gstreamer/subprojects/gst-plugins-good/gst/rtp/gstrtpredenc.c

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/* GStreamer plugin for forward error correction
* Copyright (C) 2017 Pexip
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Author: Mikhail Fludkov <misha@pexip.com>
*/
/**
* SECTION:element-rtpredenc
* @short_description: RTP Redundant Audio Data (RED) encoder
* @title: rtpredenc
*
* Encode Redundant Audio Data (RED) as per RFC 2198.
*
* This element is mostly provided for chrome webrtc compatibility:
* chrome expects protection packets generated by #GstRtpUlpFecEnc
* to be wrapped in RED packets for backward compatibility purposes,
* but does not actually make use of the redundant packets that could
* be encoded with this element.
*
* As such, when used for that purpose, only the #GstRtpRedEnc:pt property
* should be set to a payload type different from both the protected and
* protection packets' payload types.
*
* When using #GstRtpBin, this element should be inserted through the
* #GstRtpBin::request-fec-encoder signal.
*
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* ## Example pipeline
*
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* |[
* gst-launch-1.0 videotestsrc ! x264enc ! video/x-h264, profile=baseline ! rtph264pay pt=96 ! rtpulpfecenc percentage=100 pt=122 ! rtpredenc pt=122 distance=2 ! identity drop-probability=0.05 ! udpsink port=8888
* ]| This example will send a stream with RED and ULP FEC.
*
* See also: #GstRtpRedDec, #GstWebRTCBin, #GstRtpBin
* Since: 1.14
*/
#include <gst/rtp/gstrtpbuffer.h>
#include <string.h>
#include <stdio.h>
#include "gstrtpelements.h"
#include "rtpredcommon.h"
#include "gstrtpredenc.h"
typedef struct
{
guint8 pt;
guint32 timestamp;
GstBuffer *payload;
} RTPHistItem;
static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-rtp"));
static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-rtp"));
#define DEFAULT_PT (0)
#define DEFAULT_DISTANCE (0)
#define DEFAULT_ALLOW_NO_RED_BLOCKS (TRUE)
GST_DEBUG_CATEGORY_STATIC (gst_rtp_red_enc_debug);
#define GST_CAT_DEFAULT (gst_rtp_red_enc_debug)
G_DEFINE_TYPE (GstRtpRedEnc, gst_rtp_red_enc, GST_TYPE_ELEMENT);
GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (rtpredenc, "rtpredenc", GST_RANK_NONE,
GST_TYPE_RTP_RED_ENC, rtp_element_init (plugin));
enum
{
PROP_0,
PROP_PT,
PROP_SENT,
PROP_DISTANCE,
PROP_ALLOW_NO_RED_BLOCKS
};
static void
rtp_hist_item_init (RTPHistItem * item, GstRTPBuffer * rtp,
GstBuffer * rtp_payload)
{
item->pt = gst_rtp_buffer_get_payload_type (rtp);
item->timestamp = gst_rtp_buffer_get_timestamp (rtp);
item->payload = rtp_payload;
}
static RTPHistItem *
rtp_hist_item_new (GstRTPBuffer * rtp, GstBuffer * rtp_payload)
{
RTPHistItem *item = g_slice_new0 (RTPHistItem);
rtp_hist_item_init (item, rtp, rtp_payload);
return item;
}
static void
rtp_hist_item_replace (RTPHistItem * item, GstRTPBuffer * rtp,
GstBuffer * rtp_payload)
{
gst_buffer_unref (item->payload);
rtp_hist_item_init (item, rtp, rtp_payload);
}
static void
rtp_hist_item_free (gpointer _item)
{
RTPHistItem *item = _item;
gst_buffer_unref (item->payload);
g_slice_free (RTPHistItem, item);
}
static GstEvent *
_create_caps_event (const GstCaps * caps, guint8 pt)
{
GstEvent *ret;
