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RIST TR-06-1 is a specification for video streaming made by the VSF group. It is using a subset of RTP specification to which some modification has been made to improve RTX behaviour and avoid any need for signaling. The plugin implement ristrtxsend / ristrtxreceive element which are the RIST specific equivalent of rtprtxsend/rtprtxreceive and ristsink / ristsrc which implement rist transmitter and receiver. The RIST protocol is meant to be used in unidirectional way. Typically, MPEG TS over RTP is used. Currently we support unicast and multicast streaming according to the specification. This patch does not include any bonding support yet. The ristsrc element introduce rist:// URI handling in parallel to it's property configuration interface.
302 lines
8.9 KiB
C
302 lines
8.9 KiB
C
/* RTP Retransmission receiver element for GStreamer
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*
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* gstrtprtxreceive.c:
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*
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* Copyright (C) 2013-2019 Collabora Ltd.
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* @author Julien Isorce <julien.isorce@collabora.co.uk>
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* Nicolas Dufresne <nicolas.dufresne@collabora.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-ristrtxreceive
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* @title: ristrtxreceive
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* @see_also: ristrtxsend
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*
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* This element translates RIST RTX packets into its original form with the
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* %GST_RTP_BUFFER_FLAG_RETRANSMISSION flag set. This element is intented to
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* be used by ristsrc element.
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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 <gst/gst.h>
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#include <gst/rtp/gstrtpbuffer.h>
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#include "gstrist.h"
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GST_DEBUG_CATEGORY_STATIC (gst_rist_rtx_receive_debug);
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#define GST_CAT_DEFAULT gst_rist_rtx_receive_debug
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enum
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{
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PROP_0,
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PROP_NUM_RTX_REQUESTS,
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PROP_NUM_RTX_PACKETS,
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PROP_RIST
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};
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static GstStaticPadTemplate src_factory = 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 ("application/x-rtp")
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);
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static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
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GST_PAD_SINK,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("application/x-rtp")
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);
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struct _GstRistRtxReceive
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{
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GstElement element;
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/* pad */
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GstPad *sinkpad;
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GstPad *srcpad;
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/* statistics */
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guint num_rtx_requests;
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guint num_rtx_packets;
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GstClockTime last_time;
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};
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static gboolean gst_rist_rtx_receive_src_event (GstPad * pad,
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GstObject * parent, GstEvent * event);
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static GstFlowReturn gst_rist_rtx_receive_chain (GstPad * pad,
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GstObject * parent, GstBuffer * buffer);
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static GstStateChangeReturn gst_rist_rtx_receive_change_state (GstElement *
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element, GstStateChange transition);
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static void gst_rist_rtx_receive_get_property (GObject * object, guint prop_id,
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GValue * value, GParamSpec * pspec);
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G_DEFINE_TYPE_WITH_CODE (GstRistRtxReceive, gst_rist_rtx_receive,
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GST_TYPE_ELEMENT, GST_DEBUG_CATEGORY_INIT (gst_rist_rtx_receive_debug,
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"ristrtxreceive", 0, "RIST retransmission receiver"));
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static void
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gst_rist_rtx_receive_class_init (GstRistRtxReceiveClass * klass)
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{
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GObjectClass *gobject_class;
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GstElementClass *gstelement_class;
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gobject_class = (GObjectClass *) klass;
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gstelement_class = (GstElementClass *) klass;
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gobject_class->get_property = gst_rist_rtx_receive_get_property;
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g_object_class_install_property (gobject_class, PROP_NUM_RTX_REQUESTS,
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g_param_spec_uint ("num-rtx-requests", "Num RTX Requests",
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"Number of retransmission events received", 0, G_MAXUINT,
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0, G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
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g_object_class_install_property (gobject_class, PROP_NUM_RTX_PACKETS,
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g_param_spec_uint ("num-rtx-packets", "Num RTX Packets",
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" Number of retransmission packets received", 0, G_MAXUINT,
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0, G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
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gst_element_class_add_static_pad_template (gstelement_class, &src_factory);
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gst_element_class_add_static_pad_template (gstelement_class, &sink_factory);
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gst_element_class_set_static_metadata (gstelement_class,
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"RIST Retransmission receiver", "Codec",
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"Receive retransmitted RIST packets according to VSF TR-06-1",
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"Nicolas Dufresne <nicolas.dufresne@collabora.com>");
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gstelement_class->change_state =
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GST_DEBUG_FUNCPTR (gst_rist_rtx_receive_change_state);
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}
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static void
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gst_rist_rtx_receive_reset (GstRistRtxReceive * rtx)
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{
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GST_OBJECT_LOCK (rtx);
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rtx->num_rtx_requests = 0;
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rtx->num_rtx_packets = 0;
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GST_OBJECT_UNLOCK (rtx);
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}
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static void
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gst_rist_rtx_receive_init (GstRistRtxReceive * rtx)
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{
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GstElementClass *klass = GST_ELEMENT_GET_CLASS (rtx);
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rtx->srcpad =
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gst_pad_new_from_template (gst_element_class_get_pad_template (klass,
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"src"), "src");
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GST_PAD_SET_PROXY_CAPS (rtx->srcpad);
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GST_PAD_SET_PROXY_ALLOCATION (rtx->srcpad);
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gst_pad_set_event_function (rtx->srcpad,
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GST_DEBUG_FUNCPTR (gst_rist_rtx_receive_src_event));
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gst_element_add_pad (GST_ELEMENT (rtx), rtx->srcpad);
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rtx->sinkpad =
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gst_pad_new_from_template (gst_element_class_get_pad_template (klass,
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"sink"), "sink");
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GST_PAD_SET_PROXY_CAPS (rtx->sinkpad);
