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382 lines
12 KiB
C
382 lines
12 KiB
C
/*
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* Copyright (C) 2018 Centricular Ltd.
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* Author: Sebastian Dröge <sebastian@centricular.com>
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* Author: Nirbheek Chauhan <nirbheek@centricular.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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/**
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* SECTION:element-proxysrc
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* @title: proxysrc
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*
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* Proxysrc is a source element that proxies events, queries, and buffers from
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* another pipeline that contains a matching proxysink element. The purpose is
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* to allow two decoupled pipelines to function as though they are one without
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* having to manually shuttle buffers, events, queries, etc between the two.
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*
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* The element queues buffers from the matching proxysink to an internal queue,
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* so everything downstream is properly decoupled from the upstream pipeline.
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* However, the queue may get filled up if the downstream pipeline does not
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* accept buffers quickly enough; perhaps because it is not yet PLAYING.
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*
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* ## Usage
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*
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* |[<!-- language="C" -->
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* GstElement *pipe1, *pipe2, *psink, *psrc;
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* GstClock *clock;
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*
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* pipe1 = gst_parse_launch ("audiotestsrc ! proxysink name=psink", NULL);
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* psink = gst_bin_get_by_name (GST_BIN (pipe1), "psink");
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*
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* pipe2 = gst_parse_launch ("proxysrc name=psrc ! autoaudiosink", NULL);
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* psrc = gst_bin_get_by_name (GST_BIN (pipe2), "psrc");
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*
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* // Connect the two pipelines
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* g_object_set (psrc, "proxysink", psink, NULL);
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*
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* // Both pipelines must agree on the timing information or we'll get glitches
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* // or overruns/underruns. Ideally, we should tell pipe1 to use the same clock
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* // as pipe2, but since that will be set asynchronously to the audio clock, it
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* // is simpler and likely accurate enough to use the system clock for both
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* // pipelines. If no element in either pipeline will provide a clock, this
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* // is not needed.
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* clock = gst_system_clock_obtain ();
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* gst_pipeline_use_clock (GST_PIPELINE (pipe1), clock);
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* gst_pipeline_use_clock (GST_PIPELINE (pipe2), clock);
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* g_object_unref (clock);
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*
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* // This is not really needed in this case since the pipelines are created and
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* // started at the same time. However, an application that dynamically
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* // generates pipelines must ensure that all the pipelines that will be
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* // connected together share the same base time.
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* gst_element_set_base_time (pipe1, 0);
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* gst_element_set_base_time (pipe2, 0);
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*
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* gst_element_set_state (pipe1, GST_STATE_PLAYING);
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* gst_element_set_state (pipe2, GST_STATE_PLAYING);
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* ]|
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "gstproxysrc.h"
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#include "gstproxysink.h"
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#include "gstproxy-priv.h"
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#define GST_CAT_DEFAULT gst_proxy_src_debug
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GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
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static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
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GST_PAD_SRC,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS_ANY);
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enum
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{
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PROP_0,
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PROP_PROXYSINK,
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};
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/* We're not subclassing from basesrc because we don't want any of the special
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* handling it has for events/queries/etc. We just pass-through everything. */
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/* Our parent type is a GstBin instead of GstElement because we contain a queue
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* element */
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#define parent_class gst_proxy_src_parent_class
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G_DEFINE_TYPE (GstProxySrc, gst_proxy_src, GST_TYPE_BIN);
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static gboolean gst_proxy_src_internal_src_query (GstPad * pad,
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GstObject * parent, GstQuery * query);
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static gboolean gst_proxy_src_internal_src_event (GstPad * pad,
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GstObject * parent, GstEvent * event);
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static GstStateChangeReturn gst_proxy_src_change_state (GstElement * element,
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GstStateChange transition);
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static gboolean gst_proxy_src_send_event (GstElement * element,
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GstEvent * event);
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static gboolean gst_proxy_src_query (GstElement * element, GstQuery * query);
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static void gst_proxy_src_dispose (GObject * object);
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static void
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gst_proxy_src_get_property (GObject * object, guint prop_id, GValue * value,
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GParamSpec * spec)
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{
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GstProxySrc *self = GST_PROXY_SRC (object);
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switch (prop_id) {
