gstreamer/gst/rtpmanager/gstrtpfunnel.c

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/* RTP funnel element for GStreamer
*
* gstrtpfunnel.c:
*
* Copyright (C) <2017> Pexip.
* Contact: Havard Graff <havard@pexip.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-rtpfunnel
* @title: rtpfunnel
* @see_also: rtpbasepaylaoder, rtpsession
*
* RTP funnel is basically like a normal funnel with a few added
* functionalities to support bundling.
*
* Bundle is the concept of sending multiple streams in a single RTP session.
* These can be both audio and video streams, and several of both.
* One of the advantages with bundling is that you can get away with fewer
* ports for sending and receiving media. Also the RTCP traffic gets more
* compact if you can report on multiple streams in a single sender/receiver
* report.
*
* One of the reasons for a specialized RTP funnel is that some messages
* coming upstream want to find their way back to the right stream,
* and a normal funnel can't know which of its sinkpads it should send
* these messages to. The RTP funnel achieves this by keeping track of the
* SSRC of each stream on its sinkpad, and then uses the fact that upstream
* events are tagged inside rtpbin with the appropriate SSRC, so that upon
* receiving such an event, the RTP funnel can do a simple lookup for the
* right pad to forward the event to.
*
* A good example here is the KeyUnit event. If several video encoders are
* being bundled together using the RTP funnel, and one of the decoders on
* the receiving side asks for a KeyUnit, typically a RTCP PLI message will
* be sent from the receiver to the sender, and this will be transformed into
* a GstForceKeyUnit event inside GstRTPSession, and sent upstream. The
* RTP funnel can than make sure that this event hits the right encoder based
* on the SSRC embedded in the event.
*
* Another feature of the RTP funnel is that it will mux together TWCC
* (Transport-Wide Congestion Control) sequence-numbers. The point being that
* it should increment "transport-wide", meaning potentially several
* bundled streams. Note that not *all* streams being bundled needs to be
* affected by this. As an example Google WebRTC will use bundle with audio
* and video, but will only use TWCC sequence-numbers for the video-stream(s).
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/rtp/gstrtpbuffer.h>
#include "gstrtpfunnel.h"
GST_DEBUG_CATEGORY_STATIC (gst_rtp_funnel_debug);
#define GST_CAT_DEFAULT gst_rtp_funnel_debug
#define TWCC_EXTMAP_STR "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01"
/**************** GstRTPFunnelPad ****************/
struct _GstRtpFunnelPadClass
{
GstPadClass class;
};
struct _GstRtpFunnelPad
{
GstPad pad;
guint32 ssrc;
gboolean has_twcc;
};
G_DEFINE_TYPE (GstRtpFunnelPad, gst_rtp_funnel_pad, GST_TYPE_PAD);
static void
gst_rtp_funnel_pad_class_init (G_GNUC_UNUSED GstRtpFunnelPadClass * klass)
{
}
static void
gst_rtp_funnel_pad_init (G_GNUC_UNUSED GstRtpFunnelPad * pad)
{
}
/**************** GstRTPFunnel ****************/
enum
{
PROP_0,
PROP_COMMON_TS_OFFSET,
};
#define DEFAULT_COMMON_TS_OFFSET -1
struct _GstRtpFunnelClass
{
GstElementClass class;
};
struct _GstRtpFunnel
{
GstElement element;
GstPad *srcpad;
GstCaps *srccaps; /* protected by OBJECT_LOCK */
gboolean send_sticky_events;
