gstreamer/gst/rtp/gstrtph261depay.c

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/* GStreamer
*
* Copyright (C) <2014> Stian Selnes <stian@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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* SECTION:element-rtph261depay
* @title: rtph261depay
* @see_also: rtph261pay
*
* Extract encoded H.261 video frames from RTP packets according to RFC 4587.
* For detailed information see: https://www.rfc-editor.org/rfc/rfc4587.txt
*
* The depayloader takes an RTP packet and extracts its H.261 stream. It
* aggregates the extracted stream until a complete frame is received before
* it pushes it downstream.
*
* ## Example pipeline
* |[
* gst-launch-1.0 udpsrc caps='application/x-rtp, payload=31' ! rtph261depay ! avdec_h261 ! autovideosink
* ]| This example pipeline will depayload and decode an RTP H.261 video stream.
* Refer to the rtph261pay example to create the RTP stream.
*
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <string.h>
#include <gst/rtp/gstrtpbuffer.h>
#include <gst/video/video.h>
#include "gstrtph261depay.h"
#include "gstrtph261pay.h" /* GstRtpH261PayHeader */
#include "gstrtputils.h"
GST_DEBUG_CATEGORY_STATIC (rtph261depay_debug);
#define GST_CAT_DEFAULT (rtph261depay_debug)
static const guint8 NO_LEFTOVER = 0xFF;
static GstStaticPadTemplate gst_rtp_h261_depay_src_template =
GST_STATIC_PAD_TEMPLATE ("src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("video/x-h261")
);
static GstStaticPadTemplate gst_rtp_h261_depay_sink_template =
GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-rtp, "
"media = (string) \"video\", "
"payload = (int) " GST_RTP_PAYLOAD_H261_STRING ", "
"clock-rate = (int) 90000, " "encoding-name = (string) \"H261\"; "
"application/x-rtp, "
"media = (string) \"video\", "
"payload = (int) " GST_RTP_PAYLOAD_DYNAMIC_STRING ", "
"clock-rate = (int) 90000, " "encoding-name = (string) \"H261\"")
);
G_DEFINE_TYPE (GstRtpH261Depay, gst_rtp_h261_depay,
GST_TYPE_RTP_BASE_DEPAYLOAD);
#define parent_class gst_rtp_h261_depay_parent_class
static GstBuffer *
gst_rtp_h261_depay_process (GstRTPBaseDepayload * depayload, GstRTPBuffer * rtp)
{
GstRtpH261Depay *depay;
GstBuffer *outbuf = NULL;
gint payload_len;
guint8 *payload;
const guint header_len = GST_RTP_H261_PAYLOAD_HEADER_LEN;
gboolean marker;
GstRtpH261PayHeader *header;
depay = GST_RTP_H261_DEPAY (depayload);
if (GST_BUFFER_IS_DISCONT (rtp->buffer)) {
GST_DEBUG_OBJECT (depay, "Discont buffer, flushing adapter");
gst_adapter_clear (depay->adapter);
depay->leftover = NO_LEFTOVER;
depay->start = FALSE;
}
payload_len = gst_rtp_buffer_get_payload_len (rtp);
payload = gst_rtp_buffer_get_payload (rtp);
marker = gst_rtp_buffer_get_marker (rtp);
if (payload_len < header_len + 1) {
/* Must have at least one byte payload */
GST_WARNING_OBJECT (depay, "Dropping packet with invalid payload length");
return NULL;
}
header = (GstRtpH261PayHeader *) payload;
GST_DEBUG_OBJECT (depay,
"payload_len: %d, header_len: %d, sbit: %d, ebit: %d, marker %d",
payload_len, header_len, header->sbit, header->ebit, marker);
payload += header_len;
payload_len -= header_len;
if (!depay->start) {
/* Check for picture start code */
guint32 bits = GST_READ_UINT32_BE (payload) << header->sbit;
if (payload_len > 4 && bits >> 12 == 0x10) {
GST_DEBUG_OBJECT (depay, "Found picture start code");
depay->start = TRUE;
} else {
GST_DEBUG_OBJECT (depay, "No picture start code yet, skipping payload");
goto skip;
}
}
if (header->sbit != 0) {
/* Take the leftover from previous packet and merge it at the beginning */
payload[0] &= 0xFF >> header->sbit;
if (depay->leftover != NO_LEFTOVER) {
/* Happens if sbit is set for first packet in frame. Then previous byte
* has already been flushed. */
payload[0] |= depay->leftover;
