debugutils: Added new jitterer element

This element can be configured to add jitter and/or drift to incoming
buffers' PTS, DTS, or both. Amplitude and average of jitter and drift
are configurable.

https://bugzilla.gnome.org/show_bug.cgi?id=787358

gst/debugutils/Makefile.am

@@ -8,7 +8,8 @@ libgstdebugutilsbad_la_SOURCES = \
 	gstchopmydata.c \
 	gstcompare.c \
 	gstwatchdog.c \
-	gsterrorignore.c
+	gsterrorignore.c \
+	gstjitterer.c
 
 libgstdebugutilsbad_la_CFLAGS = $(GST_CFLAGS) $(GST_BASE_CFLAGS) $(GST_PLUGINS_BASE_CFLAGS)
 libgstdebugutilsbad_la_LIBADD = $(GST_BASE_LIBS) $(GST_PLUGINS_BASE_LIBS) \
@@ -22,4 +23,5 @@ noinst_HEADERS = fpsdisplaysink.h \
 	gstcompare.h \
 	gstdebugspy.h \
 	gstwatchdog.h \
-	gsterrorignore.h
+	gsterrorignore.h \
+	gstjitterer.h

gst/debugutils/debugutilsbad.c

@@ -29,6 +29,7 @@ GType gst_chop_my_data_get_type (void);
 GType gst_compare_get_type (void);
 GType gst_debug_spy_get_type (void);
 GType gst_error_ignore_get_type (void);
+GType gst_jitterer_get_type (void);
 GType gst_watchdog_get_type (void);
 
 static gboolean
@@ -48,6 +49,8 @@ plugin_init (GstPlugin * plugin)
       gst_watchdog_get_type ());
   gst_element_register (plugin, "errorignore", GST_RANK_NONE,
       gst_error_ignore_get_type ());
+  gst_element_register (plugin, "jitterer", GST_RANK_NONE,
+      gst_jitterer_get_type ());
 