GstCaps *new = gst_caps_copy (caps);
GstStructure *s = gst_caps_get_structure (new, 0);
gst_structure_set (s, "payload", G_TYPE_INT, pt, NULL);
GST_INFO ("sinkcaps %" GST_PTR_FORMAT ", srccaps %" GST_PTR_FORMAT,
caps, new);
ret = gst_event_new_caps (new);
gst_caps_unref (new);
return ret;
}
static GstBuffer *
_alloc_red_packet_and_fill_headers (GstRtpRedEnc * self,
RTPHistItem * redundant_block, GstRTPBuffer * inp_rtp)
{
guint red_header_size = rtp_red_block_header_get_length (FALSE) +
(redundant_block ? rtp_red_block_header_get_length (TRUE) : 0);
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guint32 timestamp = gst_rtp_buffer_get_timestamp (inp_rtp);
guint csrc_count = gst_rtp_buffer_get_csrc_count (inp_rtp);
GstBuffer *red = gst_rtp_buffer_new_allocate (red_header_size, 0, csrc_count);
guint8 *red_block_header;
GstRTPBuffer red_rtp = GST_RTP_BUFFER_INIT;
guint i;
if (!gst_rtp_buffer_map (red, GST_MAP_WRITE, &red_rtp))
g_assert_not_reached ();
/* Copying RTP header of incoming packet */
if (gst_rtp_buffer_get_extension (inp_rtp))
GST_WARNING_OBJECT (self, "FIXME: Ignoring RTP extension");
gst_rtp_buffer_set_marker (&red_rtp, gst_rtp_buffer_get_marker (inp_rtp));
gst_rtp_buffer_set_payload_type (&red_rtp, self->pt);
gst_rtp_buffer_set_seq (&red_rtp, gst_rtp_buffer_get_seq (inp_rtp));
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gst_rtp_buffer_set_timestamp (&red_rtp, timestamp);
gst_rtp_buffer_set_ssrc (&red_rtp, gst_rtp_buffer_get_ssrc (inp_rtp));
for (i = 0; i != csrc_count; ++i)
gst_rtp_buffer_set_csrc (&red_rtp, i,
gst_rtp_buffer_get_csrc ((inp_rtp), i));
/* Filling RED block headers */
red_block_header = gst_rtp_buffer_get_payload (&red_rtp);
if (redundant_block) {
rtp_red_block_set_is_redundant (red_block_header, TRUE);
rtp_red_block_set_payload_type (red_block_header, redundant_block->pt);
rtp_red_block_set_timestamp_offset (red_block_header,
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timestamp - redundant_block->timestamp);
rtp_red_block_set_payload_length (red_block_header,
gst_buffer_get_size (redundant_block->payload));
red_block_header += rtp_red_block_header_get_length (TRUE);
}
rtp_red_block_set_is_redundant (red_block_header, FALSE);
rtp_red_block_set_payload_type (red_block_header,
gst_rtp_buffer_get_payload_type (inp_rtp));
/* FIXME: remove that logic once https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/923
* has been addressed. */
if (self->twcc_ext_id != 0) {
guint8 appbits;
gpointer inp_data;
guint inp_size;
guint16 data;
/* If the input buffer was meant to hold a TWCC seqnum, we also do that
* for our wrapper */
if (gst_rtp_buffer_get_extension_onebyte_header (inp_rtp, self->twcc_ext_id,
0, &inp_data, &inp_size)) {
gst_rtp_buffer_add_extension_onebyte_header (&red_rtp, 1, &data,
sizeof (guint16));
} else if (gst_rtp_buffer_get_extension_twobytes_header (inp_rtp, &appbits,
self->twcc_ext_id, 0, &inp_data, &inp_size)) {
gst_rtp_buffer_add_extension_twobytes_header (&red_rtp, appbits,
self->twcc_ext_id, &data, sizeof (guint16));
}
}
gst_rtp_buffer_unmap (&red_rtp);
gst_buffer_copy_into (red, inp_rtp->buffer, GST_BUFFER_COPY_METADATA, 0, -1);
return red;
}
static GstBuffer *
_create_red_packet (GstRtpRedEnc * self,
