X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=gst%2Fgstbuffer.c;h=25c521360d1389cdf54c8486afed65526522c036;hb=94ba1cea88788fd3ad72fadcc2ceb7884ed6df50;hp=07d1e29999e48c8765d48d656e698150dd09f164;hpb=a5ab02733a614a258e0effcdeb91968f4795cb7b;p=platform%2Fupstream%2Fgstreamer.git

diff --git a/gst/gstbuffer.c b/gst/gstbuffer.c
index 07d1e29..25c5213 100644
--- a/gst/gstbuffer.c
+++ b/gst/gstbuffer.c
@@ -22,6 +22,7 @@
 
 /**
  * SECTION:gstbuffer
+ * @title: GstBuffer
  * @short_description: Data-passing buffer type
  * @see_also: #GstPad, #GstMiniObject, #GstMemory, #GstMeta, #GstBufferPool
  *
@@ -33,7 +34,7 @@
  * created one will typically allocate memory for it and add it to the buffer.
  * The following example creates a buffer that can hold a given video frame
  * with a given width, height and bits per plane.
- * |[
+ * |[<!-- language="C" -->
  *   GstBuffer *buffer;
  *   GstMemory *memory;
  *   gint size, width, height, bpp;
@@ -104,6 +105,16 @@
  * the refcount drops to 0, any memory and metadata pointed to by the buffer is
  * unreffed as well. Buffers allocated from a #GstBufferPool will be returned to
  * the pool when the refcount drops to 0.
+ *
+ * The #GstParentBufferMeta is a meta which can be attached to a #GstBuffer
+ * to hold a reference to another buffer that is only released when the child
+ * #GstBuffer is released.
+ *
+ * Typically, #GstParentBufferMeta is used when the child buffer is directly
+ * using the #GstMemory of the parent buffer, and wants to prevent the parent
+ * buffer from being returned to a buffer pool until the #GstMemory is available
+ * for re-use. (Since: 1.6)
+ *
  */
 #include "gst_private.h"
 
@@ -122,14 +133,9 @@
 
 GType _gst_buffer_type = 0;
 
-typedef struct _GstMetaItem GstMetaItem;
-
-struct _GstMetaItem
-{
-  GstMetaItem *next;
-  GstMeta meta;
-};
-#define ITEM_SIZE(info) ((info)->size + sizeof (GstMetaItem))
+/* info->size will be sizeof(FooMeta) which contains a GstMeta at the beginning
+ * too, and then there is again a GstMeta in GstMetaItem, so subtract one. */
+#define ITEM_SIZE(info) ((info)->size + sizeof (GstMetaItem) - sizeof (GstMeta))
 
 #define GST_BUFFER_MEM_MAX         16
 
@@ -139,6 +145,7 @@ struct _GstMetaItem
 #define GST_BUFFER_MEM_PTR(b,i)    (((GstBufferImpl *)(b))->mem[i])
 #define GST_BUFFER_BUFMEM(b)       (((GstBufferImpl *)(b))->bufmem)
 #define GST_BUFFER_META(b)         (((GstBufferImpl *)(b))->item)
+#define GST_BUFFER_TAIL_META(b)    (((GstBufferImpl *)(b))->tail_item)
 
 typedef struct
 {
@@ -156,8 +163,41 @@ typedef struct
   /* FIXME, make metadata allocation more efficient by using part of the
    * GstBufferImpl */
   GstMetaItem *item;
+  GstMetaItem *tail_item;
 } GstBufferImpl;
 
+static gint64 meta_seq;         /* 0 *//* ATOMIC */
+
+/* TODO: use GLib's once https://gitlab.gnome.org/GNOME/glib/issues/1076 lands */
+#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
+static inline gint64
+gst_atomic_int64_inc (volatile gint64 * atomic)
+{
+  return __sync_fetch_and_add (atomic, 1);
+}
+#elif defined (G_PLATFORM_WIN32)
+#include <windows.h>
+static inline gint64
+gst_atomic_int64_inc (volatile gint64 * atomic)
+{
+  return InterlockedExchangeAdd64 (atomic, 1);
+}
+#else
+#warning No 64-bit atomic int defined for this platform/toolchain!
+#define NO_64BIT_ATOMIC_INT_FOR_PLATFORM
+G_LOCK_DEFINE_STATIC (meta_seq);
+static inline gint64
+gst_atomic_int64_inc (volatile gint64 * atomic)
+{
+  gint64 ret;
+
+  G_LOCK (meta_seq);
+  ret = *atomic++;
+  G_UNLOCK (meta_seq);
+
+  return ret;
+}
+#endif
 