GHashTable *ssrc_to_pad; /* protected by OBJECT_LOCK */
/* The last pad data was chained on */
GstPad *current_pad;
guint8 twcc_ext_id; /* the negotiated twcc extmap id */
guint16 twcc_seqnum; /* our internal twcc seqnum */
guint twcc_pads; /* numer of sinkpads with negotiated twcc */
/* properties */
gint common_ts_offset;
};
#define RTP_CAPS "application/x-rtp"
static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink_%u",
GST_PAD_SINK,
GST_PAD_REQUEST,
GST_STATIC_CAPS (RTP_CAPS));
static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS (RTP_CAPS));
#define gst_rtp_funnel_parent_class parent_class
G_DEFINE_TYPE (GstRtpFunnel, gst_rtp_funnel, GST_TYPE_ELEMENT);
static void
gst_rtp_funnel_send_sticky (GstRtpFunnel * funnel, GstPad * pad)
{
GstEvent *stream_start;
GstCaps *caps;
GstEvent *caps_ev;
if (!funnel->send_sticky_events)
goto done;
stream_start = gst_pad_get_sticky_event (pad, GST_EVENT_STREAM_START, 0);
if (stream_start && !gst_pad_push_event (funnel->srcpad, stream_start)) {
GST_ERROR_OBJECT (funnel, "Could not push stream start");
goto done;
}
/* We modify these caps in our sink pad event handlers, so make sure to
* send a copy downstream so that we can keep our internal caps writable */
GST_OBJECT_LOCK (funnel);
caps = gst_caps_copy (funnel->srccaps);
GST_OBJECT_UNLOCK (funnel);
caps_ev = gst_event_new_caps (caps);
gst_caps_unref (caps);
if (caps_ev && !gst_pad_push_event (funnel->srcpad, caps_ev)) {
GST_ERROR_OBJECT (funnel, "Could not push caps");
goto done;
}
funnel->send_sticky_events = FALSE;
done:
return;
}
static void
gst_rtp_funnel_forward_segment (GstRtpFunnel * funnel, GstPad * pad)
{
GstEvent *event;
guint i;
if (pad == funnel->current_pad) {
goto done;
}
event = gst_pad_get_sticky_event (pad, GST_EVENT_SEGMENT, 0);
if (event && !gst_pad_push_event (funnel->srcpad, event)) {
GST_ERROR_OBJECT (funnel, "Could not push segment");
goto done;
}
for (i = 0;; i++) {
event = gst_pad_get_sticky_event (pad, GST_EVENT_CUSTOM_DOWNSTREAM_STICKY,
i);
if (event == NULL)
break;
if (!gst_pad_push_event (funnel->srcpad, event))
GST_ERROR_OBJECT (funnel, "Could not push custom event");
}
funnel->current_pad = pad;
done:
return;
}
static void
gst_rtp_funnel_set_twcc_seqnum (GstRtpFunnel * funnel,
GstPad * pad, GstBuffer ** buf)
{
GstRtpFunnelPad *fpad = GST_RTP_FUNNEL_PAD_CAST (pad);
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
if (!funnel->twcc_ext_id || !fpad->has_twcc)
return;
*buf = gst_buffer_make_writable (*buf);
if (gst_rtp_buffer_map (*buf, GST_MAP_READWRITE, &rtp)) {
gpointer data;
/* if there already is a twcc-seqnum inside the packet */
if (gst_rtp_buffer_get_extension_onebyte_header (&rtp, funnel->twcc_ext_id,
0, &data, NULL)) {
/* with only one pad, we read the twcc-seqnum instead of writing it */
if (funnel->twcc_pads == 1) {
funnel->twcc_seqnum = GST_READ_UINT16_BE (data);
} else {
GST_WRITE_UINT16_BE (data, funnel->twcc_seqnum);
}
} else {
guint16 seq_be;
GST_WRITE_UINT16_BE (&seq_be, funnel->twcc_seqnum);
gst_rtp_buffer_add_extension_onebyte_header (&rtp, funnel->twcc_ext_id,
&seq_be, 2);
}
}
gst_rtp_buffer_unmap (&rtp);
funnel->twcc_seqnum++;
}
static GstFlowReturn
gst_rtp_funnel_sink_chain_object (GstPad * pad, GstRtpFunnel * funnel,
gboolean is_list, GstMiniObject * obj)
{
GstFlowReturn res;
GST_DEBUG_OBJECT (pad, "received %" GST_PTR_FORMAT, obj);
