gstreamer/gst/rtp/gstrtpklvdepay.c
2021-03-29 12:45:22 +02:00

393 lines
11 KiB
C

/* GStreamer RTP KLV Depayloader
* Copyright (C) 2014-2015 Tim-Philipp Müller <tim@centricular.com>>
* Copyright (C) 2014-2015 Centricular Ltd
*
* 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-rtpklvdepay
* @title: rtpklvdepay
* @see_also: rtpklvpay
*
* Extract KLV metadata from RTP packets according to RFC 6597.
* For detailed information see: http://tools.ietf.org/html/rfc6597
*
* ## Example pipeline
* |[
* gst-launch-1.0 udpsrc caps='application/x-rtp, media=(string)application, clock-rate=(int)90000, encoding-name=(string)SMPTE336M' ! rtpklvdepay ! fakesink dump=true
* ]| This example pipeline will depayload an RTP KLV stream and display
* a hexdump of the KLV data on stdout.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "gstrtpelements.h"
#include "gstrtpklvdepay.h"
#include <string.h>
GST_DEBUG_CATEGORY_STATIC (klvdepay_debug);
#define GST_CAT_DEFAULT (klvdepay_debug)
static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("meta/x-klv, parsed = (bool) true"));
static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-rtp, "
"media = (string) application, clock-rate = (int) [1, MAX], "
"encoding-name = (string) SMPTE336M")
);
#define gst_rtp_klv_depay_parent_class parent_class
G_DEFINE_TYPE (GstRtpKlvDepay, gst_rtp_klv_depay, GST_TYPE_RTP_BASE_DEPAYLOAD);
GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (rtpklvdepay, "rtpklvdepay",
GST_RANK_SECONDARY, GST_TYPE_RTP_KLV_DEPAY, rtp_element_init (plugin));
static void gst_rtp_klv_depay_finalize (GObject * object);
static GstStateChangeReturn gst_rtp_klv_depay_change_state (GstElement *
element, GstStateChange transition);
static gboolean gst_rtp_klv_depay_setcaps (GstRTPBaseDepayload * depayload,
GstCaps * caps);
static GstBuffer *gst_rtp_klv_depay_process (GstRTPBaseDepayload * depayload,
GstRTPBuffer * rtp);
static gboolean gst_rtp_klv_depay_handle_event (GstRTPBaseDepayload * depay,
GstEvent * ev);
static void gst_rtp_klv_depay_reset (GstRtpKlvDepay * klvdepay);
static void
gst_rtp_klv_depay_class_init (GstRtpKlvDepayClass * klass)
{
GstElementClass *element_class = (GstElementClass *) klass;
GObjectClass *gobject_class = (GObjectClass *) klass;
GstRTPBaseDepayloadClass *rtpbasedepayload_class;
GST_DEBUG_CATEGORY_INIT (klvdepay_debug, "klvdepay", 0,
"RTP KLV Depayloader");
gobject_class->finalize = gst_rtp_klv_depay_finalize;
element_class->change_state = gst_rtp_klv_depay_change_state;
gst_element_class_add_static_pad_template (element_class, &src_template);
gst_element_class_add_static_pad_template (element_class, &sink_template);
gst_element_class_set_static_metadata (element_class,
"RTP KLV Depayloader", "Codec/Depayloader/Network/RTP",
"Extracts KLV (SMPTE ST 336) metadata from RTP packets",
"Tim-Philipp Müller <tim@centricular.com>");
rtpbasedepayload_class = (GstRTPBaseDepayloadClass *) klass;
rtpbasedepayload_class->set_caps = gst_rtp_klv_depay_setcaps;
rtpbasedepayload_class->process_rtp_packet = gst_rtp_klv_depay_process;
rtpbasedepayload_class->handle_event = gst_rtp_klv_depay_handle_event;
}
static void
gst_rtp_klv_depay_init (GstRtpKlvDepay * klvdepay)
{
klvdepay->adapter = gst_adapter_new ();
}
static void
gst_rtp_klv_depay_finalize (GObject * object)
{
GstRtpKlvDepay *klvdepay;
klvdepay = GST_RTP_KLV_DEPAY (object);