   return TRUE;
 }

gst/debugutils/gstjitterer.c

@@ -0,0 +1,387 @@
+/*
+ * GStreamer
+ * Copyright (C) 2017 Vivia Nikolaidou <vivia@ahiru.eu>
+ *
+ * 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-jitterer
+ * @title: jitterer
+ *
+ * Adds jitter and/or drift to a buffer's PTS and/or DTS. Amplitude and
+ * average of jitter and drift are configurable.
+ *
+ * ## Example launch line
+ * |[
+ * gst-launch-1.0 videotestsrc ! jitterer drift-average=100 drift-amplitude=10 ! autovideosink
+ * ]|
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstjitterer.h"
+
+#define GST_CAT_DEFAULT gst_jitterer_debug
+GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
+
+enum
+{
+  PROP_0,
+  PROP_JITTER_AMPL,
+  PROP_JITTER_AVG,
+  PROP_DRIFT_AMPL,
+  PROP_DRIFT_AVG,
+  PROP_CHANGE_PTS,
+  PROP_CHANGE_DTS
+};
+
+static void gst_jitterer_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec);
+static void gst_jitterer_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec);
+static void gst_jitterer_finalize (GObject * object);
+
+static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS_ANY);
+
+static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS_ANY);
+
+#define parent_class gst_jitterer_parent_class
+G_DEFINE_TYPE (GstJitterer, gst_jitterer, GST_TYPE_ELEMENT);
+
+static GstFlowReturn gst_jitterer_sink_chain (GstPad * pad,
+    GstObject * parent, GstBuffer * inbuf);
+static gboolean gst_jitterer_sink_event (GstPad * pad, GstObject * parent,
+    GstEvent * event);
+
+static void
+gst_jitterer_class_init (GstJittererClass * klass)
+{
+  GstElementClass *gstelement_class;
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  GST_DEBUG_CATEGORY_INIT (gst_jitterer_debug, "jitterer", 0,
+      "Add jitter and/or drift to buffers");
+
+  gstelement_class = (GstElementClass *) klass;
+
+  gst_element_class_set_static_metadata (gstelement_class,
+      "Jitterer", "Generic", "Add jitter and/or drift to buffers",
+      "Vivia Nikolaidou <vivia@ahiru.eu>");
+
+  gst_element_class_add_static_pad_template (gstelement_class, &src_template);
+  gst_element_class_add_static_pad_template (gstelement_class, &sink_template);
+
+  /* define virtual function pointers */
+  object_class->set_property = gst_jitterer_set_property;
+  object_class->get_property = gst_jitterer_get_property;
+  object_class->finalize = gst_jitterer_finalize;
+
+  /* define properties */
+  g_object_class_install_property (object_class, PROP_JITTER_AMPL,
+      g_param_spec_uint64 ("jitter-amplitude", "Jitter amplitude",
+          "Amplitude of the jitter to apply",
+          0, G_MAXINT64 / 2, 0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (object_class, PROP_JITTER_AVG,
+      g_param_spec_int64 ("jitter-average", "Jitter average",
+          "Average of the jitter to apply",
+          -G_MAXINT64 / 2, G_MAXINT64 / 2, 0,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (object_class, PROP_DRIFT_AMPL,
+      g_param_spec_uint64 ("drift-amplitude", "Drift amplitude",
+          "Amplitude of the drift to apply",
+          0, G_MAXINT64 / 2, 0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (object_class, PROP_DRIFT_AVG,
+      g_param_spec_int64 ("drift-average", "Drift average",
+          "Average of the drift to apply",
+          -G_MAXINT64 / 2, G_MAXINT64 / 2, 0,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (object_class, PROP_CHANGE_PTS,
+      g_param_spec_boolean ("change-pts", "Change PTS",
+          "Whether to change the PTS of incoming buffers",
+          TRUE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (object_class, PROP_CHANGE_DTS,
+      g_param_spec_boolean ("change-dts", "Change DTS",
+          "Whether to change the DTS of incoming buffers",
+          TRUE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+}
+
+static void
+gst_jitterer_init (GstJitterer * self)
+{
+  self->sinkpad = gst_pad_new_from_static_template (&sink_template, "sink");
+  gst_pad_set_chain_function (self->sinkpad,
+      GST_DEBUG_FUNCPTR (gst_jitterer_sink_chain));
+  gst_pad_set_event_function (self->sinkpad,
+      GST_DEBUG_FUNCPTR (gst_jitterer_sink_event));
+  GST_PAD_SET_PROXY_ALLOCATION (self->sinkpad);
+  GST_PAD_SET_PROXY_CAPS (self->sinkpad);
+  GST_PAD_SET_PROXY_SCHEDULING (self->sinkpad);
+  gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);
+
+  self->srcpad = gst_pad_new_from_static_template (&src_template, "src");
+  gst_pad_use_fixed_caps (self->srcpad);
+  GST_PAD_SET_PROXY_ALLOCATION (self->srcpad);
+  GST_PAD_SET_PROXY_CAPS (self->srcpad);
+  GST_PAD_SET_PROXY_SCHEDULING (self->srcpad);
+  gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
+
+  self->jitter_ampl = 0;
+  self->jitter_avg = 0;
+  self->drift_ampl = 0;
+  self->drift_avg = 0;
+  self->change_pts = TRUE;
+  self->change_dts = TRUE;
+  self->prev_pts = GST_CLOCK_TIME_NONE;
+
+  self->dts_drift_so_far = 0;
+  self->pts_drift_so_far = 0;
+  self->rand = g_rand_new ();
+}
+
+static void
+gst_jitterer_finalize (GObject * object)
+{
+  GstJitterer *self = GST_JITTERER (object);
+
+  g_rand_free (self->rand);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gst_jitterer_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  GstJitterer *self = GST_JITTERER (object);
+
+  switch (prop_id) {
+    case PROP_JITTER_AMPL:
+      self->jitter_ampl = g_value_get_uint64 (value);
+      break;
+    case PROP_JITTER_AVG:
+      self->jitter_avg = g_value_get_int64 (value);
+      break;
+    case PROP_DRIFT_AMPL:
+      self->drift_ampl = g_value_get_uint64 (value);
+      break;
+    case PROP_DRIFT_AVG:
+      self->drift_avg = g_value_get_int64 (value);
+      break;
+    case PROP_CHANGE_PTS:
+      self->change_pts = g_value_get_boolean (value);
+      break;
+    case PROP_CHANGE_DTS:
+      self->change_dts = g_value_get_boolean (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+gst_jitterer_get_property (GObject * object, guint prop_id, GValue * value,