GstRTPBuffer * rtp, RTPHistItem * redundant_block, GstBuffer * main_block)
{
GstBuffer *red =
_alloc_red_packet_and_fill_headers (self, redundant_block, rtp);
if (redundant_block)
red = gst_buffer_append (red, gst_buffer_ref (redundant_block->payload));
red = gst_buffer_append (red, gst_buffer_ref (main_block));
return red;
}
static RTPHistItem *
_red_history_get_redundant_block (GstRtpRedEnc * self,
guint32 current_timestamp, guint distance)
{
RTPHistItem *item;
gint32 timestamp_offset;
if (0 == distance || 0 == self->rtp_history->length)
return NULL;
item = self->rtp_history->tail->data;
timestamp_offset = current_timestamp - item->timestamp;
if (G_UNLIKELY (timestamp_offset > RED_BLOCK_TIMESTAMP_OFFSET_MAX)) {
GST_WARNING_OBJECT (self,
"Can't create redundant block with distance %u, "
"timestamp offset is too large %d (%u - %u) > %u",
distance, timestamp_offset, current_timestamp, item->timestamp,
RED_BLOCK_TIMESTAMP_OFFSET_MAX);
return NULL;
}
if (G_UNLIKELY (timestamp_offset < 0)) {
GST_WARNING_OBJECT (self,
"Can't create redundant block with distance %u, "
"timestamp offset is negative %d (%u - %u)",
distance, timestamp_offset, current_timestamp, item->timestamp);
return NULL;
}
if (G_UNLIKELY (gst_buffer_get_size (item->payload) > RED_BLOCK_LENGTH_MAX)) {
GST_WARNING_OBJECT (self,
"Can't create redundant block with distance %u, "
"red block is too large %u > %u",
distance, (guint) gst_buffer_get_size (item->payload),
RED_BLOCK_LENGTH_MAX);
return NULL;
}
/* _red_history_trim should take care it never happens */
g_assert_cmpint (self->rtp_history->length, <=, distance);
if (G_UNLIKELY (self->rtp_history->length < distance))
GST_DEBUG_OBJECT (self,
"Don't have enough buffers yet, "
"adding redundant block with distance %u and timestamp %u",
self->rtp_history->length, item->timestamp);
return item;
}
static void
_red_history_prepend (GstRtpRedEnc * self,
GstRTPBuffer * rtp, GstBuffer * rtp_payload, guint max_history_length)
{
GList *link;
if (0 == max_history_length) {
if (rtp_payload)
gst_buffer_unref (rtp_payload);
return;
}
g_assert (NULL != rtp_payload);
if (self->rtp_history->length >= max_history_length) {
link = g_queue_pop_tail_link (self->rtp_history);
rtp_hist_item_replace (link->data, rtp, rtp_payload);
} else {
link = g_list_alloc ();
link->data = rtp_hist_item_new (rtp, rtp_payload);
}
g_queue_push_head_link (self->rtp_history, link);
}
static void
_red_history_trim (GstRtpRedEnc * self, guint max_history_length)
{
while (max_history_length < self->rtp_history->length)
rtp_hist_item_free (g_queue_pop_tail (self->rtp_history));
}
static GstFlowReturn
_pad_push (GstRtpRedEnc * self, GstBuffer * buffer, gboolean is_red)
{
if (self->send_caps || is_red != self->is_current_caps_red) {
GstEvent *event;
GstCaps *caps = gst_pad_get_current_caps (self->sinkpad);
if (is_red)
event = _create_caps_event (caps, self->pt);
else
event = gst_event_new_caps (caps);
gst_caps_unref (caps);
gst_pad_push_event (self->srcpad, event);
self->send_caps = FALSE;
self->is_current_caps_red = is_red;
}
return gst_pad_push (self->srcpad, buffer);
}
static GstFlowReturn
_push_nonred_packet (GstRtpRedEnc * self,
GstRTPBuffer * rtp, GstBuffer * buffer, guint distance)
{
GstBuffer *main_block = distance > 0 ?