}
depay->leftover = NO_LEFTOVER;
}
if (header->ebit == 0) {
/* H.261 stream ends on byte boundary, take entire packet */
gst_adapter_push (depay->adapter,
gst_rtp_buffer_get_payload_subbuffer (rtp, header_len, payload_len));
} else {
/* Take the entire buffer except for the last byte, which will be kept to
* merge with next packet */
gst_adapter_push (depay->adapter,
gst_rtp_buffer_get_payload_subbuffer (rtp, header_len,
payload_len - 1));
depay->leftover = payload[payload_len - 1] & (0xFF << header->ebit);
}
skip:
if (marker) {
if (depay->start) {
guint avail;
if (depay->leftover != NO_LEFTOVER) {
GstBuffer *buf = gst_buffer_new_and_alloc (1);
gst_buffer_memset (buf, 0, depay->leftover, 1);
gst_adapter_push (depay->adapter, buf);
depay->leftover = NO_LEFTOVER;
}
avail = gst_adapter_available (depay->adapter);
outbuf = gst_adapter_take_buffer (depay->adapter, avail);
gst_rtp_drop_non_video_meta (depay, outbuf);
/* Note that the I flag does not mean intra frame, but that the entire
* stream is intra coded. */
if (header->i)
GST_BUFFER_FLAG_UNSET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
else
GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
GST_DEBUG_OBJECT (depay, "Pushing out a buffer of %u bytes", avail);
depay->start = FALSE;
} else {
depay->start = TRUE;
}
}
return outbuf;
}
static gboolean
gst_rtp_h261_depay_setcaps (GstRTPBaseDepayload * filter, GstCaps * caps)
{
GstCaps *srccaps;
srccaps = gst_caps_new_empty_simple ("video/x-h261");
gst_pad_set_caps (GST_RTP_BASE_DEPAYLOAD_SRCPAD (filter), srccaps);
gst_caps_unref (srccaps);
return TRUE;
}
static GstStateChangeReturn
gst_rtp_h261_depay_change_state (GstElement * element,
GstStateChange transition)
{
GstRtpH261Depay *depay;
GstStateChangeReturn ret;
depay = GST_RTP_H261_DEPAY (element);
switch (transition) {
case GST_STATE_CHANGE_NULL_TO_READY:
break;
case GST_STATE_CHANGE_READY_TO_PAUSED:
gst_adapter_clear (depay->adapter);
depay->start = FALSE;
break;
default:
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
switch (transition) {
case GST_STATE_CHANGE_READY_TO_NULL:
break;
default:
break;
}
return ret;
}
static void
gst_rtp_h261_depay_dispose (GObject * object)
{
GstRtpH261Depay *depay;
depay = GST_RTP_H261_DEPAY (object);
if (depay->adapter) {
gst_object_unref (depay->adapter);
depay->adapter = NULL;
}
G_OBJECT_CLASS (parent_class)->dispose (object);
}
static void
gst_rtp_h261_depay_class_init (GstRtpH261DepayClass * klass)
{
GObjectClass *gobject_class;
GstElementClass *gstelement_class;
GstRTPBaseDepayloadClass *gstrtpbasedepayload_class;
gobject_class = G_OBJECT_CLASS (klass);
gstelement_class = GST_ELEMENT_CLASS (klass);
gstrtpbasedepayload_class = GST_RTP_BASE_DEPAYLOAD_CLASS (klass);
gst_element_class_add_static_pad_template (gstelement_class,
&gst_rtp_h261_depay_src_template);
gst_element_class_add_static_pad_template (gstelement_class,
&gst_rtp_h261_depay_sink_template);
gst_element_class_set_static_metadata (gstelement_class,
"RTP H261 depayloader", "Codec/Depayloader/Network/RTP",
"Extracts H261 video from RTP packets (RFC 4587)",
"Stian Selnes <stian@pexip.com>");
gstrtpbasedepayload_class->process_rtp_packet = gst_rtp_h261_depay_process;
gstrtpbasedepayload_class->set_caps = gst_rtp_h261_depay_setcaps;
gobject_class->dispose = gst_rtp_h261_depay_dispose;
gstelement_class->change_state = gst_rtp_h261_depay_change_state;
GST_DEBUG_CATEGORY_INIT (rtph261depay_debug, "rtph261depay", 0,
"H261 Video RTP Depayloader");
}
static void
gst_rtp_h261_depay_init (GstRtpH261Depay * depay)
{
depay->adapter = gst_adapter_new ();
depay->leftover = NO_LEFTOVER;
}
gboolean
gst_rtp_h261_depay_plugin_init (GstPlugin * plugin)
{
return gst_element_register (plugin, "rtph261depay",
GST_RANK_SECONDARY, GST_TYPE_RTP_H261_DEPAY);
}