+    GParamSpec * pspec)
+{
+  GstJitterer *self = GST_JITTERER (object);
+
+  switch (prop_id) {
+    case PROP_JITTER_AMPL:
+      g_value_set_uint64 (value, self->jitter_ampl);
+      break;
+    case PROP_JITTER_AVG:
+      g_value_set_int64 (value, self->jitter_avg);
+      break;
+    case PROP_DRIFT_AMPL:
+      g_value_set_uint64 (value, self->drift_ampl);
+      break;
+    case PROP_DRIFT_AVG:
+      g_value_set_int64 (value, self->drift_avg);
+      break;
+    case PROP_CHANGE_PTS:
+      g_value_set_boolean (value, self->change_pts);
+      break;
+    case PROP_CHANGE_DTS:
+      g_value_set_boolean (value, self->change_dts);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static gint64
+gst_jitterer_rand_uint64_range (GRand * rand, gint64 min, gint64 max)
+{
+  gint64 dist;
+
+  g_assert (max > min);
+  dist = max - min;
+
+  if (G_LIKELY (dist < G_MAXINT32)) {
+    return g_rand_int_range (rand, 0, dist) + min;
+  } else {
+    /* This code is based on g_rand_int_range source */
+    gint64 ret = max + 1;
+    /* maxvalue is set to the predecessor of the greatest
+     * multiple of dist less or equal 2^64.
+     */
+    guint64 maxvalue;
+    if (dist <= 0x8000000000000000u) {  /* 2^63 */
+      /* maxvalue = 2^64 - 1 - (2^64 % dist) */
+      guint64 leftover = (0x8000000000000000u % dist) * 2;
+      if (leftover >= dist)
+        leftover -= dist;
+      maxvalue = 0xffffffffffffffffu - leftover;
+    } else {
+      maxvalue = dist - 1;
+    }
+    do {
+      gint32 highrand, lowrand;
+
+      highrand = g_rand_int (rand);
+      lowrand = g_rand_int (rand);
+      ret = ((((gint64) highrand) << 32) | lowrand);
+    } while (ret > maxvalue);
+    ret %= dist;
+    return ret;
+  }
+}
+
+static gboolean
+gst_jitterer_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
+{
+  GstJitterer *self = GST_JITTERER (parent);
+
+  switch (GST_EVENT_TYPE (event)) {
+    case GST_EVENT_SEGMENT:
+    case GST_EVENT_FLUSH_STOP:
+      self->prev_pts = GST_CLOCK_TIME_NONE;
+      break;
+    default:
+      break;
+  }
+  return gst_pad_event_default (pad, parent, event);
+}
+
+static GstFlowReturn
+gst_jitterer_sink_chain (GstPad * pad, GstObject * parent, GstBuffer * inbuf)
+{
+  GstJitterer *self = GST_JITTERER (parent);
+
+  if (self->jitter_ampl > 0) {
+    gint64 min, max;
+    gint64 jitter;
+
+    min = self->jitter_avg - self->jitter_ampl / 2;
+    max = self->jitter_avg + self->jitter_ampl / 2;
+
+    if (self->change_pts && GST_BUFFER_PTS (inbuf) != GST_CLOCK_TIME_NONE) {
+      jitter = gst_jitterer_rand_uint64_range (self->rand, min, max);
+      if (GST_BUFFER_PTS (inbuf) + jitter > 0)
+        GST_BUFFER_PTS (inbuf) = GST_BUFFER_PTS (inbuf) + jitter;
+    }
+    if (self->change_dts && GST_BUFFER_DTS (inbuf) != GST_CLOCK_TIME_NONE) {
+      jitter = gst_jitterer_rand_uint64_range (self->rand, min, max);
+      if (GST_BUFFER_DTS (inbuf) + jitter > 0)
+        GST_BUFFER_DTS (inbuf) = GST_BUFFER_DTS (inbuf) + jitter;
+    }
+  } else {
+    if (self->change_pts && GST_BUFFER_PTS (inbuf) != GST_CLOCK_TIME_NONE)
+      GST_BUFFER_PTS (inbuf) = GST_BUFFER_PTS (inbuf) + self->jitter_avg;
+    if (self->change_dts && GST_BUFFER_DTS (inbuf) != GST_CLOCK_TIME_NONE)
+      GST_BUFFER_DTS (inbuf) = GST_BUFFER_DTS (inbuf) + self->jitter_avg;
+  }
+
+  if (self->prev_pts != GST_CLOCK_TIME_NONE) {
+    GstClockTimeDiff drift_avg_per_frame;
+    GstClockTime pts_diff = GST_BUFFER_PTS (inbuf) - self->prev_pts;
+
+    if (self->drift_avg == 0) {
+      drift_avg_per_frame = 0;
+    } else if (self->drift_avg > 0) {
+      drift_avg_per_frame =
+          gst_util_uint64_scale (self->drift_avg, pts_diff, GST_SECOND);
+    } else {
+      drift_avg_per_frame =
+          -gst_util_uint64_scale (-self->drift_avg, pts_diff, GST_SECOND);
+    }
+
+    if (self->drift_ampl > 0) {
+      gint min, max;
+      GstClockTime drift_ampl_per_frame;
+
+      drift_ampl_per_frame =
+          gst_util_uint64_scale (self->drift_ampl, pts_diff, GST_SECOND);
+
+      min = drift_avg_per_frame - drift_ampl_per_frame / 2;
+      max = drift_avg_per_frame + drift_ampl_per_frame / 2;
+
+      if (self->change_pts && GST_BUFFER_PTS (inbuf) != GST_CLOCK_TIME_NONE) {
+        /* FIXME: if (min == max) means the amplitude is too small, make a
+         * probabilistic +1 or -1 instead */
+        if (min == max)
+          self->pts_drift_so_far += drift_avg_per_frame;
+        else
+          self->pts_drift_so_far +=
+              gst_jitterer_rand_uint64_range (self->rand, min, max);
+        if (GST_BUFFER_PTS (inbuf) + self->pts_drift_so_far > 0)
+          GST_BUFFER_PTS (inbuf) =
+              GST_BUFFER_PTS (inbuf) + self->pts_drift_so_far;
+      }
+      if (self->change_dts && GST_BUFFER_DTS (inbuf) != GST_CLOCK_TIME_NONE) {
+        if (min == max)
+          self->pts_drift_so_far += drift_avg_per_frame;
+        else
+          self->dts_drift_so_far +=
+              gst_jitterer_rand_uint64_range (self->rand, min, max);
+        if (GST_BUFFER_DTS (inbuf) + self->dts_drift_so_far > 0)
+          GST_BUFFER_DTS (inbuf) =
+              GST_BUFFER_DTS (inbuf) + self->dts_drift_so_far;
+      }
+    } else {
+      if (self->change_pts && GST_BUFFER_PTS (inbuf) != GST_CLOCK_TIME_NONE) {
+        self->pts_drift_so_far += drift_avg_per_frame;
+        GST_BUFFER_PTS (inbuf) =
+            GST_BUFFER_PTS (inbuf) + self->pts_drift_so_far;
+      }
+      if (self->change_dts && GST_BUFFER_DTS (inbuf) != GST_CLOCK_TIME_NONE) {
+        self->dts_drift_so_far += drift_avg_per_frame;
+        GST_BUFFER_DTS (inbuf) =
+            GST_BUFFER_DTS (inbuf) + self->dts_drift_so_far;
+      }
+    }
+  }
+  self->prev_pts = GST_BUFFER_PTS (inbuf);
+
+  return gst_pad_push (self->srcpad, inbuf);
+}

