gstreamer/gst/rist/gstristrtpext.c

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/* GStreamer RIST plugin
* Copyright (C) 2019 Net Insight AB
* Author: Olivier Crete <olivier.crete@collabora.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-ristrtpext
* @title: ristrtpext
* @see_also: ristsink
*
* This elements adds the RTP header extension defined by the RIST profile.
*
* If the GstRistRtpExt::drop-null-ts-packets property is set, then it
* will try to parse a MPEG Transport Stream inside the RTP packets
* and look for "null" packets among the first 7 TS packets and remove
* them, and mark their removal in the header.
*
* If the GstRistRtpExt::sequence-number-extension property is set, it will add
* a RTP sequence number roll-over counter to the RTP header extension. This
* code assumes that packets inserted to this element are never more than half
* of the sequence number space (2^15) away from the latest. Re-transmissions
* should therefore be done after processing with this element.
*
* If the GstRistRtpExt::drop-null-ts-packets and
* GstRistRtpExt::sequence-number-extension properties are both FALSE, it is
* pass through.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/rtp/rtp.h>
#include "gstrist.h"
GST_DEBUG_CATEGORY_STATIC (gst_rist_rtp_ext_debug);
#define GST_CAT_DEFAULT gst_rist_rtp_ext_debug
enum
{
PROP_DROP_NULL_TS_PACKETS = 1,
PROP_SEQUENCE_NUMBER_EXTENSION
};
static GstStaticPadTemplate src_templ = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-rtp"));
static GstStaticPadTemplate sink_templ = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-rtp"));
struct _GstRistRtpExt
{
GstElement parent;
GstPad *srcpad, *sinkpad;
gboolean drop_null;
gboolean add_seqnumext;
guint32 extseqnum;
};
G_DEFINE_TYPE_WITH_CODE (GstRistRtpExt, gst_rist_rtp_ext, GST_TYPE_ELEMENT,
GST_DEBUG_CATEGORY_INIT (gst_rist_rtp_ext_debug, "ristrtpext", 0,
"RIST RTP Extension"));
GST_ELEMENT_REGISTER_DEFINE (ristrtpext, "ristrtpext", GST_RANK_NONE,
GST_TYPE_RIST_RTP_EXT);
static GstFlowReturn
gst_rist_rtp_ext_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
{
GstRistRtpExt *self = GST_RIST_RTP_EXT (parent);
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
gboolean drop_null = self->drop_null;
gboolean ts_packet_size = 0;
guint ts_packet_count = 0;
guint8 npd_bits = 0;
gboolean num_packets_deleted = 0;
guint8 *data;
guint wordlen;
if (!self->drop_null && !self->add_seqnumext)
return gst_pad_push (self->srcpad, buffer);
if (self->drop_null) {
if (!gst_rtp_buffer_map (buffer, GST_MAP_READ, &rtp)) {
GST_ELEMENT_ERROR (self, STREAM, MUX, (NULL),
("Could not map RTP buffer"));
goto mapping_error;
}
if (gst_rtp_buffer_get_payload_type (&rtp) == GST_RTP_PAYLOAD_MP2T) {
if (gst_rtp_buffer_get_payload_len (&rtp) % 188 == 0) {
ts_packet_size = 188;
ts_packet_count = gst_rtp_buffer_get_payload_len (&rtp) / 188;
} else if (gst_rtp_buffer_get_payload_len (&rtp) % 204 == 0) {
ts_packet_size = 204;
ts_packet_count = gst_rtp_buffer_get_payload_len (&rtp) / 204;
} else {
drop_null = FALSE;
}
}
gst_rtp_buffer_unmap (&rtp);
}
buffer = gst_buffer_make_writable (buffer);
if (!gst_rtp_buffer_map (buffer, GST_MAP_READWRITE, &rtp)) {
GST_ELEMENT_ERROR (self, STREAM, MUX, (NULL), ("Could not map RTP buffer"));
goto mapping_error;
}
if (drop_null) {
guint8 *data = gst_rtp_buffer_get_payload (&rtp);
guint plen = gst_rtp_buffer_get_payload_len (&rtp);
guint i;
if (gst_rtp_buffer_get_padding (&rtp)) {
GST_ELEMENT_ERROR (self, STREAM, MUX, (NULL),
("FIXME: Can not remove null TS packets if RTP padding is present"));
goto mapping_error;
}
for (i = 0; i < MIN (ts_packet_count, 7); i++) {
guint offset = (i - num_packets_deleted) * ts_packet_size;
guint16 pid;
/* Look for sync byte (0x47) at the start of TS packets */
if (data[offset] != 0x47) {
GST_ELEMENT_ERROR (self, STREAM, MUX, (NULL),
("Buffer does not contain valid MP2T data,"
" the sync byte is not present"));
goto error_mapped;
}
pid = ((data[offset + 1] & 0x1F) << 8) | data[offset + 2];
