/* GStreamer * * Copyright (C) <2014> Stian Selnes * * 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 * @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 #include #include "gstrtph261depay.h" #include "gstrtph261pay.h" /* GstRtpH261PayHeader */ 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 < 4) { GST_WARNING_OBJECT (depay, "Dropping packet with payload length invalid 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); /* 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_pad_template (gstelement_class, gst_static_pad_template_get (&gst_rtp_h261_depay_src_template)); gst_element_class_add_pad_template (gstelement_class, gst_static_pad_template_get (&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 "); 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); }