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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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294 lines
8.7 KiB
C
294 lines
8.7 KiB
C
/* GStreamer
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*
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* Copyright (C) <2014> Stian Selnes <stian@pexip.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:element-rtph261depay
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* @title: rtph261depay
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* @see_also: rtph261pay
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*
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* Extract encoded H.261 video frames from RTP packets according to RFC 4587.
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* For detailed information see: https://www.rfc-editor.org/rfc/rfc4587.txt
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*
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* The depayloader takes an RTP packet and extracts its H.261 stream. It
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* aggregates the extracted stream until a complete frame is received before
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* it pushes it downstream.
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*
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* ## Example pipeline
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* |[
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* gst-launch-1.0 udpsrc caps='application/x-rtp, payload=31' ! rtph261depay ! avdec_h261 ! autovideosink
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* ]| This example pipeline will depayload and decode an RTP H.261 video stream.
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* Refer to the rtph261pay example to create the RTP stream.
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*
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <string.h>
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#include <gst/rtp/gstrtpbuffer.h>
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#include <gst/video/video.h>
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#include "gstrtph261depay.h"
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#include "gstrtph261pay.h" /* GstRtpH261PayHeader */
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#include "gstrtputils.h"
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GST_DEBUG_CATEGORY_STATIC (rtph261depay_debug);
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#define GST_CAT_DEFAULT (rtph261depay_debug)
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static const guint8 NO_LEFTOVER = 0xFF;
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static GstStaticPadTemplate gst_rtp_h261_depay_src_template =
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GST_STATIC_PAD_TEMPLATE ("src",
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GST_PAD_SRC,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("video/x-h261")
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);
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static GstStaticPadTemplate gst_rtp_h261_depay_sink_template =
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GST_STATIC_PAD_TEMPLATE ("sink",
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GST_PAD_SINK,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("application/x-rtp, "
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"media = (string) \"video\", "
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"payload = (int) " GST_RTP_PAYLOAD_H261_STRING ", "
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"clock-rate = (int) 90000, " "encoding-name = (string) \"H261\"; "
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"application/x-rtp, "
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"media = (string) \"video\", "
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"payload = (int) " GST_RTP_PAYLOAD_DYNAMIC_STRING ", "
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"clock-rate = (int) 90000, " "encoding-name = (string) \"H261\"")
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);
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G_DEFINE_TYPE (GstRtpH261Depay, gst_rtp_h261_depay,
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GST_TYPE_RTP_BASE_DEPAYLOAD);
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#define parent_class gst_rtp_h261_depay_parent_class
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static GstBuffer *
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gst_rtp_h261_depay_process (GstRTPBaseDepayload * depayload, GstRTPBuffer * rtp)
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{
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GstRtpH261Depay *depay;
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GstBuffer *outbuf = NULL;
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gint payload_len;
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guint8 *payload;
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const guint header_len = GST_RTP_H261_PAYLOAD_HEADER_LEN;
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gboolean marker;
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GstRtpH261PayHeader *header;
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depay = GST_RTP_H261_DEPAY (depayload);
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if (GST_BUFFER_IS_DISCONT (rtp->buffer)) {
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GST_DEBUG_OBJECT (depay, "Discont buffer, flushing adapter");
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gst_adapter_clear (depay->adapter);
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depay->leftover = NO_LEFTOVER;
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depay->start = FALSE;
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}
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payload_len = gst_rtp_buffer_get_payload_len (rtp);
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payload = gst_rtp_buffer_get_payload (rtp);
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marker = gst_rtp_buffer_get_marker (rtp);
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if (payload_len < header_len + 1) {
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/* Must have at least one byte payload */
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GST_WARNING_OBJECT (depay, "Dropping packet with invalid payload length");
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return NULL;
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}
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header = (GstRtpH261PayHeader *) payload;
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GST_DEBUG_OBJECT (depay,
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"payload_len: %d, header_len: %d, sbit: %d, ebit: %d, marker %d",
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payload_len, header_len, header->sbit, header->ebit, marker);
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payload += header_len;
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payload_len -= header_len;
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if (!depay->start) {
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/* Check for picture start code */
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guint32 bits = GST_READ_UINT32_BE (payload) << header->sbit;
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if (payload_len > 4 && bits >> 12 == 0x10) {
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GST_DEBUG_OBJECT (depay, "Found picture start code");
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depay->start = TRUE;
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} else {
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GST_DEBUG_OBJECT (depay, "No picture start code yet, skipping payload");
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goto skip;
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}
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}
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if (header->sbit != 0) {
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/* Take the leftover from previous packet and merge it at the beginning */
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payload[0] &= 0xFF >> header->sbit;
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if (depay->leftover != NO_LEFTOVER) {
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/* Happens if sbit is set for first packet in frame. Then previous byte
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* has already been flushed. */
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payload[0] |= depay->leftover;
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}
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depay->leftover = NO_LEFTOVER;
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}
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if (header->ebit == 0) {
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/* H.261 stream ends on byte boundary, take entire packet */
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gst_adapter_push (depay->adapter,
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gst_rtp_buffer_get_payload_subbuffer (rtp, header_len, payload_len));
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} else {
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/* Take the entire buffer except for the last byte, which will be kept to
