gstreamer/gst/proxy/gstproxysrc.c
2021-04-11 16:16:55 +00:00

384 lines
12 KiB
C

/*
* Copyright (C) 2018 Centricular Ltd.
* Author: Sebastian Dröge <sebastian@centricular.com>
* Author: Nirbheek Chauhan <nirbheek@centricular.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 St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/**
* SECTION:element-proxysrc
* @title: proxysrc
*
* Proxysrc is a source element that proxies events, queries, and buffers from
* another pipeline that contains a matching proxysink element. The purpose is
* to allow two decoupled pipelines to function as though they are one without
* having to manually shuttle buffers, events, queries, etc between the two.
*
* The element queues buffers from the matching proxysink to an internal queue,
* so everything downstream is properly decoupled from the upstream pipeline.
* However, the queue may get filled up if the downstream pipeline does not
* accept buffers quickly enough; perhaps because it is not yet PLAYING.
*
* ## Usage
*
* |[<!-- language="C" -->
* GstElement *pipe1, *pipe2, *psink, *psrc;
* GstClock *clock;
*
* pipe1 = gst_parse_launch ("audiotestsrc ! proxysink name=psink", NULL);
* psink = gst_bin_get_by_name (GST_BIN (pipe1), "psink");
*
* pipe2 = gst_parse_launch ("proxysrc name=psrc ! autoaudiosink", NULL);
* psrc = gst_bin_get_by_name (GST_BIN (pipe2), "psrc");
*
* // Connect the two pipelines
* g_object_set (psrc, "proxysink", psink, NULL);
*
* // Both pipelines must agree on the timing information or we'll get glitches
* // or overruns/underruns. Ideally, we should tell pipe1 to use the same clock
* // as pipe2, but since that will be set asynchronously to the audio clock, it
* // is simpler and likely accurate enough to use the system clock for both
* // pipelines. If no element in either pipeline will provide a clock, this
* // is not needed.
* clock = gst_system_clock_obtain ();
* gst_pipeline_use_clock (GST_PIPELINE (pipe1), clock);
* gst_pipeline_use_clock (GST_PIPELINE (pipe2), clock);
* g_object_unref (clock);
*
* // This is not really needed in this case since the pipelines are created and
* // started at the same time. However, an application that dynamically
* // generates pipelines must ensure that all the pipelines that will be
* // connected together share the same base time.
* gst_element_set_base_time (pipe1, 0);
* gst_element_set_base_time (pipe2, 0);
*
* gst_element_set_state (pipe1, GST_STATE_PLAYING);
* gst_element_set_state (pipe2, GST_STATE_PLAYING);
* ]|
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "gstproxysrc.h"
#include "gstproxysink.h"
#include "gstproxy-priv.h"
#define GST_CAT_DEFAULT gst_proxy_src_debug
GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS_ANY);
enum
{
PROP_0,
PROP_PROXYSINK,
};
/* We're not subclassing from basesrc because we don't want any of the special
* handling it has for events/queries/etc. We just pass-through everything. */
/* Our parent type is a GstBin instead of GstElement because we contain a queue
* element */
#define parent_class gst_proxy_src_parent_class
G_DEFINE_TYPE (GstProxySrc, gst_proxy_src, GST_TYPE_BIN);
GST_ELEMENT_REGISTER_DEFINE (proxysrc, "proxysrc", GST_RANK_NONE,
GST_TYPE_PROXY_SRC);
static gboolean gst_proxy_src_internal_src_query (GstPad * pad,
GstObject * parent, GstQuery * query);
static gboolean gst_proxy_src_internal_src_event (GstPad * pad,
GstObject * parent, GstEvent * event);
static GstStateChangeReturn gst_proxy_src_change_state (GstElement * element,
GstStateChange transition);
static gboolean gst_proxy_src_send_event (GstElement * element,
GstEvent * event);
static gboolean gst_proxy_src_query (GstElement * element, GstQuery * query);
static void gst_proxy_src_dispose (GObject * object);
