
f->frame->AddRef ();
vf->input = self->input->input;
vf->input->AddRef ();
duration =
gst_util_uint64_scale_int (GST_SECOND, self->info.fps_d,
self->info.fps_n);
// Our capture time is the end timestamp, subtract the
// duration to get the start timestamp
if (f->capture_time >= duration)
timestamp = f->capture_time - duration;
else
timestamp = 0;
GST_BUFFER_TIMESTAMP (*buffer) = timestamp;
GST_BUFFER_DURATION (*buffer) = duration;
capture_frame_free (f);
return flow_ret;
}
static gboolean
gst_decklink_video_src_query (GstBaseSrc * bsrc, GstQuery * query)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (bsrc);
gboolean ret = TRUE;
switch (GST_QUERY_TYPE (query)) {
case GST_QUERY_LATENCY:{
if (self->input) {
GstClockTime min, max;
const GstDecklinkMode *mode;
g_mutex_lock (&self->lock);
if (self->caps_mode != GST_DECKLINK_MODE_AUTO)
mode = gst_decklink_get_mode (self->caps_mode);
else
mode = gst_decklink_get_mode (self->mode);
g_mutex_unlock (&self->lock);
2015-01-08 11:13:03 +00:00
min = gst_util_uint64_scale_ceil (GST_SECOND, mode->fps_d, mode->fps_n);
max = self->buffer_size * min;
gst_query_set_latency (query, TRUE, min, max);
ret = TRUE;
} else {
ret = FALSE;
}
break;
}
default:
ret = GST_BASE_SRC_CLASS (parent_class)->query (bsrc, query);
break;
}
return ret;
}
static gboolean
gst_decklink_video_src_unlock (GstBaseSrc * bsrc)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (bsrc);
g_mutex_lock (&self->lock);
self->flushing = TRUE;
g_cond_signal (&self->cond);
g_mutex_unlock (&self->lock);
return TRUE;
}
static gboolean
gst_decklink_video_src_unlock_stop (GstBaseSrc * bsrc)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (bsrc);
g_mutex_lock (&self->lock);
self->flushing = FALSE;
g_queue_foreach (&self->current_frames, (GFunc) capture_frame_free, NULL);
g_queue_clear (&self->current_frames);
g_mutex_unlock (&self->lock);
return TRUE;
}
static gboolean
gst_decklink_video_src_open (GstDecklinkVideoSrc * self)
{
const GstDecklinkMode *mode;
GST_DEBUG_OBJECT (self, "Starting");
self->input =
gst_decklink_acquire_nth_input (self->device_number,
GST_ELEMENT_CAST (self), FALSE);
if (!self->input) {
GST_ERROR_OBJECT (self, "Failed to acquire input");
return FALSE;
}
mode = gst_decklink_get_mode (self->mode);
g_assert (mode != NULL);
g_mutex_lock (&self->input->lock);
self->input->mode = mode;
self->input->got_video_frame = gst_decklink_video_src_got_frame;
self->input->start_streams = gst_decklink_video_src_start_streams;
self->input->clock_start_time = GST_CLOCK_TIME_NONE;
self->input->clock_last_time = 0;
self->input->clock_offset = 0;
g_mutex_unlock (&self->input->lock);
return TRUE;
}
static gboolean
gst_decklink_video_src_close (GstDecklinkVideoSrc * self)
{
GST_DEBUG_OBJECT (self, "Stopping");
if (self->input) {
g_mutex_lock (&self->input->lock);
self->input->got_video_frame = NULL;
self->input->mode = NULL;
self->input->video_enabled = FALSE;
if (self->input->start_streams)
self->input->start_streams (self->input->videosrc);
g_mutex_unlock (&self->input->lock);
self->input->input->DisableVideoInput ();
gst_decklink_release_nth_input (self->device_number,
GST_ELEMENT_CAST (self), FALSE);
self->input = NULL;
}
return TRUE;
}
static void
