appsrc: Add support for custom GstSegment

Add property "handle-segment-change" for user to allow pushing
custom segment event. For now, this property can work only for
time format GstSegment.
This property can be useful in case application controls timeline
of stream such as there is timestamp discontinuity but playback is
expected to be continuous. Multi-period scenario of MPEG-DASH is an
example of this use case.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/663>

diff --git a/docs/plugins/gst_plugins_cache.json b/docs/plugins/gst_plugins_cache.json
index 858445f..3dc3e20 100644 (file)
--- a/docs/plugins/gst_plugins_cache.json
+++ b/docs/plugins/gst_plugins_cache.json
@@ -504,6 +504,18 @@
                         "type": "GstFormat",
                         "writable": true
                     },
+                    "handle-segment-change": {
+                        "blurb": "Whether to detect and handle changed time format GstSegment in GstSample. User should set valid GstSegment in GstSample. Must set format property as \"time\" to enable this property",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "false",
+                        "mutable": "ready",
+                        "readable": true,
+                        "type": "gboolean",
+                        "writable": true
+                    },
                     "is-live": {
                         "blurb": "Whether to act as a live source",
                         "conditionally-available": false,

diff --git a/gst-libs/gst/app/gstappsrc.c b/gst-libs/gst/app/gstappsrc.c
index ed92e5a..ac79230 100644 (file)
--- a/gst-libs/gst/app/gstappsrc.c
+++ b/gst-libs/gst/app/gstappsrc.c
@@ -146,6 +146,9 @@ struct _GstAppSrcPrivate
 
   GstCaps *last_caps;
   GstCaps *current_caps;
+  GstSegment last_segment;
+  GstSegment current_segment;
+  gboolean pending_custom_segment;
 
   gint64 size;
   GstClockTime duration;
@@ -166,6 +169,7 @@ struct _GstAppSrcPrivate
   guint64 max_latency;
   gboolean emit_signals;
   guint min_percent;
+  gboolean handle_segment_change;
 
   Callbacks *callbacks;
 };
@@ -201,6 +205,7 @@ enum
 #define DEFAULT_PROP_MIN_PERCENT   0
 #define DEFAULT_PROP_CURRENT_LEVEL_BYTES   0
 #define DEFAULT_PROP_DURATION      GST_CLOCK_TIME_NONE
+#define DEFAULT_PROP_HANDLE_SEGMENT_CHANGE FALSE
 
 enum
 {
@@ -218,6 +223,7 @@ enum
   PROP_MIN_PERCENT,
   PROP_CURRENT_LEVEL_BYTES,
   PROP_DURATION,
+  PROP_HANDLE_SEGMENT_CHANGE,
   PROP_LAST
 };
 
@@ -439,6 +445,29 @@ gst_app_src_class_init (GstAppSrcClass * klass)
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 
   /**
+   * GstAppSrc:handle-segment-change:
+   *
+   * When enabled, appsrc will check GstSegment in GstSample which was
+   * pushed via gst_app_src_push_sample() or "push-sample" signal action.
+   * If a GstSegment is changed, corresponding segment event will be followed
+   * by next data flow.
+   *
+   * FIXME: currently only GST_FORMAT_TIME format is supported and therefore
+   * GstAppSrc::format should be time. However, possibly #GstAppSrc can support
+   * other formats.
+   *
+   * Since: 1.18
+   */
+  g_object_class_install_property (gobject_class, PROP_HANDLE_SEGMENT_CHANGE,
+      g_param_spec_boolean ("handle-segment-change", "Handle Segment Change",
+          "Whether to detect and handle changed time format GstSegment in "
+          "GstSample. User should set valid GstSegment in GstSample. "
+          "Must set format property as \"time\" to enable this property",
+          DEFAULT_PROP_HANDLE_SEGMENT_CHANGE,
+          G_PARAM_READWRITE | GST_PARAM_MUTABLE_READY |
+          G_PARAM_STATIC_STRINGS));
+
+  /**
    * GstAppSrc::need-data:
    * @appsrc: the appsrc element that emitted the signal
    * @length: the amount of bytes needed.
@@ -614,6 +643,7 @@ gst_app_src_init (GstAppSrc * appsrc)
   priv->max_latency = DEFAULT_PROP_MAX_LATENCY;
   priv->emit_signals = DEFAULT_PROP_EMIT_SIGNALS;
   priv->min_percent = DEFAULT_PROP_MIN_PERCENT;
+  priv->handle_segment_change = DEFAULT_PROP_HANDLE_SEGMENT_CHANGE;
 
   gst_base_src_set_live (GST_BASE_SRC (appsrc), DEFAULT_PROP_IS_LIVE);
 }
@@ -760,6 +790,9 @@ gst_app_src_set_property (GObject * object, guint prop_id,
     case PROP_DURATION:
       gst_app_src_set_duration (appsrc, g_value_get_uint64 (value));
       break;
+    case PROP_HANDLE_SEGMENT_CHANGE:
+      priv->handle_segment_change = g_value_get_boolean (value);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -823,6 +856,9 @@ gst_app_src_get_property (GObject * object, guint prop_id, GValue * value,
     case PROP_DURATION:
       g_value_set_uint64 (value, gst_app_src_get_duration (appsrc));
       break;
+    case PROP_HANDLE_SEGMENT_CHANGE:
+      g_value_set_boolean (value, priv->handle_segment_change);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -895,6 +931,9 @@ gst_app_src_start (GstBaseSrc * bsrc)
   g_mutex_unlock (&priv->mutex);
 