GST_PAD_STREAM_LOCK (funnel->srcpad);
gst_rtp_funnel_send_sticky (funnel, pad);
gst_rtp_funnel_forward_segment (funnel, pad);
if (is_list) {
res = gst_pad_push_list (funnel->srcpad, GST_BUFFER_LIST_CAST (obj));
} else {
GstBuffer *buf = GST_BUFFER_CAST (obj);
gst_rtp_funnel_set_twcc_seqnum (funnel, pad, &buf);
res = gst_pad_push (funnel->srcpad, buf);
}
GST_PAD_STREAM_UNLOCK (funnel->srcpad);
return res;
}
static GstFlowReturn
gst_rtp_funnel_sink_chain_list (GstPad * pad, GstObject * parent,
GstBufferList * list)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (parent);
return gst_rtp_funnel_sink_chain_object (pad, funnel, TRUE,
GST_MINI_OBJECT_CAST (list));
}
static GstFlowReturn
gst_rtp_funnel_sink_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (parent);
return gst_rtp_funnel_sink_chain_object (pad, funnel, FALSE,
GST_MINI_OBJECT_CAST (buffer));
}
static void
gst_rtp_funnel_set_twcc_ext_id (GstRtpFunnel * funnel, guint8 twcc_ext_id)
{
gchar *name;
if (funnel->twcc_ext_id == twcc_ext_id)
return;
name = g_strdup_printf ("extmap-%u", twcc_ext_id);
GST_OBJECT_LOCK (funnel);
gst_caps_set_simple (funnel->srccaps, name, G_TYPE_STRING, TWCC_EXTMAP_STR,
NULL);
GST_OBJECT_UNLOCK (funnel);
g_free (name);
/* make sure we update the sticky with the new caps */
funnel->send_sticky_events = TRUE;
GST_INFO_OBJECT (funnel, "Setting twcc-ext-id to %u", twcc_ext_id);
funnel->twcc_ext_id = twcc_ext_id;
}
static guint8
_get_extmap_id_for_attribute (const GstStructure * s, const gchar * ext_name)
{
guint i;
guint8 extmap_id = 0;
guint n_fields = gst_structure_n_fields (s);
for (i = 0; i < n_fields; i++) {
const gchar *field_name = gst_structure_nth_field_name (s, i);
if (g_str_has_prefix (field_name, "extmap-")) {
const gchar *str = gst_structure_get_string (s, field_name);
if (str && g_strcmp0 (str, ext_name) == 0) {
gint64 id = g_ascii_strtoll (field_name + 7, NULL, 10);
if (id > 0 && id < 15) {
extmap_id = id;
break;
}
}
}
}
return extmap_id;
}
static gboolean
gst_rtp_funnel_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (parent);
GstRtpFunnelPad *fpad = GST_RTP_FUNNEL_PAD_CAST (pad);
gboolean forward = TRUE;
gboolean ret = TRUE;
GST_DEBUG_OBJECT (pad, "received event %" GST_PTR_FORMAT, event);
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_STREAM_START:
case GST_EVENT_SEGMENT:
forward = FALSE;
break;
case GST_EVENT_CAPS:
{
GstCaps *caps;
GstStructure *s;
guint ssrc;
guint8 ext_id;
gst_event_parse_caps (event, &caps);
GST_OBJECT_LOCK (funnel);
if (!gst_caps_can_intersect (funnel->srccaps, caps)) {
GST_ERROR_OBJECT (funnel, "Can't intersect with caps %" GST_PTR_FORMAT,
caps);
g_assert_not_reached ();
}
GST_OBJECT_UNLOCK (funnel);
s = gst_caps_get_structure (caps, 0);
if (gst_structure_get_uint (s, "ssrc", &ssrc)) {
fpad->ssrc = ssrc;
GST_DEBUG_OBJECT (pad, "Got ssrc: %u", ssrc);
GST_OBJECT_LOCK (funnel);
g_hash_table_insert (funnel->ssrc_to_pad, GUINT_TO_POINTER (ssrc), pad);
GST_OBJECT_UNLOCK (funnel);
}
ext_id = _get_extmap_id_for_attribute (s, TWCC_EXTMAP_STR);
if (ext_id > 0) {
fpad->has_twcc = TRUE;
funnel->twcc_pads++;
gst_rtp_funnel_set_twcc_ext_id (funnel, ext_id);
}
forward = FALSE;
break;
}
default:
break;
}
if (forward) {
ret = gst_pad_event_default (pad, parent, event);
} else {
gst_event_unref (event);
}
return ret;
}
static gboolean