static void
gst_proxy_src_get_property (GObject * object, guint prop_id, GValue * value,
GParamSpec * spec)
{
GstProxySrc *self = GST_PROXY_SRC (object);
switch (prop_id) {
case PROP_PROXYSINK:
g_value_take_object (value, g_weak_ref_get (&self->proxysink));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, spec);
break;
}
}
static void
gst_proxy_src_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * spec)
{
GstProxySrc *self = GST_PROXY_SRC (object);
GstProxySink *sink;
switch (prop_id) {
case PROP_PROXYSINK:
sink = g_value_dup_object (value);
if (sink == NULL) {
/* Unset proxysrc property on the existing proxysink to break the
* connection in that direction */
GstProxySink *old_sink = g_weak_ref_get (&self->proxysink);
if (old_sink) {
gst_proxy_sink_set_proxysrc (old_sink, NULL);
g_object_unref (old_sink);
}
g_weak_ref_set (&self->proxysink, NULL);
} else {
/* Set proxysrc property on the new proxysink to point to us */
gst_proxy_sink_set_proxysrc (sink, self);
g_weak_ref_set (&self->proxysink, sink);
g_object_unref (sink);
}
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, spec);
}
}
static void
gst_proxy_src_class_init (GstProxySrcClass * klass)
{
GObjectClass *gobject_class = (GObjectClass *) klass;
GstElementClass *gstelement_class = (GstElementClass *) klass;
GST_DEBUG_CATEGORY_INIT (gst_proxy_src_debug, "proxysrc", 0, "proxy sink");
gobject_class->dispose = gst_proxy_src_dispose;
gobject_class->get_property = gst_proxy_src_get_property;
gobject_class->set_property = gst_proxy_src_set_property;
g_object_class_install_property (gobject_class, PROP_PROXYSINK,
g_param_spec_object ("proxysink", "Proxysink", "Matching proxysink",
GST_TYPE_PROXY_SINK, G_PARAM_READWRITE));
gstelement_class->change_state = gst_proxy_src_change_state;
gstelement_class->send_event = gst_proxy_src_send_event;
gstelement_class->query = gst_proxy_src_query;
gst_element_class_add_pad_template (gstelement_class,
gst_static_pad_template_get (&src_template));
gst_element_class_set_static_metadata (gstelement_class, "Proxy source",
"Source", "Proxy source for internal process communication",
"Sebastian Dröge <sebastian@centricular.com>");
}
static void
gst_proxy_src_init (GstProxySrc * self)
{
GstPad *srcpad, *sinkpad;
GstPadTemplate *templ;
GST_OBJECT_FLAG_SET (self, GST_ELEMENT_FLAG_SOURCE);
/* We feed incoming buffers into a queue to decouple the downstream pipeline
* from the upstream pipeline */
self->queue = gst_element_factory_make ("queue", NULL);
gst_bin_add (GST_BIN (self), self->queue);
srcpad = gst_element_get_static_pad (self->queue, "src");
templ = gst_static_pad_template_get (&src_template);
self->srcpad = gst_ghost_pad_new_from_template ("src", srcpad, templ);
gst_object_unref (templ);
gst_object_unref (srcpad);
gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
/* A dummy sinkpad that's not actually used anywhere
* Explanation for why this is needed is below */
self->dummy_sinkpad = gst_pad_new ("dummy_sinkpad", GST_PAD_SINK);
gst_object_set_parent (GST_OBJECT (self->dummy_sinkpad), GST_OBJECT (self));
self->internal_srcpad = gst_pad_new ("internal_src", GST_PAD_SRC);
gst_object_set_parent (GST_OBJECT (self->internal_srcpad),
GST_OBJECT (self->dummy_sinkpad));
gst_pad_set_event_function (self->internal_srcpad,
gst_proxy_src_internal_src_event);
gst_pad_set_query_function (self->internal_srcpad,
gst_proxy_src_internal_src_query);
/* We need to link internal_srcpad from proxysink to the sinkpad of our
* queue. However, two pads can only be linked if they share a common parent.
* Above, we set the parent of the dummy_sinkpad as proxysrc, and then we set
* the parent of internal_srcpad as dummy_sinkpad. This causes both these pads
* to share a parent allowing us to link them.