gst_rtp_klv_depay_reset (klvdepay);
g_object_unref (klvdepay->adapter);
G_OBJECT_CLASS (parent_class)->finalize (object);
}
static void
gst_rtp_klv_depay_reset (GstRtpKlvDepay * klvdepay)
{
GST_DEBUG_OBJECT (klvdepay, "resetting");
gst_adapter_clear (klvdepay->adapter);
klvdepay->resync = TRUE;
klvdepay->last_rtp_ts = -1;
}
static gboolean
gst_rtp_klv_depay_handle_event (GstRTPBaseDepayload * depay, GstEvent * ev)
{
switch (GST_EVENT_TYPE (ev)) {
case GST_EVENT_STREAM_START:{
GstStreamFlags flags;
ev = gst_event_make_writable (ev);
gst_event_parse_stream_flags (ev, &flags);
gst_event_set_stream_flags (ev, flags | GST_STREAM_FLAG_SPARSE);
break;
}
default:
break;
}
return GST_RTP_BASE_DEPAYLOAD_CLASS (parent_class)->handle_event (depay, ev);
}
static gboolean
gst_rtp_klv_depay_setcaps (GstRTPBaseDepayload * depayload, GstCaps * caps)
{
GstStructure *s;
GstCaps *src_caps;
gboolean res;
gint clock_rate;
s = gst_caps_get_structure (caps, 0);
if (!gst_structure_get_int (s, "clock-rate", &clock_rate))
return FALSE;
depayload->clock_rate = clock_rate;
src_caps = gst_static_pad_template_get_caps (&src_template);
res = gst_pad_set_caps (GST_RTP_BASE_DEPAYLOAD_SRCPAD (depayload), src_caps);
gst_caps_unref (src_caps);
return res;
}
static gboolean
klv_get_vlen (const guint8 * data, guint data_len, guint64 * v_len,
gsize * len_size)
{
guint8 first_byte, len_len;
guint64 len;
g_assert (data_len > 0);
first_byte = *data++;
if ((first_byte & 0x80) == 0) {
*v_len = first_byte & 0x7f;
*len_size = 1;
return TRUE;
}
len_len = first_byte & 0x7f;
if (len_len == 0 || len_len > 8)
return FALSE;
if ((1 + len_len) > data_len)
return FALSE;
*len_size = 1 + len_len;
len = 0;
while (len_len > 0) {
len = len << 8 | *data++;
--len_len;
}
*v_len = len;
return TRUE;
}
static GstBuffer *
gst_rtp_klv_depay_process_data (GstRtpKlvDepay * klvdepay)
{
gsize avail, data_len, len_size;
GstBuffer *outbuf;
guint8 data[1 + 8];
guint64 v_len;
avail = gst_adapter_available (klvdepay->adapter);
GST_TRACE_OBJECT (klvdepay, "%" G_GSIZE_FORMAT " bytes in adapter", avail);
if (avail == 0)
return NULL;
/* need at least 16 bytes of UL key plus 1 byte of length */
if (avail < 16 + 1)
goto bad_klv_packet;
/* check if the declared KLV unit size matches actual bytes available */
data_len = MIN (avail - 16, 1 + 8);
gst_adapter_copy (klvdepay->adapter, data, 16, data_len);
if (!klv_get_vlen (data, data_len, &v_len, &len_size))
goto bad_klv_packet;
GST_LOG_OBJECT (klvdepay, "want %" G_GUINT64_FORMAT " bytes, "
"have %" G_GSIZE_FORMAT " bytes", 16 + len_size + v_len, avail);
if (avail < 16 + len_size + v_len)
goto incomplete_klv_packet;
/* something is wrong, this shouldn't ever happen */
if (avail > 16 + len_size + v_len)
goto bad_klv_packet;
outbuf = gst_adapter_take_buffer (klvdepay->adapter, avail);
/* Mark buffers as key unit to signal this is the start of a KLV unit
* (for now all buffers will be flagged like this, since all buffers are
* self-contained KLV units, but in future that might change) */
outbuf = gst_buffer_make_writable (outbuf);
GST_BUFFER_FLAG_UNSET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
return outbuf;
/* ERRORS */
bad_klv_packet:
{
GST_WARNING_OBJECT (klvdepay, "bad KLV packet, dropping");
gst_rtp_klv_depay_reset (klvdepay);
return NULL;
}
incomplete_klv_packet:
{