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case PROP_PROXYSINK:
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g_value_take_object (value, g_weak_ref_get (&self->proxysink));
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break;
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default:
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G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, spec);
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break;
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}
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}
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static void
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gst_proxy_src_set_property (GObject * object, guint prop_id,
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const GValue * value, GParamSpec * spec)
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{
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GstProxySrc *self = GST_PROXY_SRC (object);
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GstProxySink *sink;
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switch (prop_id) {
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case PROP_PROXYSINK:
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sink = g_value_dup_object (value);
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if (sink == NULL) {
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/* Unset proxysrc property on the existing proxysink to break the
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* connection in that direction */
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GstProxySink *old_sink = g_weak_ref_get (&self->proxysink);
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if (old_sink) {
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gst_proxy_sink_set_proxysrc (old_sink, NULL);
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g_object_unref (old_sink);
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}
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g_weak_ref_set (&self->proxysink, NULL);
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} else {
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/* Set proxysrc property on the new proxysink to point to us */
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gst_proxy_sink_set_proxysrc (sink, self);
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g_weak_ref_set (&self->proxysink, sink);
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g_object_unref (sink);
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}
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break;
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default:
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G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, spec);
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}
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}
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static void
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gst_proxy_src_class_init (GstProxySrcClass * klass)
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{
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GObjectClass *gobject_class = (GObjectClass *) klass;
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GstElementClass *gstelement_class = (GstElementClass *) klass;
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GST_DEBUG_CATEGORY_INIT (gst_proxy_src_debug, "proxysrc", 0, "proxy sink");
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gobject_class->dispose = gst_proxy_src_dispose;
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gobject_class->get_property = gst_proxy_src_get_property;
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gobject_class->set_property = gst_proxy_src_set_property;
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g_object_class_install_property (gobject_class, PROP_PROXYSINK,
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g_param_spec_object ("proxysink", "Proxysink", "Matching proxysink",
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GST_TYPE_PROXY_SINK, G_PARAM_READWRITE));
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gstelement_class->change_state = gst_proxy_src_change_state;
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gstelement_class->send_event = gst_proxy_src_send_event;
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gstelement_class->query = gst_proxy_src_query;
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gst_element_class_add_pad_template (gstelement_class,
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gst_static_pad_template_get (&src_template));
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gst_element_class_set_static_metadata (gstelement_class, "Proxy source",
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"Source", "Proxy source for internal process communication",
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"Sebastian Dröge <sebastian@centricular.com>");
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}
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static void
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gst_proxy_src_init (GstProxySrc * self)
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{
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GstPad *srcpad, *sinkpad;
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GstPadTemplate *templ;
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GST_OBJECT_FLAG_SET (self, GST_ELEMENT_FLAG_SOURCE);
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/* We feed incoming buffers into a queue to decouple the downstream pipeline
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* from the upstream pipeline */
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self->queue = gst_element_factory_make ("queue", NULL);
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gst_bin_add (GST_BIN (self), self->queue);
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srcpad = gst_element_get_static_pad (self->queue, "src");
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templ = gst_static_pad_template_get (&src_template);
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self->srcpad = gst_ghost_pad_new_from_template ("src", srcpad, templ);
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gst_object_unref (templ);
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gst_object_unref (srcpad);
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gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
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/* A dummy sinkpad that's not actually used anywhere
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* Explanation for why this is needed is below */
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self->dummy_sinkpad = gst_pad_new ("dummy_sinkpad", GST_PAD_SINK);
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gst_object_set_parent (GST_OBJECT (self->dummy_sinkpad), GST_OBJECT (self));
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self->internal_srcpad = gst_pad_new ("internal_src", GST_PAD_SRC);
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gst_object_set_parent (GST_OBJECT (self->internal_srcpad),
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GST_OBJECT (self->dummy_sinkpad));
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gst_pad_set_event_function (self->internal_srcpad,
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gst_proxy_src_internal_src_event);
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gst_pad_set_query_function (self->internal_srcpad,
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gst_proxy_src_internal_src_query);
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/* We need to link internal_srcpad from proxysink to the sinkpad of our
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* queue. However, two pads can only be linked if they share a common parent.
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* Above, we set the parent of the dummy_sinkpad as proxysrc, and then we set
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* the parent of internal_srcpad as dummy_sinkpad. This causes both these pads
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* to share a parent allowing us to link them.