gst_rtp_funnel_sink_query (GstPad * pad, GstObject * parent, GstQuery * query)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (parent);
gboolean res = TRUE;
switch (GST_QUERY_TYPE (query)) {
case GST_QUERY_CAPS:
{
GstCaps *filter_caps;
GstCaps *new_caps;
gst_query_parse_caps (query, &filter_caps);
GST_OBJECT_LOCK (funnel);
if (filter_caps) {
new_caps = gst_caps_intersect_full (funnel->srccaps, filter_caps,
GST_CAPS_INTERSECT_FIRST);
} else {
new_caps = gst_caps_copy (funnel->srccaps);
}
GST_OBJECT_UNLOCK (funnel);
if (funnel->common_ts_offset >= 0)
gst_caps_set_simple (new_caps, "timestamp-offset", G_TYPE_UINT,
(guint) funnel->common_ts_offset, NULL);
gst_query_set_caps_result (query, new_caps);
GST_DEBUG_OBJECT (pad, "Answering caps-query with caps: %"
GST_PTR_FORMAT, new_caps);
gst_caps_unref (new_caps);
break;
}
case GST_QUERY_ACCEPT_CAPS:
{
GstCaps *caps;
gboolean result;
gst_query_parse_accept_caps (query, &caps);
GST_OBJECT_LOCK (funnel);
result = gst_caps_is_subset (caps, funnel->srccaps);
if (!result) {
GST_ERROR_OBJECT (pad,
"caps: %" GST_PTR_FORMAT " were not compatible with: %"
GST_PTR_FORMAT, caps, funnel->srccaps);
}
GST_OBJECT_UNLOCK (funnel);
gst_query_set_accept_caps_result (query, result);
break;
}
default:
res = gst_pad_query_default (pad, parent, query);
break;
}
return res;
}
static gboolean
gst_rtp_funnel_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (parent);
gboolean handled = FALSE;
gboolean ret = TRUE;
GST_DEBUG_OBJECT (pad, "received event %" GST_PTR_FORMAT, event);
if (GST_EVENT_TYPE (event) == GST_EVENT_CUSTOM_UPSTREAM) {
const GstStructure *s = gst_event_get_structure (event);
GstPad *fpad;
guint ssrc;
if (s && gst_structure_get_uint (s, "ssrc", &ssrc)) {
handled = TRUE;
GST_OBJECT_LOCK (funnel);
fpad = g_hash_table_lookup (funnel->ssrc_to_pad, GUINT_TO_POINTER (ssrc));
if (fpad)
gst_object_ref (fpad);
GST_OBJECT_UNLOCK (funnel);
if (fpad) {
GST_INFO_OBJECT (pad, "Sending %" GST_PTR_FORMAT " to %" GST_PTR_FORMAT,
event, fpad);
ret = gst_pad_push_event (fpad, event);
gst_object_unref (fpad);
} else {
gst_event_unref (event);
}
}
}
if (!handled) {
gst_pad_event_default (pad, parent, event);
}
return ret;
}
static GstPad *
gst_rtp_funnel_request_new_pad (GstElement * element, GstPadTemplate * templ,
const gchar * name, const GstCaps * caps)
{
GstPad *sinkpad;
(void) caps;
GST_DEBUG_OBJECT (element, "requesting pad");
sinkpad = GST_PAD_CAST (g_object_new (GST_TYPE_RTP_FUNNEL_PAD,
"name", name, "direction", templ->direction, "template", templ,
NULL));
gst_pad_set_chain_function (sinkpad,
GST_DEBUG_FUNCPTR (gst_rtp_funnel_sink_chain));
gst_pad_set_chain_list_function (sinkpad,
GST_DEBUG_FUNCPTR (gst_rtp_funnel_sink_chain_list));
gst_pad_set_event_function (sinkpad,
GST_DEBUG_FUNCPTR (gst_rtp_funnel_sink_event));
gst_pad_set_query_function (sinkpad,
GST_DEBUG_FUNCPTR (gst_rtp_funnel_sink_query));
GST_OBJECT_FLAG_SET (sinkpad, GST_PAD_FLAG_PROXY_CAPS);
GST_OBJECT_FLAG_SET (sinkpad, GST_PAD_FLAG_PROXY_ALLOCATION);
gst_pad_set_active (sinkpad, TRUE);
gst_element_add_pad (element, sinkpad);
GST_DEBUG_OBJECT (element, "requested pad %s:%s",
GST_DEBUG_PAD_NAME (sinkpad));
return sinkpad;
}
static void
gst_rtp_funnel_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (object);
switch (prop_id) {
case PROP_COMMON_TS_OFFSET:
funnel->common_ts_offset = g_value_get_int (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rtp_funnel_get_property (GObject * object, guint prop_id, GValue * value,
GParamSpec * pspec)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (object);
switch (prop_id) {
case PROP_COMMON_TS_OFFSET:
g_value_set_int (value, funnel->common_ts_offset);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static GstStateChangeReturn
gst_rtp_funnel_change_state (GstElement * element, GstStateChange transition)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (element);
GstStateChangeReturn ret;
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
switch (transition) {
case GST_STATE_CHANGE_PAUSED_TO_READY:
funnel->send_sticky_events = TRUE;
break;
default:
break;
}
return ret;
}
static gboolean
_remove_pad_func (gpointer key, gpointer value, gpointer user_data)
{
(void) key;
if (GST_PAD_CAST (value) == GST_PAD_CAST (user_data))
return TRUE;
return FALSE;
}
static void
gst_rtp_funnel_release_pad (GstElement * element, GstPad * pad)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (element);
GST_DEBUG_OBJECT (funnel, "releasing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
g_hash_table_foreach_remove (funnel->ssrc_to_pad, _remove_pad_func, pad);
gst_pad_set_active (pad, FALSE);
gst_element_remove_pad (GST_ELEMENT_CAST (funnel), pad);
}
static void
gst_rtp_funnel_finalize (GObject * object)
{
GstRtpFunnel *funnel = GST_RTP_FUNNEL_CAST (object);
gst_caps_unref (funnel->srccaps);
g_hash_table_destroy (funnel->ssrc_to_pad);
G_OBJECT_CLASS (parent_class)->finalize (object);
}
static void
gst_rtp_funnel_class_init (GstRtpFunnelClass * klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_rtp_funnel_finalize);
gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_rtp_funnel_get_property);
gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_rtp_funnel_set_property);
gstelement_class->request_new_pad =
GST_DEBUG_FUNCPTR (gst_rtp_funnel_request_new_pad);
gstelement_class->release_pad =
GST_DEBUG_FUNCPTR (gst_rtp_funnel_release_pad);
gstelement_class->change_state =
GST_DEBUG_FUNCPTR (gst_rtp_funnel_change_state);
gst_element_class_set_static_metadata (gstelement_class, "RTP funnel",
"RTP Funneling",
"Funnel RTP buffers together for multiplexing",
"Havard Graff <havard@gstip.com>");
gst_element_class_add_static_pad_template (gstelement_class, &sink_template);
gst_element_class_add_static_pad_template (gstelement_class, &src_template);
g_object_class_install_property (gobject_class, PROP_COMMON_TS_OFFSET,
g_param_spec_int ("common-ts-offset", "Common Timestamp Offset",
"Use the same RTP timestamp offset for all sinkpads (-1 = disable)",
-1, G_MAXINT32, DEFAULT_COMMON_TS_OFFSET,
G_PARAM_CONSTRUCT | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
GST_DEBUG_CATEGORY_INIT (gst_rtp_funnel_debug,
"gstrtpfunnel", 0, "funnel element");
}
static void
gst_rtp_funnel_init (GstRtpFunnel * funnel)
{
funnel->srcpad = gst_pad_new_from_static_template (&src_template, "src");
gst_pad_use_fixed_caps (funnel->srcpad);
gst_pad_set_event_function (funnel->srcpad,
GST_DEBUG_FUNCPTR (gst_rtp_funnel_src_event));
gst_element_add_pad (GST_ELEMENT (funnel), funnel->srcpad);
funnel->send_sticky_events = TRUE;
funnel->srccaps = gst_caps_new_empty_simple (RTP_CAPS);
funnel->ssrc_to_pad = g_hash_table_new (NULL, NULL);
funnel->current_pad = NULL;
}