gst_rtp_buffer_get_payload_buffer (rtp) : NULL;
_red_history_prepend (self, rtp, main_block, distance);
gst_rtp_buffer_unmap (rtp);
return _pad_push (self, buffer, FALSE);
}
static GstFlowReturn
_push_red_packet (GstRtpRedEnc * self,
GstRTPBuffer * rtp, GstBuffer * buffer, RTPHistItem * redundant_block,
guint distance)
{
GstBuffer *main_block = gst_rtp_buffer_get_payload_buffer (rtp);
GstBuffer *red_buffer =
_create_red_packet (self, rtp, redundant_block, main_block);
_red_history_prepend (self, rtp, main_block, distance);
gst_rtp_buffer_unmap (rtp);
gst_buffer_unref (buffer);
self->num_sent++;
return _pad_push (self, red_buffer, TRUE);
}
static GstFlowReturn
gst_rtp_red_enc_chain (GstPad G_GNUC_UNUSED * pad, GstObject * parent,
GstBuffer * buffer)
{
GstRtpRedEnc *self = GST_RTP_RED_ENC (parent);
guint distance = self->distance;
guint only_with_redundant_data = !self->allow_no_red_blocks;
RTPHistItem *redundant_block;
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
/* We need to "trim" the history if 'distance' property has changed */
_red_history_trim (self, distance);
if (0 == distance && only_with_redundant_data)
return _pad_push (self, buffer, FALSE);
if (!gst_rtp_buffer_map (buffer, GST_MAP_READ, &rtp))
return _pad_push (self, buffer, self->is_current_caps_red);
/* If can't get data for redundant block push the packet as is */
redundant_block = _red_history_get_redundant_block (self,
gst_rtp_buffer_get_timestamp (&rtp), distance);
if (NULL == redundant_block && only_with_redundant_data)
return _push_nonred_packet (self, &rtp, buffer, distance);
/* About to create RED packet with or without redundant data */
return _push_red_packet (self, &rtp, buffer, redundant_block, distance);
}
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;
}
#define TWCC_EXTMAP_STR "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01"
static gboolean
gst_rtp_red_enc_event_sink (GstPad * pad, GstObject * parent, GstEvent * event)
{
GstRtpRedEnc *self = GST_RTP_RED_ENC (parent);
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_CAPS:
{
GstCaps *caps;
GstStructure *s;
gboolean replace_with_red_caps =
self->is_current_caps_red || self->allow_no_red_blocks;
gst_event_parse_caps (event, &caps);
s = gst_caps_get_structure (caps, 0);
self->twcc_ext_id = _get_extmap_id_for_attribute (s, TWCC_EXTMAP_STR);
GST_INFO_OBJECT (self, "TWCC extension ID: %u", self->twcc_ext_id);
if (replace_with_red_caps) {
gst_event_take (&event, _create_caps_event (caps, self->pt));
self->is_current_caps_red = TRUE;
}
break;
}
default:
break;
}
return gst_pad_event_default (pad, parent, event);
}
static void
gst_rtp_red_enc_dispose (GObject * obj)
{
GstRtpRedEnc *self = GST_RTP_RED_ENC (obj);
g_queue_free_full (self->rtp_history, rtp_hist_item_free);
G_OBJECT_CLASS (gst_rtp_red_enc_parent_class)->dispose (obj);
}
static void
gst_rtp_red_enc_init (GstRtpRedEnc * self)
{
GstPadTemplate *pad_template;
pad_template =
gst_element_class_get_pad_template (GST_ELEMENT_GET_CLASS (self), "src");
self->srcpad = gst_pad_new_from_template (pad_template, "src");
gst_element_add_pad (GST_ELEMENT_CAST (self), self->srcpad);
pad_template =
gst_element_class_get_pad_template (GST_ELEMENT_GET_CLASS (self), "sink");
self->sinkpad = gst_pad_new_from_template (pad_template, "sink");
gst_pad_set_chain_function (self->sinkpad,