 static gboolean
 _is_span (GstMemory ** mem, gsize len, gsize * poffset, GstMemory ** parent)
@@ -226,13 +266,25 @@ _get_merged_memory (GstBuffer * buffer, guint idx, guint length)
       guint8 *ptr;
 
       result = gst_allocator_alloc (NULL, size, NULL);
-      gst_memory_map (result, &dinfo, GST_MAP_WRITE);
+      if (result == NULL || !gst_memory_map (result, &dinfo, GST_MAP_WRITE)) {
+        GST_CAT_ERROR (GST_CAT_BUFFER, "Failed to map memory writable");
+        if (result)
+          gst_memory_unref (result);
+        return NULL;
+      }
 
       ptr = dinfo.data;
       left = size;
 
       for (i = idx; i < (idx + length) && left > 0; i++) {
-        gst_memory_map (mem[i], &sinfo, GST_MAP_READ);
+        if (!gst_memory_map (mem[i], &sinfo, GST_MAP_READ)) {
+          GST_CAT_ERROR (GST_CAT_BUFFER,
+              "buffer %p, idx %u, length %u failed to map readable", buffer,
+              idx, length);
+          gst_memory_unmap (result, &dinfo);
+          gst_memory_unref (result);
+          return NULL;
+        }
         tocopy = MIN (sinfo.size, left);
         GST_CAT_DEBUG (GST_CAT_PERFORMANCE,
             "memcpy %" G_GSIZE_FORMAT " bytes for merge %p from memory %p",
@@ -265,11 +317,15 @@ _replace_memory (GstBuffer * buffer, guint len, guint idx, guint length,
     GstMemory *old = GST_BUFFER_MEM_PTR (buffer, i);
 
     gst_memory_unlock (old, GST_LOCK_FLAG_EXCLUSIVE);
+    gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (old),
+        GST_MINI_OBJECT_CAST (buffer));
     gst_memory_unref (old);
   }
 
   if (mem != NULL) {
     /* replace with single memory */
+    gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (mem),
+        GST_MINI_OBJECT_CAST (buffer));
     gst_memory_lock (mem, GST_LOCK_FLAG_EXCLUSIVE);
     GST_BUFFER_MEM_PTR (buffer, idx) = mem;
     idx++;
@@ -284,13 +340,111 @@ _replace_memory (GstBuffer * buffer, guint len, guint idx, guint length,
   GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_TAG_MEMORY);
 }
 