   gst_base_src_set_format (bsrc, priv->format);
+  gst_segment_init (&priv->last_segment, priv->format);
+  gst_segment_init (&priv->current_segment, priv->format);
+  priv->pending_custom_segment = FALSE;
 
   return TRUE;
 }
@@ -1056,6 +1095,9 @@ gst_app_src_do_seek (GstBaseSrc * src, GstSegment * segment)
     GST_DEBUG_OBJECT (appsrc, "flushing queue");
     g_mutex_lock (&priv->mutex);
     gst_app_src_flush_queued (appsrc, TRUE);
+    gst_segment_copy_into (segment, &priv->last_segment);
+    gst_segment_copy_into (segment, &priv->current_segment);
+    priv->pending_custom_segment = FALSE;
     g_mutex_unlock (&priv->mutex);
     priv->is_eos = FALSE;
   } else {
@@ -1258,11 +1300,9 @@ gst_app_src_create (GstBaseSrc * bsrc, guint64 offset, guint size,
         *buf = GST_BUFFER (obj);
         buf_size = gst_buffer_get_size (*buf);
         GST_LOG_OBJECT (appsrc, "have buffer %p of size %u", *buf, buf_size);
-      } else {
+      } else if (GST_IS_BUFFER_LIST (obj)) {
         GstBufferList *buffer_list;
 
-        g_assert (GST_IS_BUFFER_LIST (obj));
-
         buffer_list = GST_BUFFER_LIST (obj);
 
         buf_size = gst_buffer_list_calculate_size (buffer_list);
@@ -1272,6 +1312,29 @@ gst_app_src_create (GstBaseSrc * bsrc, guint64 offset, guint size,
 
         gst_base_src_submit_buffer_list (bsrc, buffer_list);
         *buf = NULL;
+      } else if (GST_IS_EVENT (obj)) {
+        GstEvent *event = GST_EVENT (obj);
+        const GstSegment *segment = NULL;
+
+        gst_event_parse_segment (event, &segment);
+        g_assert (segment != NULL);
+
+        if (!gst_segment_is_equal (&priv->current_segment, segment)) {
+          GST_DEBUG_OBJECT (appsrc,
+              "Update new segment %" GST_PTR_FORMAT, event);
+          if (!gst_base_src_new_segment (bsrc, segment)) {
+            GST_ERROR_OBJECT (appsrc,
+                "Couldn't set new segment %" GST_PTR_FORMAT, event);
+            ret = GST_FLOW_ERROR;
+            break;
+          }
+          gst_segment_copy_into (segment, &priv->current_segment);
+        }
+
+        gst_event_unref (event);
+        continue;
+      } else {
+        g_assert_not_reached ();
       }
 
       priv->queued_bytes -= buf_size;
@@ -1897,6 +1960,14 @@ gst_app_src_push_internal (GstAppSrc * appsrc, GstBuffer * buffer,
       break;
   }
 
+  if (priv->pending_custom_segment) {
+    GstEvent *event = gst_event_new_segment (&priv->last_segment);
+
+    GST_DEBUG_OBJECT (appsrc, "enqueue new segment %" GST_PTR_FORMAT, event);
+    gst_queue_array_push_tail (priv->queue, event);
+    priv->pending_custom_segment = FALSE;
+  }
+
   if (buflist != NULL) {
     GST_DEBUG_OBJECT (appsrc, "queueing buffer list %p", buflist);
     if (!steal_ref)
@@ -1947,6 +2018,7 @@ gst_app_src_push_buffer_full (GstAppSrc * appsrc, GstBuffer * buffer,
 static GstFlowReturn
 gst_app_src_push_sample_internal (GstAppSrc * appsrc, GstSample * sample)
 {
+  GstAppSrcPrivate *priv = appsrc->priv;
   GstBufferList *buffer_list;
   GstBuffer *buffer;
   GstCaps *caps;
@@ -1960,6 +2032,30 @@ gst_app_src_push_sample_internal (GstAppSrc * appsrc, GstSample * sample)
     GST_WARNING_OBJECT (appsrc, "received sample without caps");
   }
 
+  if (priv->handle_segment_change && priv->format == GST_FORMAT_TIME) {
+    GstSegment *segment = gst_sample_get_segment (sample);
+
+    if (segment->format != GST_FORMAT_TIME) {
+      GST_LOG_OBJECT (appsrc, "format %s is not supported",
+          gst_format_get_name (segment->format));
+      goto handle_buffer;
+    }
+
+    g_mutex_lock (&priv->mutex);
+    if (gst_segment_is_equal (&priv->last_segment, segment)) {
+      GST_LOG_OBJECT (appsrc, "segment wasn't changed");
+      g_mutex_unlock (&priv->mutex);
+      goto handle_buffer;
+    }
+
+    /* will be pushed to queue with next buffer/buffer-list */
+    gst_segment_copy_into (segment, &priv->last_segment);
+    priv->pending_custom_segment = TRUE;
+    g_mutex_unlock (&priv->mutex);
+  }
+
+handle_buffer:
+
   buffer = gst_sample_get_buffer (sample);
   if (buffer != NULL)
     return gst_app_src_push_buffer_full (appsrc, buffer, FALSE);