gstreamer/gst/rist/gstristrtpdeext.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-ristrtpdeext
* @title: ristrtpdeext
* @see_also: ristsrc
*
* This element removes the RTP header extension. If the RTP header extension
* contained information about remove MPEG Transport Stream null packets, it
* re-inserts them.
*
* If, according to the RTP sequence number and the sequence number
* extension in the RTP header extension, the packet is more than 2^16
* packets before the latest received, it will also drop it because it
* is too old for the jitterbuffer to handle properly.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/rtp/rtp.h>
#include "gstrist.h"
GST_DEBUG_CATEGORY_STATIC (gst_rist_rtp_deext_debug);
#define GST_CAT_DEFAULT gst_rist_rtp_deext_debug
enum
{
PROP_0 = 0,
PROP_MAX_EXT_SEQNUM,
PROP_HAVE_EXT_SEQNUM
};
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 _GstRistRtpDeext
{
GstElement parent;
GstPad *srcpad, *sinkpad;
gboolean have_extseqnum;
guint32 max_extseqnum;
};
G_DEFINE_TYPE_WITH_CODE (GstRistRtpDeext, gst_rist_rtp_deext, GST_TYPE_ELEMENT,
GST_DEBUG_CATEGORY_INIT (gst_rist_rtp_deext_debug, "ristrtpdeext", 0,
"RIST RTP De-extension"));
static guint8
bit_count (guint8 value)
{
guint8 count = 0;
while (value > 0) { /* until all bits are zero */
if ((value & 1) == 1) /* check lower bit */
count++;
value >>= 1; /* shift bits, removing lower bit */
}
return count;
}
static GstFlowReturn
gst_rist_rtp_deext_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
{
GstRistRtpDeext *self = GST_RIST_RTP_DEEXT (parent);
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
GstBuffer *outbuf;
gboolean has_seqnum_ext;
gboolean has_drop_null;
gboolean ts_packet_size;
guint orig_ts_packet_count;
guint16 bits;
guint8 npd_bits;
guint8 num_packets_deleted;
guint extlen;
gpointer extdata = NULL;
guint8 *data = NULL;
guint8 *payload;
guint plen;
guint i;
GstMemory *mem = NULL;
GstMapInfo map;
guint num_restored = 0;
guint orig_payload_offset;
guint hdrlen;
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_extension_data (&rtp, &bits, &extdata, &extlen)) {
/* Has no extension, let's push out without modifying */
gst_rtp_buffer_unmap (&rtp);
return gst_pad_push (self->srcpad, buffer);
}
if (bits != ('R' << 8 | 'I')) {
gst_rtp_buffer_unmap (&rtp);
GST_LOG_OBJECT (self, "Buffer %" GST_PTR_FORMAT
" has an extension that's not the RIST one, ignoring", buffer);
return gst_pad_push (self->srcpad, buffer);
}
if (extlen != 1) {
gst_rtp_buffer_unmap (&rtp);
GST_LOG_OBJECT (self, "Buffer %" GST_PTR_FORMAT
" has a RIST extension that's not of length 1, ignoring", buffer);
return gst_pad_push (self->srcpad, buffer);
}
data = extdata;
has_drop_null = (data[0] >> 7) & 1; /* N */
has_seqnum_ext = (data[0] >> 6) & 1; /* E */
orig_ts_packet_count = (data[0] >> 3) & 7; /* Size */
ts_packet_size = ((data[1] >> 7) & 1) ? 204 : 188;
npd_bits = data[1] & 0x7F;
num_packets_deleted = bit_count (npd_bits);
self->have_extseqnum = has_seqnum_ext;
if (has_seqnum_ext) {
guint16 seqnumext_val = GST_READ_UINT16_BE (data + 2);
guint32 extseqnum = seqnumext_val << 16 | gst_rtp_buffer_get_seq (&rtp);
if (extseqnum < self->max_extseqnum &&
self->max_extseqnum - extseqnum > G_MAXINT16) {
gst_rtp_buffer_unmap (&rtp);
gst_buffer_unref (buffer);
GST_WARNING_OBJECT (self, "Buffer with extended seqnum %u is more than"
" G_MAXINT16 (%u) before the higher received seqnum %u, dropping to"
" avoid confusing downstream elements.",
extseqnum, G_MAXINT16, self->max_extseqnum);
return GST_FLOW_OK;
}
self->max_extseqnum = MAX (self->max_extseqnum, extseqnum);
}
if (!has_drop_null || num_packets_deleted == 0)
goto no_restore;
payload = gst_rtp_buffer_get_payload (&rtp);
plen = gst_rtp_buffer_get_payload_len (&rtp);
if (plen != 0) {
if (plen % 188 == 0) {
if (ts_packet_size != 188) {
GST_WARNING_OBJECT (self, "RTP Header extension says packet size is"
" 204, but payload length is divisible by 188, ignoring header");
ts_packet_size = 188;
}
} else if (plen % 204 == 0) {
if (ts_packet_size != 204) {
GST_WARNING_OBJECT (self, "RTP Header extension says packet size is"