GST_DEBUG_FUNCPTR (gst_rtp_red_enc_chain));
gst_pad_set_event_function (self->sinkpad,
GST_DEBUG_FUNCPTR (gst_rtp_red_enc_event_sink));
GST_PAD_SET_PROXY_CAPS (self->sinkpad);
GST_PAD_SET_PROXY_ALLOCATION (self->sinkpad);
gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);
self->pt = DEFAULT_PT;
self->distance = DEFAULT_DISTANCE;
self->allow_no_red_blocks = DEFAULT_ALLOW_NO_RED_BLOCKS;
self->num_sent = 0;
self->rtp_history = g_queue_new ();
}
static void
gst_rtp_red_enc_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstRtpRedEnc *self = GST_RTP_RED_ENC (object);
switch (prop_id) {
case PROP_PT:
{
gint prev_pt = self->pt;
self->pt = g_value_get_int (value);
self->send_caps = self->pt != prev_pt && self->is_current_caps_red;
}
break;
case PROP_DISTANCE:
self->distance = g_value_get_uint (value);
break;
case PROP_ALLOW_NO_RED_BLOCKS:
self->allow_no_red_blocks = g_value_get_boolean (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rtp_red_enc_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec)
{
GstRtpRedEnc *self = GST_RTP_RED_ENC (object);
switch (prop_id) {
case PROP_PT:
g_value_set_int (value, self->pt);
break;
case PROP_SENT:
g_value_set_uint (value, self->num_sent);
break;
case PROP_DISTANCE:
g_value_set_uint (value, self->distance);
break;
case PROP_ALLOW_NO_RED_BLOCKS:
g_value_set_boolean (value, self->allow_no_red_blocks);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rtp_red_enc_class_init (GstRtpRedEncClass * klass)
{
GObjectClass *gobject_class;
GstElementClass *element_class;
gobject_class = G_OBJECT_CLASS (klass);
element_class = GST_ELEMENT_CLASS (klass);
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&src_template));
gst_element_class_add_pad_template (element_class,
gst_static_pad_template_get (&sink_template));
gst_element_class_set_metadata (element_class,
"Redundant Audio Data (RED) Encoder",
"Codec/Payloader/Network/RTP",
"Encode Redundant Audio Data (RED)",
"Hani Mustafa <hani@pexip.com>, Mikhail Fludkov <misha@pexip.com>");
gobject_class->set_property =
GST_DEBUG_FUNCPTR (gst_rtp_red_enc_set_property);
gobject_class->get_property =
GST_DEBUG_FUNCPTR (gst_rtp_red_enc_get_property);
gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_rtp_red_enc_dispose);
g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_PT,
g_param_spec_int ("pt", "payload type",
"Payload type FEC packets (-1 disable)",
0, 127, DEFAULT_PT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_SENT,
g_param_spec_uint ("sent", "Sent",
"Count of sent packets",
0, G_MAXUINT32, 0, G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_DISTANCE,
g_param_spec_uint ("distance", "RED distance",
"Tells which media packet to use as a redundant block "
"(0 - no redundant blocks, 1 to use previous packet, "
"2 to use the packet before previous, etc.)",
0, G_MAXUINT32, DEFAULT_DISTANCE,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (G_OBJECT_CLASS (klass),
PROP_ALLOW_NO_RED_BLOCKS, g_param_spec_boolean ("allow-no-red-blocks",
"Allow no redundant blocks",
"true - can produce RED packets even without redundant blocks (distance==0) "
"false - RED packets will be produced only if distance>0",
DEFAULT_ALLOW_NO_RED_BLOCKS,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
GST_DEBUG_CATEGORY_INIT (gst_rtp_red_enc_debug, "rtpredenc", 0,
"RTP RED Encoder");
}