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* Yes, this is a hack/workaround. */
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sinkpad = gst_element_get_static_pad (self->queue, "sink");
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gst_pad_link (self->internal_srcpad, sinkpad);
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gst_object_unref (sinkpad);
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gst_bin_set_suppressed_flags (GST_BIN (self),
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GST_ELEMENT_FLAG_SOURCE | GST_ELEMENT_FLAG_SINK);
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GST_OBJECT_FLAG_SET (self, GST_ELEMENT_FLAG_SOURCE);
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}
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static void
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gst_proxy_src_dispose (GObject * object)
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{
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GstProxySrc *self = GST_PROXY_SRC (object);
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gst_object_unparent (GST_OBJECT (self->dummy_sinkpad));
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self->dummy_sinkpad = NULL;
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gst_object_unparent (GST_OBJECT (self->internal_srcpad));
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self->internal_srcpad = NULL;
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g_weak_ref_set (&self->proxysink, NULL);
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G_OBJECT_CLASS (gst_proxy_src_parent_class)->dispose (object);
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}
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static GstStateChangeReturn
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gst_proxy_src_change_state (GstElement * element, GstStateChange transition)
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{
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GstElementClass *gstelement_class =
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GST_ELEMENT_CLASS (gst_proxy_src_parent_class);
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GstProxySrc *self = GST_PROXY_SRC (element);
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GstStateChangeReturn ret;
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ret = gstelement_class->change_state (element, transition);
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if (ret == GST_STATE_CHANGE_FAILURE)
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return ret;
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switch (transition) {
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case GST_STATE_CHANGE_READY_TO_PAUSED:
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ret = GST_STATE_CHANGE_NO_PREROLL;
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gst_pad_set_active (self->internal_srcpad, TRUE);
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break;
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case GST_STATE_CHANGE_PAUSED_TO_READY:
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gst_pad_set_active (self->internal_srcpad, FALSE);
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break;
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default:
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break;
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}
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return ret;
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}
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static gboolean
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gst_proxy_src_send_event (GstElement * element, GstEvent * event)
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{
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GstProxySrc *self = GST_PROXY_SRC (element);
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if (GST_EVENT_IS_DOWNSTREAM (event)) {
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GstPad *sinkpad = gst_element_get_static_pad (self->queue, "sink");
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gboolean ret;
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ret = gst_pad_send_event (sinkpad, event);
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gst_object_unref (sinkpad);
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return ret;
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} else {
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gst_event_unref (event);
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return FALSE;
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}
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}
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static gboolean
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gst_proxy_src_query (GstElement * element, GstQuery * query)
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{
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GstProxySrc *self = GST_PROXY_SRC (element);
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if (GST_QUERY_IS_DOWNSTREAM (query)) {
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GstPad *sinkpad = gst_element_get_static_pad (self->queue, "sink");
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gboolean ret;
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ret = gst_pad_query (sinkpad, query);
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gst_object_unref (sinkpad);
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return ret;
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} else {
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return FALSE;
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}
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}
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static gboolean
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gst_proxy_src_internal_src_query (GstPad * pad, GstObject * parent,
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GstQuery * query)
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{
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GstProxySrc *self = GST_PROXY_SRC (gst_object_get_parent (parent));
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GstProxySink *sink;
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gboolean ret = FALSE;
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if (!self)
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return ret;
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GST_LOG_OBJECT (pad, "Handling query of type '%s'",
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gst_query_type_get_name (GST_QUERY_TYPE (query)));
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sink = g_weak_ref_get (&self->proxysink);
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if (sink) {
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GstPad *sinkpad;
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sinkpad = gst_proxy_sink_get_internal_sinkpad (sink);
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ret = gst_pad_peer_query (sinkpad, query);
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gst_object_unref (sinkpad);
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gst_object_unref (sink);
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}
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gst_object_unref (self);
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return ret;
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}
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static gboolean
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gst_proxy_src_internal_src_event (GstPad * pad, GstObject * parent,
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GstEvent * event)
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{
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GstProxySrc *self = GST_PROXY_SRC (gst_object_get_parent (parent));
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GstProxySink *sink;
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gboolean ret = FALSE;
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if (!self)
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return ret;
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GST_LOG_OBJECT (pad, "Got %s event", GST_EVENT_TYPE_NAME (event));
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sink = g_weak_ref_get (&self->proxysink);
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if (sink) {
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GstPad *sinkpad;
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sinkpad = gst_proxy_sink_get_internal_sinkpad (sink);
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ret = gst_pad_push_event (sinkpad, event);
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gst_object_unref (sinkpad);
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gst_object_unref (sink);
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} else
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gst_event_unref (event);
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gst_object_unref (self);
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return ret;
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}
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/* Wrapper function for accessing private member */
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GstPad *
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gst_proxy_src_get_internal_srcpad (GstProxySrc * self)
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{
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return gst_object_ref (self->internal_srcpad);
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}
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