" 188, but payload length is divisible by 204, ignoring header");
ts_packet_size = 204;
}
} else {
GST_WARNING_OBJECT (self, "Payload length (%u) is not divisible by 188"
" or 204, taking TS packet size from header (%u), not restoring"
" null packets", plen, ts_packet_size);
goto no_restore;
}
}
if ((plen / ts_packet_size) + num_packets_deleted != orig_ts_packet_count) {
if (orig_ts_packet_count == 0)
GST_LOG_OBJECT (self, "Original number of packet is 0, using NPD bits to"
" restore packet size to %d",
(plen / ts_packet_size) + num_packets_deleted);
else
GST_WARNING_OBJECT (self, "The number of deleted packets (%u) + the"
" number of transmitted packets (%d) is not equal to the declared"
" original packet count (%d), ignoring it", num_packets_deleted,
(plen / ts_packet_size), orig_ts_packet_count);
orig_ts_packet_count = (plen / ts_packet_size) + num_packets_deleted;
}
GST_LOG_OBJECT (self, "Restoring %u null TS packets for a total"
" of %u packets", num_packets_deleted, orig_ts_packet_count);
mem = gst_allocator_alloc (NULL, orig_ts_packet_count * ts_packet_size, NULL);
gst_memory_map (mem, &map, GST_MAP_READWRITE);
/* Re-create the null packets */
for (i = 0; i < orig_ts_packet_count; i++) {
gboolean was_deleted = (npd_bits & (1 << (6 - i))) != 0;
guint8 *pktdst = map.data + (i * ts_packet_size);
if (was_deleted) {
memset (pktdst, 0, ts_packet_size);
pktdst[0] = 0x47;
pktdst[1] = 0x1F;
pktdst[2] = 0xFF;
pktdst[3] = 0x10;
num_restored++;
} else {
guint src_offset = (i - num_restored) * ts_packet_size;
if (src_offset + ts_packet_size > plen) {
GST_WARNING_OBJECT (self, "Invalid NPD bits (0x%x), not enough data in"
" the original RTP packet, not restoring TS packet %d", npd_bits,
i);
} else {
memcpy (pktdst, payload + src_offset, ts_packet_size);
}
}
}
gst_memory_unmap (mem, &map);
no_restore:
orig_payload_offset = gst_rtp_buffer_get_header_len (&rtp);
hdrlen = orig_payload_offset - (4 + (extlen * 4));
gst_rtp_buffer_unmap (&rtp);
/* Create a new buffer without the header extension */
outbuf = gst_buffer_copy_region (buffer, GST_BUFFER_COPY_ALL, 0, hdrlen);
/* Unset extension flag, can't use the GstRTPBuffer function as they will
* try to look for the extension itself which isn't there if the flag is set.
*/
gst_buffer_map (outbuf, &map, GST_MAP_READWRITE);
map.data[0] &= ~0x10;
gst_buffer_unmap (outbuf, &map);
if (mem)
gst_buffer_append_memory (outbuf, mem);
else
gst_buffer_copy_into (outbuf, buffer, GST_BUFFER_COPY_MEMORY,
orig_payload_offset, -1);
gst_buffer_unref (buffer);
return gst_pad_push (self->srcpad, outbuf);
mapping_error:
gst_buffer_unref (buffer);
return GST_FLOW_ERROR;
}
static void
gst_rist_rtp_deext_init (GstRistRtpDeext * self)
{
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_deext_chain);
gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);
gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
}
static void
gst_rist_rtp_deext_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec)
{
GstRistRtpDeext *self = GST_RIST_RTP_DEEXT (object);
switch (prop_id) {
case PROP_MAX_EXT_SEQNUM:
g_value_set_uint (value, self->max_extseqnum);
break;
case PROP_HAVE_EXT_SEQNUM:
g_value_set_boolean (value, self->have_extseqnum);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_rist_rtp_deext_class_init (GstRistRtpDeextClass * klass)
{
GstElementClass *element_class = (GstElementClass *) klass;
GObjectClass *object_class = (GObjectClass *) klass;
gst_element_class_set_metadata (element_class,
"RIST RTP Extension remover", "Filter/Network",
"Removes 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_deext_get_property;
g_object_class_install_property (object_class, PROP_MAX_EXT_SEQNUM,
g_param_spec_uint ("max-ext-seqnum",
"Maximum Extended Sequence Number",
"Largest extended sequence number received", 0, G_MAXUINT, 0,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (object_class, PROP_HAVE_EXT_SEQNUM,
g_param_spec_boolean ("have-ext-seqnum",
"Have extended seqnum",
"Has an extended sequence number extension been seen", FALSE,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
}