* Yes, this is a hack/workaround. */
sinkpad = gst_element_get_static_pad (self->queue, "sink");
gst_pad_link (self->internal_srcpad, sinkpad);
gst_object_unref (sinkpad);
gst_bin_set_suppressed_flags (GST_BIN (self),
GST_ELEMENT_FLAG_SOURCE | GST_ELEMENT_FLAG_SINK);
GST_OBJECT_FLAG_SET (self, GST_ELEMENT_FLAG_SOURCE);
}
static void
gst_proxy_src_dispose (GObject * object)
{
GstProxySrc *self = GST_PROXY_SRC (object);
gst_object_unparent (GST_OBJECT (self->dummy_sinkpad));
self->dummy_sinkpad = NULL;
gst_object_unparent (GST_OBJECT (self->internal_srcpad));
self->internal_srcpad = NULL;
g_weak_ref_set (&self->proxysink, NULL);
G_OBJECT_CLASS (gst_proxy_src_parent_class)->dispose (object);
}
static GstStateChangeReturn
gst_proxy_src_change_state (GstElement * element, GstStateChange transition)
{
GstElementClass *gstelement_class =
GST_ELEMENT_CLASS (gst_proxy_src_parent_class);
GstProxySrc *self = GST_PROXY_SRC (element);
GstStateChangeReturn ret;
ret = gstelement_class->change_state (element, transition);
if (ret == GST_STATE_CHANGE_FAILURE)
return ret;
switch (transition) {
case GST_STATE_CHANGE_READY_TO_PAUSED:
ret = GST_STATE_CHANGE_NO_PREROLL;
gst_pad_set_active (self->internal_srcpad, TRUE);
break;
case GST_STATE_CHANGE_PAUSED_TO_READY:
gst_pad_set_active (self->internal_srcpad, FALSE);
break;
default:
break;
}
return ret;
}
static gboolean
gst_proxy_src_send_event (GstElement * element, GstEvent * event)
{
GstProxySrc *self = GST_PROXY_SRC (element);
if (GST_EVENT_IS_DOWNSTREAM (event)) {
GstPad *sinkpad = gst_element_get_static_pad (self->queue, "sink");
gboolean ret;
ret = gst_pad_send_event (sinkpad, event);
gst_object_unref (sinkpad);
return ret;
} else {
gst_event_unref (event);
return FALSE;
}
}
static gboolean
gst_proxy_src_query (GstElement * element, GstQuery * query)
{
GstProxySrc *self = GST_PROXY_SRC (element);
if (GST_QUERY_IS_DOWNSTREAM (query)) {
GstPad *sinkpad = gst_element_get_static_pad (self->queue, "sink");
gboolean ret;
ret = gst_pad_query (sinkpad, query);
gst_object_unref (sinkpad);
return ret;
} else {
return FALSE;
}
}
static gboolean
gst_proxy_src_internal_src_query (GstPad * pad, GstObject * parent,
GstQuery * query)
{
GstProxySrc *self = GST_PROXY_SRC (gst_object_get_parent (parent));
GstProxySink *sink;
gboolean ret = FALSE;
if (!self)
return ret;
GST_LOG_OBJECT (pad, "Handling query of type '%s'",
gst_query_type_get_name (GST_QUERY_TYPE (query)));
sink = g_weak_ref_get (&self->proxysink);
if (sink) {
GstPad *sinkpad;
sinkpad = gst_proxy_sink_get_internal_sinkpad (sink);
ret = gst_pad_peer_query (sinkpad, query);
gst_object_unref (sinkpad);
gst_object_unref (sink);
}
gst_object_unref (self);
return ret;
}
static gboolean
gst_proxy_src_internal_src_event (GstPad * pad, GstObject * parent,
GstEvent * event)
{
GstProxySrc *self = GST_PROXY_SRC (gst_object_get_parent (parent));
GstProxySink *sink;
gboolean ret = FALSE;
if (!self)
return ret;
GST_LOG_OBJECT (pad, "Got %s event", GST_EVENT_TYPE_NAME (event));
sink = g_weak_ref_get (&self->proxysink);
if (sink) {
GstPad *sinkpad;
sinkpad = gst_proxy_sink_get_internal_sinkpad (sink);
ret = gst_pad_push_event (sinkpad, event);
gst_object_unref (sinkpad);
gst_object_unref (sink);
} else
gst_event_unref (event);
gst_object_unref (self);
return ret;
}
/* Wrapper function for accessing private member */
GstPad *
gst_proxy_src_get_internal_srcpad (GstProxySrc * self)
{
return gst_object_ref (self->internal_srcpad);
}