GST_DEBUG_OBJECT (klvdepay, "partial KLV packet: have %u bytes, want %u",
(guint) avail, (guint) (16 + len_size + v_len));
return NULL;
}
}
/* We're trying to be pragmatic here, not quite as strict as the spec wants
* us to be with regard to marker bits and resyncing after packet loss */
static GstBuffer *
gst_rtp_klv_depay_process (GstRTPBaseDepayload * depayload, GstRTPBuffer * rtp)
{
GstRtpKlvDepay *klvdepay = GST_RTP_KLV_DEPAY (depayload);
GstBuffer *payload, *outbuf = NULL;
gboolean marker, start = FALSE, maybe_start;
guint32 rtp_ts;
guint16 seq;
guint payload_len;
/* Ignore DISCONT on first buffer and on buffers following a discont */
if (GST_BUFFER_IS_DISCONT (rtp->buffer) && klvdepay->last_rtp_ts != -1) {
GST_WARNING_OBJECT (klvdepay, "DISCONT, need to resync");
gst_rtp_klv_depay_reset (klvdepay);
}
payload_len = gst_rtp_buffer_get_payload_len (rtp);
/* marker bit signals last fragment of a KLV unit */
marker = gst_rtp_buffer_get_marker (rtp);
seq = gst_rtp_buffer_get_seq (rtp);
/* packet directly after one with marker bit set => start */
start = klvdepay->last_marker_seq != -1
&& gst_rtp_buffer_compare_seqnum (klvdepay->last_marker_seq, seq) == 1;
/* deduce start of new KLV unit in case sender doesn't set marker bits
* (it's not like the spec is ambiguous about that, but what can you do) */
rtp_ts = gst_rtp_buffer_get_timestamp (rtp);
maybe_start = klvdepay->last_rtp_ts == -1 || klvdepay->last_rtp_ts != rtp_ts;
klvdepay->last_rtp_ts = rtp_ts;
/* fallback to detect self-contained single KLV unit (usual case) */
if ((!start || !marker || maybe_start) && payload_len > 16) {
const guint8 *data;
guint64 v_len;
gsize len_size;
data = gst_rtp_buffer_get_payload (rtp);
if (GST_READ_UINT32_BE (data) == 0x060e2b34 &&
klv_get_vlen (data + 16, payload_len - 16, &v_len, &len_size)) {
if (16 + len_size + v_len == payload_len) {
GST_LOG_OBJECT (klvdepay, "Looks like a self-contained KLV unit");
marker = TRUE;
start = TRUE;
} else if (16 + len_size + v_len > payload_len) {
GST_LOG_OBJECT (klvdepay,
"Looks like the start of a fragmented KLV unit");
start = TRUE;
}
}
}
/* If this is the first packet and looks like a start, clear resync flag */
if (klvdepay->resync && klvdepay->last_marker_seq == -1 && start)
klvdepay->resync = FALSE;
if (marker)
klvdepay->last_marker_seq = seq;
GST_LOG_OBJECT (klvdepay, "payload of %u bytes, marker=%d, start=%d",
payload_len, marker, start);
if (klvdepay->resync && !start) {
GST_DEBUG_OBJECT (klvdepay, "Dropping buffer, waiting to resync");
if (marker)
klvdepay->resync = FALSE;
goto done;
}
if (start && !marker)
outbuf = gst_rtp_klv_depay_process_data (klvdepay);
payload = gst_rtp_buffer_get_payload_buffer (rtp);
gst_adapter_push (klvdepay->adapter, payload);
if (marker)
outbuf = gst_rtp_klv_depay_process_data (klvdepay);
done:
return outbuf;
}
static GstStateChangeReturn
gst_rtp_klv_depay_change_state (GstElement * element, GstStateChange transition)
{
GstRtpKlvDepay *klvdepay;
GstStateChangeReturn ret;
klvdepay = GST_RTP_KLV_DEPAY (element);
switch (transition) {
case GST_STATE_CHANGE_READY_TO_PAUSED:
gst_rtp_klv_depay_reset (klvdepay);
klvdepay->last_marker_seq = -1;
break;
default:
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
switch (transition) {
case GST_STATE_CHANGE_PAUSED_TO_READY:
gst_rtp_klv_depay_reset (klvdepay);
break;
default:
break;
}
return ret;
}