+/**
+ * gst_buffer_get_flags:
+ * @buffer: a #GstBuffer
+ *
+ * Get the #GstBufferFlags flags set on this buffer.
+ *
+ * Returns: the flags set on this buffer.
+ *
+ * Since: 1.10
+ */
+GstBufferFlags
+gst_buffer_get_flags (GstBuffer * buffer)
+{
+  return (GstBufferFlags) GST_BUFFER_FLAGS (buffer);
+}
+
+/**
+ * gst_buffer_flag_is_set:
+ * @buffer: a #GstBuffer
+ * @flags: the #GstBufferFlags flag to check.
+ *
+ * Gives the status of a specific flag on a buffer.
+ *
+ * Returns: %TRUE if all flags in @flags are found on @buffer.
+ *
+ * Since: 1.10
+ */
+gboolean
+gst_buffer_has_flags (GstBuffer * buffer, GstBufferFlags flags)
+{
+  return GST_BUFFER_FLAG_IS_SET (buffer, flags);
+}
+
+/**
+ * gst_buffer_set_flags:
+ * @buffer: a #GstBuffer
+ * @flags: the #GstBufferFlags to set.
+ *
+ * Sets one or more buffer flags on a buffer.
+ *
+ * Returns: %TRUE if @flags were successfully set on buffer.
+ *
+ * Since: 1.10
+ */
+gboolean
+gst_buffer_set_flags (GstBuffer * buffer, GstBufferFlags flags)
+{
+  GST_BUFFER_FLAG_SET (buffer, flags);
+  return TRUE;
+}
+
+/**
+ * gst_buffer_unset_flags:
+ * @buffer: a #GstBuffer
+ * @flags: the #GstBufferFlags to clear
+ *
+ * Clears one or more buffer flags.
+ *
+ * Returns: true if @flags is successfully cleared from buffer.
+ *
+ * Since: 1.10
+ */
+gboolean
+gst_buffer_unset_flags (GstBuffer * buffer, GstBufferFlags flags)
+{
+  GST_BUFFER_FLAG_UNSET (buffer, flags);
+  return TRUE;
+}
+
+
+
+/* transfer full for return and transfer none for @mem */
+static inline GstMemory *
+_memory_get_exclusive_reference (GstMemory * mem)
+{
+  GstMemory *ret = NULL;
+
+  if (gst_memory_lock (mem, GST_LOCK_FLAG_EXCLUSIVE)) {
+    ret = gst_memory_ref (mem);
+  } else {
+    /* we cannot take another exclusive lock as the memory is already
+     * locked WRITE + EXCLUSIVE according to part-miniobject.txt */
+    ret = gst_memory_copy (mem, 0, -1);
+
+    if (ret) {
+      if (!gst_memory_lock (ret, GST_LOCK_FLAG_EXCLUSIVE)) {
+        gst_memory_unref (ret);
+        ret = NULL;
+      }
+    }
+  }
+
+  if (!ret)
+    GST_CAT_WARNING (GST_CAT_BUFFER, "Failed to acquire an exclusive lock for "
+        "memory %p", mem);
+
+  return ret;
+}
+
 static inline void
-_memory_add (GstBuffer * buffer, gint idx, GstMemory * mem, gboolean lock)
+_memory_add (GstBuffer * buffer, gint idx, GstMemory * mem)
 {
   guint i, len = GST_BUFFER_MEM_LEN (buffer);
 
-  GST_CAT_LOG (GST_CAT_BUFFER, "buffer %p, idx %d, mem %p, lock %d", buffer,
-      idx, mem, lock);
+  GST_CAT_LOG (GST_CAT_BUFFER, "buffer %p, idx %d, mem %p", buffer, idx, mem);
 
   if (G_UNLIKELY (len >= GST_BUFFER_MEM_MAX)) {
     /* too many buffer, span them. */
@@ -312,10 +466,10 @@ _memory_add (GstBuffer * buffer, gint idx, GstMemory * mem, gboolean lock)
     GST_BUFFER_MEM_PTR (buffer, i) = GST_BUFFER_MEM_PTR (buffer, i - 1);
   }
   /* and insert the new buffer */
-  if (lock)
-    gst_memory_lock (mem, GST_LOCK_FLAG_EXCLUSIVE);
   GST_BUFFER_MEM_PTR (buffer, idx) = mem;
   GST_BUFFER_MEM_LEN (buffer) = len + 1;
+  gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (mem),
+      GST_MINI_OBJECT_CAST (buffer));
 
   GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_TAG_MEMORY);
 }
@@ -326,6 +480,11 @@ void
 _priv_gst_buffer_initialize (void)
 {
   _gst_buffer_type = gst_buffer_get_type ();
+
+#ifdef NO_64BIT_ATOMIC_INT_FOR_PLATFORM
+  GST_CAT_WARNING (GST_CAT_PERFORMANCE,
+      "No 64-bit atomic int defined for this platform/toolchain!");
+#endif
 }
 
