rtp: add H.261 RTP payloader and depayloader

Implementation according to RFC 4587.

Payloader create fragments on MB boundaries in order to match MTU size
the best it can. Some decoders/depayloaders in the wild are very strict
about receiving a continuous bit-stream (e.g. no no-op bits between
frames), so the payloader will shift the compressed bit-stream of a
frame to align with the last significant bit of the previous frame.

Depayloader does not try to be fancy in case of packet loss. It simply
drops all packets for a frame if there is a loss, keeping it simple.

https://bugzilla.gnome.org/show_bug.cgi?id=751886

gst/rtp/Makefile.am

@@ -38,6 +38,8 @@ libgstrtp_la_SOURCES = \
 	gstrtpgsmpay.c \
 	gstrtpamrdepay.c \
 	gstrtpamrpay.c \
+	gstrtph261pay.c \
+	gstrtph261depay.c \
 	gstrtph263pdepay.c \
 	gstrtph263ppay.c \
 	gstrtph263depay.c \
@@ -139,6 +141,8 @@ noinst_HEADERS =			\
 	gstrtpmpapay.h \
 	gstrtpmpvdepay.h \
 	gstrtpmpvpay.h \
+	gstrtph261pay.h \
+	gstrtph261depay.h \
 	gstrtph263pdepay.h \
 	gstrtph263ppay.h \
 	gstrtph263depay.h \

gst/rtp/gstrtp.c

@@ -56,6 +56,8 @@
 #include "gstrtpmparobustdepay.h"
 #include "gstrtpmpvdepay.h"
 #include "gstrtpmpvpay.h"
+#include "gstrtph261pay.h"
+#include "gstrtph261depay.h"
 #include "gstrtph263pdepay.h"
 #include "gstrtph263ppay.h"
 #include "gstrtph263depay.h"
@@ -204,6 +206,12 @@ plugin_init (GstPlugin * plugin)
   if (!gst_rtp_mpv_pay_plugin_init (plugin))
     return FALSE;
 
+  if (!gst_rtp_h261_pay_plugin_init (plugin))
+    return FALSE;
+
+  if (!gst_rtp_h261_depay_plugin_init (plugin))
+    return FALSE;
+
   if (!gst_rtp_h263p_pay_plugin_init (plugin))
     return FALSE;
 

gst/rtp/gstrtph261depay.c

@@ -0,0 +1,277 @@
+/* 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#include <string.h>
+
+#include <gst/rtp/gstrtpbuffer.h>
+#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, GstBuffer * buf)
+{
+  GstRtpH261Depay *depay;
+  GstBuffer *outbuf;
+  gint payload_len;
+  guint8 *payload;
+  const guint header_len = GST_RTP_H261_PAYLOAD_HEADER_LEN;
+  gboolean marker;
+  GstRtpH261PayHeader *header;
+  GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
+
+  depay = GST_RTP_H261_DEPAY (depayload);
+
+  if (GST_BUFFER_IS_DISCONT (buf)) {
+    GST_DEBUG_OBJECT (depay, "Discont buffer, flushing adapter");
+    gst_adapter_clear (depay->adapter);
+    depay->leftover = NO_LEFTOVER;
+    depay->start = FALSE;
+  }
+
+  gst_rtp_buffer_map (buf, GST_MAP_READ, &rtp);
+
+  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");
+    gst_rtp_buffer_unmap (&rtp);
+    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);
+      gst_rtp_base_depayload_push (depayload, outbuf);
+      depay->start = FALSE;
+    } else {
+      depay->start = TRUE;
+    }
+  }
+  gst_rtp_buffer_unmap (&rtp);
+
+  return NULL;
+}
+
+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 <stian@pexip.com>");
+
+  gstrtpbasedepayload_class->process = 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);
+}

gst/rtp/gstrtph261depay.h

@@ -0,0 +1,60 @@
+/* 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.
+ */
+
+#ifndef __GST_RTP_H261_DEPAY_H__
+#define __GST_RTP_H261_DEPAY_H__
+
+#include <gst/gst.h>
+#include <gst/base/gstadapter.h>
+#include <gst/rtp/gstrtpbasedepayload.h>
+
+G_BEGIN_DECLS
+#define GST_TYPE_RTP_H261_DEPAY \
+  (gst_rtp_h261_depay_get_type())
+#define GST_RTP_H261_DEPAY(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_RTP_H261_DEPAY,GstRtpH261Depay))
+#define GST_RTP_H261_DEPAY_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_RTP_H261_DEPAY,GstRtpH261DepayClass))
+#define GST_IS_RTP_H261_DEPAY(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_RTP_H261_DEPAY))
+#define GST_IS_RTP_H261_DEPAY_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_RTP_H261_DEPAY))
+typedef struct _GstRtpH261Depay GstRtpH261Depay;
+typedef struct _GstRtpH261DepayClass GstRtpH261DepayClass;
+
+struct _GstRtpH261Depay
+{
+  GstRTPBaseDepayload depayload;
+
+  GstAdapter *adapter;
+  gboolean start;
+  guint8 leftover;
+};
+
+struct _GstRtpH261DepayClass
+{
+  GstRTPBaseDepayloadClass parent_class;
+};
+
+GType gst_rtp_h261_depay_get_type (void);
+
+gboolean gst_rtp_h261_depay_plugin_init (GstPlugin * plugin);
+
+G_END_DECLS
+#endif /* __GST_RTP_H261_DEPAY_H__ */