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* merge with next packet */
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gst_adapter_push (depay->adapter,
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gst_rtp_buffer_get_payload_subbuffer (rtp, header_len,
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payload_len - 1));
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depay->leftover = payload[payload_len - 1] & (0xFF << header->ebit);
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}
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skip:
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if (marker) {
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if (depay->start) {
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guint avail;
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if (depay->leftover != NO_LEFTOVER) {
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GstBuffer *buf = gst_buffer_new_and_alloc (1);
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gst_buffer_memset (buf, 0, depay->leftover, 1);
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gst_adapter_push (depay->adapter, buf);
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depay->leftover = NO_LEFTOVER;
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}
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avail = gst_adapter_available (depay->adapter);
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outbuf = gst_adapter_take_buffer (depay->adapter, avail);
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gst_rtp_drop_non_video_meta (depay, outbuf);
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/* Note that the I flag does not mean intra frame, but that the entire
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* stream is intra coded. */
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if (header->i)
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GST_BUFFER_FLAG_UNSET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
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else
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GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
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GST_DEBUG_OBJECT (depay, "Pushing out a buffer of %u bytes", avail);
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depay->start = FALSE;
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} else {
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depay->start = TRUE;
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}
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}
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return outbuf;
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}
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static gboolean
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gst_rtp_h261_depay_setcaps (GstRTPBaseDepayload * filter, GstCaps * caps)
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{
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GstCaps *srccaps;
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srccaps = gst_caps_new_empty_simple ("video/x-h261");
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gst_pad_set_caps (GST_RTP_BASE_DEPAYLOAD_SRCPAD (filter), srccaps);
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gst_caps_unref (srccaps);
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return TRUE;
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}
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static GstStateChangeReturn
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gst_rtp_h261_depay_change_state (GstElement * element,
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GstStateChange transition)
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{
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GstRtpH261Depay *depay;
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GstStateChangeReturn ret;
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depay = GST_RTP_H261_DEPAY (element);
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switch (transition) {
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case GST_STATE_CHANGE_NULL_TO_READY:
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break;
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case GST_STATE_CHANGE_READY_TO_PAUSED:
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gst_adapter_clear (depay->adapter);
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depay->start = FALSE;
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break;
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default:
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break;
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}
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ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
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switch (transition) {
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case GST_STATE_CHANGE_READY_TO_NULL:
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break;
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default:
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break;
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}
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return ret;
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}
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static void
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gst_rtp_h261_depay_dispose (GObject * object)
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{
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GstRtpH261Depay *depay;
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depay = GST_RTP_H261_DEPAY (object);
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if (depay->adapter) {
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gst_object_unref (depay->adapter);
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depay->adapter = NULL;
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}
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G_OBJECT_CLASS (parent_class)->dispose (object);
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}
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static void
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gst_rtp_h261_depay_class_init (GstRtpH261DepayClass * klass)
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{
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GObjectClass *gobject_class;
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GstElementClass *gstelement_class;
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GstRTPBaseDepayloadClass *gstrtpbasedepayload_class;
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gobject_class = G_OBJECT_CLASS (klass);
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gstelement_class = GST_ELEMENT_CLASS (klass);
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gstrtpbasedepayload_class = GST_RTP_BASE_DEPAYLOAD_CLASS (klass);
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gst_element_class_add_static_pad_template (gstelement_class,
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&gst_rtp_h261_depay_src_template);
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gst_element_class_add_static_pad_template (gstelement_class,
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&gst_rtp_h261_depay_sink_template);
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gst_element_class_set_static_metadata (gstelement_class,
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"RTP H261 depayloader", "Codec/Depayloader/Network/RTP",
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"Extracts H261 video from RTP packets (RFC 4587)",
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"Stian Selnes <stian@pexip.com>");
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gstrtpbasedepayload_class->process_rtp_packet = gst_rtp_h261_depay_process;
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gstrtpbasedepayload_class->set_caps = gst_rtp_h261_depay_setcaps;
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gobject_class->dispose = gst_rtp_h261_depay_dispose;
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gstelement_class->change_state = gst_rtp_h261_depay_change_state;
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GST_DEBUG_CATEGORY_INIT (rtph261depay_debug, "rtph261depay", 0,
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"H261 Video RTP Depayloader");
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}
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static void
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gst_rtp_h261_depay_init (GstRtpH261Depay * depay)
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{
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depay->adapter = gst_adapter_new ();
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depay->leftover = NO_LEFTOVER;
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}
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gboolean
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gst_rtp_h261_depay_plugin_init (GstPlugin * plugin)
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{
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return gst_element_register (plugin, "rtph261depay",
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GST_RANK_SECONDARY, GST_TYPE_RTP_H261_DEPAY);
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}
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