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GST_PAD_SET_PROXY_ALLOCATION (rtx->sinkpad);
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gst_pad_set_chain_function (rtx->sinkpad,
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GST_DEBUG_FUNCPTR (gst_rist_rtx_receive_chain));
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gst_element_add_pad (GST_ELEMENT (rtx), rtx->sinkpad);
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}
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static gboolean
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gst_rist_rtx_receive_src_event (GstPad * pad, GstObject * parent,
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GstEvent * event)
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{
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GstRistRtxReceive *rtx = GST_RIST_RTX_RECEIVE (parent);
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switch (GST_EVENT_TYPE (event)) {
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case GST_EVENT_CUSTOM_UPSTREAM:
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{
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const GstStructure *s = gst_event_get_structure (event);
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/* This event usually comes from the downstream gstrtpjitterbuffer */
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if (gst_structure_has_name (s, "GstRTPRetransmissionRequest")) {
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#ifndef GST_DISABLE_GST_DEBUG
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guint seqnum = 0;
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guint ssrc = 0;
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/* retrieve seqnum of the packet that need to be retransmitted */
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if (!gst_structure_get_uint (s, "seqnum", &seqnum))
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seqnum = -1;
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/* retrieve ssrc of the packet that need to be retransmitted
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* it's useful when reconstructing the original packet from the rtx packet */
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if (!gst_structure_get_uint (s, "ssrc", &ssrc))
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ssrc = -1;
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GST_DEBUG_OBJECT (rtx, "got rtx request for seqnum: %u, ssrc: %X",
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seqnum, ssrc);
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#endif
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GST_OBJECT_LOCK (rtx);
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/* increase number of seen requests for our statistics */
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++rtx->num_rtx_requests;
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GST_OBJECT_UNLOCK (rtx);
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}
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break;
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}
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default:
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break;
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}
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return gst_pad_event_default (pad, parent, event);
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}
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static GstFlowReturn
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gst_rist_rtx_receive_chain (GstPad * pad, GstObject * parent,
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GstBuffer * buffer)
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{
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GstRistRtxReceive *rtx = GST_RIST_RTX_RECEIVE (parent);
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GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
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guint32 ssrc = 0;
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guint16 seqnum = 0;
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gboolean is_rtx;
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/* map current rtp packet to parse its header */
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if (!gst_rtp_buffer_map (buffer, GST_MAP_READ, &rtp))
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goto invalid_buffer;
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ssrc = gst_rtp_buffer_get_ssrc (&rtp);
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seqnum = gst_rtp_buffer_get_seq (&rtp);
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/* check if we have a retransmission packet (this information comes from SDP) */
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GST_OBJECT_LOCK (rtx);
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/* RIST sets SSRC LSB to 1 to indicate an RTC packet */
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is_rtx = ssrc & 0x1;
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rtx->last_time = GST_BUFFER_PTS (buffer);
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if (is_rtx)
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/* increase our statistic */
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++rtx->num_rtx_packets;
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GST_OBJECT_UNLOCK (rtx);
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/* create the retransmission packet */
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if (is_rtx) {
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GST_DEBUG_OBJECT (rtx,
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"Recovered packet from RIST RTX seqnum:%u ssrc: %u",
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gst_rtp_buffer_get_seq (&rtp), gst_rtp_buffer_get_ssrc (&rtp));
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gst_rtp_buffer_set_ssrc (&rtp, ssrc & 0xFFFFFFFE);
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GST_BUFFER_FLAG_SET (buffer, GST_RTP_BUFFER_FLAG_RETRANSMISSION);
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}
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gst_rtp_buffer_unmap (&rtp);
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GST_TRACE_OBJECT (rtx, "pushing packet seqnum:%u from master stream "
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"ssrc: %X", seqnum, ssrc);
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return gst_pad_push (rtx->srcpad, buffer);
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invalid_buffer:
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{
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GST_ELEMENT_WARNING (rtx, STREAM, DECODE, (NULL),
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("Received invalid RTP payload, dropping"));
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gst_buffer_unref (buffer);
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return GST_FLOW_OK;
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}
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}
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static void
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gst_rist_rtx_receive_get_property (GObject * object,
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guint prop_id, GValue * value, GParamSpec * pspec)
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{
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GstRistRtxReceive *rtx = GST_RIST_RTX_RECEIVE (object);
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switch (prop_id) {
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case PROP_NUM_RTX_REQUESTS:
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GST_OBJECT_LOCK (rtx);
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g_value_set_uint (value, rtx->num_rtx_requests);
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GST_OBJECT_UNLOCK (rtx);
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break;
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case PROP_NUM_RTX_PACKETS:
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GST_OBJECT_LOCK (rtx);
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g_value_set_uint (value, rtx->num_rtx_packets);
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GST_OBJECT_UNLOCK (rtx);
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break;
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default:
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G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
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break;
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}
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}
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static GstStateChangeReturn
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gst_rist_rtx_receive_change_state (GstElement * element,
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GstStateChange transition)
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{
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GstRistRtxReceive *rtx = GST_RIST_RTX_RECEIVE (element);
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GstStateChangeReturn ret;
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ret =
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GST_ELEMENT_CLASS (gst_rist_rtx_receive_parent_class)->change_state
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(element, transition);
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switch (transition) {
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case GST_STATE_CHANGE_PAUSED_TO_READY:
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gst_rist_rtx_receive_reset (rtx);
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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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