gst_decklink_video_src_start_streams (GstElement * element)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (element);
HRESULT res;
if (self->input->video_enabled && (!self->input->audiosrc
|| self->input->audio_enabled)
&& (GST_STATE (self) == GST_STATE_PLAYING
|| GST_STATE_PENDING (self) == GST_STATE_PLAYING)) {
GST_DEBUG_OBJECT (self, "Starting streams");
res = self->input->input->StartStreams ();
if (res != S_OK) {
GST_ELEMENT_ERROR (self, STREAM, FAILED,
(NULL), ("Failed to start streams: 0x%08x", res));
return;
}
self->input->started = TRUE;
self->input->clock_restart = TRUE;
} else {
GST_DEBUG_OBJECT (self, "Not starting streams yet");
}
}
static GstStateChangeReturn
gst_decklink_video_src_change_state (GstElement * element,
GstStateChange transition)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (element);
GstStateChangeReturn ret;
switch (transition) {
case GST_STATE_CHANGE_NULL_TO_READY:
if (!gst_decklink_video_src_open (self)) {
ret = GST_STATE_CHANGE_FAILURE;
goto out;
}
break;
case GST_STATE_CHANGE_READY_TO_PAUSED:
g_mutex_lock (&self->input->lock);
self->input->clock_start_time = GST_CLOCK_TIME_NONE;
self->input->clock_last_time = 0;
self->input->clock_offset = 0;
g_mutex_unlock (&self->input->lock);
gst_element_post_message (element,
gst_message_new_clock_provide (GST_OBJECT_CAST (element),
self->input->clock, TRUE));
self->flushing = FALSE;
break;
case GST_STATE_CHANGE_PAUSED_TO_PLAYING:{
GstClock *clock;
clock = gst_element_get_clock (GST_ELEMENT_CAST (self));
if (clock && clock != self->input->clock) {
gst_clock_set_master (self->input->clock, clock);
}
if (clock)
gst_object_unref (clock);
break;
}
default:
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
if (ret == GST_STATE_CHANGE_FAILURE)
return ret;
switch (transition) {
case GST_STATE_CHANGE_PAUSED_TO_READY:
gst_element_post_message (element,
gst_message_new_clock_lost (GST_OBJECT_CAST (element),
self->input->clock));
gst_clock_set_master (self->input->clock, NULL);
g_mutex_lock (&self->input->lock);
self->input->clock_start_time = GST_CLOCK_TIME_NONE;
self->input->clock_last_time = 0;
self->input->clock_offset = 0;
g_mutex_unlock (&self->input->lock);
g_queue_foreach (&self->current_frames, (GFunc) capture_frame_free, NULL);
g_queue_clear (&self->current_frames);
self->caps_mode = GST_DECKLINK_MODE_AUTO;
break;
case GST_STATE_CHANGE_PLAYING_TO_PAUSED:{
HRESULT res;
GST_DEBUG_OBJECT (self, "Stopping streams");
g_mutex_lock (&self->input->lock);
self->input->started = FALSE;
g_mutex_unlock (&self->input->lock);
res = self->input->input->StopStreams ();
if (res != S_OK) {
GST_ELEMENT_ERROR (self, STREAM, FAILED,
(NULL), ("Failed to stop streams: 0x%08x", res));
ret = GST_STATE_CHANGE_FAILURE;
}
break;
}
case GST_STATE_CHANGE_PAUSED_TO_PLAYING:{
g_mutex_lock (&self->input->lock);
if (self->input->start_streams)
self->input->start_streams (self->input->videosrc);
g_mutex_unlock (&self->input->lock);
break;
}
case GST_STATE_CHANGE_READY_TO_NULL:
gst_decklink_video_src_close (self);
break;
default:
break;
}
out:
return ret;
}
static GstClock *
gst_decklink_video_src_provide_clock (GstElement * element)
{
GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (element);
if (!self->input)
return NULL;
return GST_CLOCK_CAST (gst_object_ref (self->input->clock));
}