gst/rtp/gstrtph261pay.h

@@ -0,0 +1,100 @@
+/* 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.
+ *
+ * Author: Dejan Sakelsak sahel@kiberpipa.org
+ */
+
+#ifndef __GST_RTP_H261_PAY_H__
+#define __GST_RTP_H261_PAY_H__
+
+#include <gst/gst.h>
+#include <gst/rtp/gstrtpbasepayload.h>
+#include <gst/base/gstadapter.h>
+
+G_BEGIN_DECLS
+#define GST_TYPE_RTP_H261_PAY                   \
+  (gst_rtp_h261_pay_get_type())
+#define GST_RTP_H261_PAY(obj)                                           \
+  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_RTP_H261_PAY,GstRtpH261Pay))
+#define GST_RTP_H261_PAY_CLASS(klass)                                   \
+  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_RTP_H261_PAY,GstRtpH261PayClass))
+#define GST_IS_RTP_H261_PAY(obj)                            \
+  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_RTP_H261_PAY))
+#define GST_IS_RTP_H261_PAY_CLASS(klass)                    \
+  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_RTP_H261_PAY))
+typedef struct _GstRtpH261PayClass GstRtpH261PayClass;
+typedef struct _GstRtpH261Pay GstRtpH261Pay;
+
+struct _GstRtpH261Pay
+{
+  GstRTPBasePayload payload;
+
+  GstAdapter *adapter;
+  gint offset;
+  GstClockTime timestamp;
+};
+
+struct _GstRtpH261PayClass
+{
+  GstRTPBasePayloadClass parent_class;
+};
+
+typedef struct _GstRtpH261PayHeader
+{
+#if G_BYTE_ORDER == G_LITTLE_ENDIAN
+  unsigned int v:1;             /* Motion vector flag */
+  unsigned int i:1;             /* Intra encoded data */
+  unsigned int ebit:3;          /* End position */
+  unsigned int sbit:3;          /* Start position */
+
+  unsigned int mbap1:4;         /* MB address predictor - part1 */
+  unsigned int gobn:4;          /* GOB number */
+
+  unsigned int hmvd1:2;         /* Horizontal motion vector data - part1 */
+  unsigned int quant:5;         /* Quantizer */
+  unsigned int mbap2:1;         /* MB address predictor - part2 */
+
+  unsigned int vmvd:5;          /* Horizontal motion vector data - part1 */
+  unsigned int hmvd2:3;         /* Vertical motion vector data */
+#elif G_BYTE_ORDER == G_BIG_ENDIAN
+  unsigned int sbit:3;          /* Start position */
+  unsigned int ebit:3;          /* End position */
+  unsigned int i:1;             /* Intra encoded data */
+  unsigned int v:1;             /* Motion vector flag */
+
+  unsigned int gobn:4;          /* GOB number */
+  unsigned int mbap1:4;         /* MB address predictor - part1 */
+
+  unsigned int mbap2:1;         /* MB address predictor - part2 */
+  unsigned int quant:5;         /* Quantizer */
+  unsigned int hmvd1:2;         /* Horizontal motion vector data - part1 */
+
+  unsigned int hmvd2:3;         /* Vertical motion vector data */
+  unsigned int vmvd:5;          /* Horizontal motion vector data - part1 */
+#else
+#error "G_BYTE_ORDER should be big or little endian."
+#endif
+} GstRtpH261PayHeader;
+#define GST_RTP_H261_PAYLOAD_HEADER_LEN 4
+
+GType gst_rtp_h261_pay_get_type (void);
+
+gboolean gst_rtp_h261_pay_plugin_init (GstPlugin * plugin);
+
+G_END_DECLS
+#endif /* __GST_RTP_H261_PAY_H__ */

tests/check/elements/rtp-payloading.c

@@ -464,6 +464,22 @@ GST_START_TEST (rtp_mpa)
 }
 
 GST_END_TEST;
+
+static const guint8 rtp_h261_frame_data[] = {
+  0x00, 0x01, 0x00, 0x06, 0x00, 0x01, 0x11, 0x00, 0x00, 0x4c, 0x40, 0x00,
+  0x15, 0x10,
+};
+static int rtp_h261_frame_data_size = 14;
+static int rtp_h261_frame_count = 1;
+
+GST_START_TEST (rtp_h261)
+{
+  rtp_pipeline_test (rtp_h261_frame_data, rtp_h261_frame_data_size,
+      rtp_h261_frame_count, "video/x-h261", "rtph261pay", "rtph261depay",
+      0, 0, FALSE);
+}
+GST_END_TEST;
+
 static const guint8 rtp_h263_frame_data[] =
     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
@@ -945,6 +961,7 @@ rtp_payloading_suite (void)
   tcase_add_test (tc_chain, rtp_pcma);
   tcase_add_test (tc_chain, rtp_pcmu);
   tcase_add_test (tc_chain, rtp_mpa);
+  tcase_add_test (tc_chain, rtp_h261);
   tcase_add_test (tc_chain, rtp_h263);
   tcase_add_test (tc_chain, rtp_h263p);
   tcase_add_test (tc_chain, rtp_h264);