gst/debugutils/gstjitterer.h

@@ -0,0 +1,67 @@
+/* 
+ * GStreamer
+ * Copyright (C) 2017 Vivia Nikolaidou <vivia@ahiru.eu>
+ *
+ * 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.
+ */
+ 
+#ifndef __GST_JITTERER_H__
+#define __GST_JITTERER_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+
+#define GST_TYPE_JITTERER            (gst_jitterer_get_type())
+#define GST_JITTERER(obj)            (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_JITTERER,GstJitterer))
+#define GST_IS_JITTERER(obj)         (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_JITTERER))
+#define GST_JITTERER_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST((klass) ,GST_TYPE_JITTERER,GstJittererClass))
+#define GST_IS_JITTERER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass) ,GST_TYPE_JITTERER))
+#define GST_JITTERER_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS((obj) ,GST_TYPE_JITTERER,GstJittererClass))
+
+typedef struct _GstJitterer      GstJitterer;
+typedef struct _GstJittererClass GstJittererClass;
+
+struct _GstJitterer {
+  GstElement parent;
+
+  GstClockTime jitter_ampl;
+  GstClockTimeDiff jitter_avg;
+  GstClockTime drift_ampl;
+  GstClockTimeDiff drift_avg;
+  gboolean change_pts;
+  gboolean change_dts;
+
+  gint64 dts_drift_so_far;
+  gint64 pts_drift_so_far;
+  GRand *rand;
+  GstClockTime prev_pts;
+
+  GstPad *srcpad;
+  GstPad *sinkpad;
+};
+
+struct _GstJittererClass {
+  GstElementClass parent_class;
+};
+
+GType gst_jitterer_get_type (void);
+
+gboolean gst_jitterer_plugin_init (GstPlugin * plugin);
+
+G_END_DECLS
+
+#endif /* __GST_JITTERER_H__ */

gst/debugutils/meson.build

@@ -1,6 +1,7 @@
 debugutilsbad_sources = [
   'gstdebugspy.c',
   'gsterrorignore.c',
+  'gstjitterer.c',
   'debugutilsbad.c',
   'fpsdisplaysink.c',
   'gstchecksumsink.c',