/* is NULL packet (PID == 0x1FFF means null) */
if (pid == 0x1FFF) {
guint remaining_plen = plen - (num_packets_deleted * ts_packet_size);
num_packets_deleted++;
npd_bits |= 1 << (6 - i);
if (offset + ts_packet_size < remaining_plen)
memmove (data + offset, data + offset + ts_packet_size,
remaining_plen - offset - ts_packet_size);
}
}
}
if (gst_rtp_buffer_get_extension (&rtp)) {
GST_ELEMENT_ERROR (self, STREAM, MUX, (NULL),
("RTP buffer already has an extension set"));
goto error_mapped;
}
gst_rtp_buffer_set_extension (&rtp, TRUE);
gst_rtp_buffer_set_extension_data (&rtp, 'R' << 8 | 'I', 1);
gst_rtp_buffer_get_extension_data (&rtp, NULL, (void **) &data, &wordlen);
data[0] = drop_null << 7;
data[0] |= self->add_seqnumext << 6;
if (ts_packet_count <= 7)
data[0] |= (ts_packet_count & 7) << 3; /* Size */
data[1] = (ts_packet_size == 204) << 7;
data[1] |= (npd_bits & 0x7F);
if (self->add_seqnumext) {
guint16 seqnum = gst_rtp_buffer_get_seq (&rtp);
guint32 extseqnum;
if (GST_BUFFER_IS_DISCONT (buffer))
self->extseqnum = -1;
extseqnum = gst_rist_rtp_ext_seq (&self->extseqnum, seqnum);
GST_WRITE_UINT16_BE (data + 2, (extseqnum >> 16));
}
gst_rtp_buffer_unmap (&rtp);
if (num_packets_deleted != 0)
gst_buffer_resize (buffer, 0,
gst_buffer_get_size (buffer) - (ts_packet_size * num_packets_deleted));
return gst_pad_push (self->srcpad, buffer);
mapping_error:
gst_buffer_unref (buffer);
return GST_FLOW_ERROR;
error_mapped:
gst_rtp_buffer_unmap (&rtp);
gst_buffer_unref (buffer);
return GST_FLOW_ERROR;
}
static void
gst_rist_rtp_ext_init (GstRistRtpExt * self)
{
self->extseqnum = -1;
self->sinkpad = gst_pad_new_from_static_template (&sink_templ,
sink_templ.name_template);
self->srcpad = gst_pad_new_from_static_template (&src_templ,
src_templ.name_template);
GST_PAD_SET_PROXY_ALLOCATION (self->sinkpad);
GST_PAD_SET_PROXY_CAPS (self->sinkpad);
gst_pad_set_chain_function (self->sinkpad, gst_rist_rtp_ext_chain);
gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);
gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
}
static void
gst_rist_rtp_ext_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec)
{
GstRistRtpExt *self = GST_RIST_RTP_EXT (object);
switch (prop_id) {
case PROP_DROP_NULL_TS_PACKETS:
g_value_set_boolean (value, self->drop_null);
break;
case PROP_SEQUENCE_NUMBER_EXTENSION:
g_value_set_boolean (value, self->add_seqnumext);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rist_rtp_ext_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstRistRtpExt *self = GST_RIST_RTP_EXT (object);
switch (prop_id) {
case PROP_DROP_NULL_TS_PACKETS:
self->drop_null = g_value_get_boolean (value);
break;
case PROP_SEQUENCE_NUMBER_EXTENSION:
self->add_seqnumext = g_value_get_boolean (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rist_rtp_ext_class_init (GstRistRtpExtClass * klass)
{
GstElementClass *element_class = (GstElementClass *) klass;
GObjectClass *object_class = (GObjectClass *) klass;
gst_element_class_set_metadata (element_class,
"RIST RTP Extension adder", "Filter/Network",
"Adds RIST TR-06-2 RTP Header extension",
"Olivier Crete <olivier.crete@collabora.com");
gst_element_class_add_static_pad_template (element_class, &src_templ);
gst_element_class_add_static_pad_template (element_class, &sink_templ);
object_class->get_property = gst_rist_rtp_ext_get_property;
object_class->set_property = gst_rist_rtp_ext_set_property;
g_object_class_install_property (object_class, PROP_DROP_NULL_TS_PACKETS,
g_param_spec_boolean ("drop-null-ts-packets", "Drop null TS packets",
"Drop null MPEG-TS packet and replace them with a custom header"
" extension.", FALSE,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | G_PARAM_CONSTRUCT));
g_object_class_install_property (object_class, PROP_SEQUENCE_NUMBER_EXTENSION,
g_param_spec_boolean ("sequence-number-extension",
"Sequence Number Extension",
"Add sequence number extension to packets.", FALSE,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | G_PARAM_CONSTRUCT));
}