 /**
@@ -451,17 +610,22 @@ gst_buffer_copy_into (GstBuffer * dest, GstBuffer * src,
         if (tocopy < bsize && !deep && !GST_MEMORY_IS_NO_SHARE (mem)) {
           /* we need to clip something */
           newmem = gst_memory_share (mem, skip, tocopy);
-          if (newmem)
+          if (newmem) {
+            gst_memory_lock (newmem, GST_LOCK_FLAG_EXCLUSIVE);
             skip = 0;
+          }
         }
 
         if (deep || GST_MEMORY_IS_NO_SHARE (mem) || (!newmem && tocopy < bsize)) {
           /* deep copy or we're not allowed to share this memory
            * between buffers, always copy then */
           newmem = gst_memory_copy (mem, skip, tocopy);
-          skip = 0;
+          if (newmem) {
+            gst_memory_lock (newmem, GST_LOCK_FLAG_EXCLUSIVE);
+            skip = 0;
+          }
         } else if (!newmem) {
-          newmem = gst_memory_ref (mem);
+          newmem = _memory_get_exclusive_reference (mem);
         }
 
         if (!newmem) {
@@ -469,7 +633,7 @@ gst_buffer_copy_into (GstBuffer * dest, GstBuffer * src,
           return FALSE;
         }
 
-        _memory_add (dest, -1, newmem, TRUE);
+        _memory_add (dest, -1, newmem);
         left -= tocopy;
       }
     }
@@ -487,11 +651,24 @@ gst_buffer_copy_into (GstBuffer * dest, GstBuffer * src,
   }
 
   if (flags & GST_BUFFER_COPY_META) {
+    /* NOTE: GstGLSyncMeta copying relies on the meta
+     *       being copied now, after the buffer data,
+     *       so this has to happen last */
     for (walk = GST_BUFFER_META (src); walk; walk = walk->next) {
       GstMeta *meta = &walk->meta;
       const GstMetaInfo *info = meta->info;
 
-      if (info->transform_func) {
+      /* Don't copy memory metas if we only copied part of the buffer, didn't
+       * copy memories or merged memories. In all these cases the memory
+       * structure has changed and the memory meta becomes meaningless.
+       */
+      if ((region || !(flags & GST_BUFFER_COPY_MEMORY)
+              || (flags & GST_BUFFER_COPY_MERGE))
+          && gst_meta_api_type_has_tag (info->api, _gst_meta_tag_memory)) {
+        GST_CAT_DEBUG (GST_CAT_BUFFER,
+            "don't copy memory meta %p of API type %s", meta,
+            g_type_name (info->api));
+      } else if (info->transform_func) {
         GstMetaTransformCopy copy_data;
 
         copy_data.region = region;
@@ -546,6 +723,8 @@ _gst_buffer_copy (const GstBuffer * buffer)
  * copy of the data the source buffer contains.
  *
  * Returns: (transfer full): a new copy of @buf.
+ *
+ * Since: 1.6
  */
 GstBuffer *
 gst_buffer_copy_deep (const GstBuffer * buffer)
@@ -607,6 +786,8 @@ _gst_buffer_free (GstBuffer * buffer)
   len = GST_BUFFER_MEM_LEN (buffer);
   for (i = 0; i < len; i++) {
     gst_memory_unlock (GST_BUFFER_MEM_PTR (buffer, i), GST_LOCK_FLAG_EXCLUSIVE);
+    gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (GST_BUFFER_MEM_PTR
+            (buffer, i)), GST_MINI_OBJECT_CAST (buffer));
     gst_memory_unref (GST_BUFFER_MEM_PTR (buffer, i));
   }
 
@@ -706,8 +887,10 @@ gst_buffer_new_allocate (GstAllocator * allocator, gsize size,
 
   newbuf = gst_buffer_new ();
 
-  if (mem != NULL)
-    _memory_add (newbuf, -1, mem, TRUE);
+  if (mem != NULL) {
+    gst_memory_lock (mem, GST_LOCK_FLAG_EXCLUSIVE);
+    _memory_add (newbuf, -1, mem);
+  }
 
   GST_CAT_LOG (GST_CAT_BUFFER,
       "new buffer %p of size %" G_GSIZE_FORMAT " from allocator %p", newbuf,
@@ -801,7 +984,8 @@ gst_buffer_new_wrapped_full (GstMemoryFlags flags, gpointer data,
   mem =
       gst_memory_new_wrapped (flags, data, maxsize, offset, size, user_data,
       notify);
-  _memory_add (newbuf, -1, mem, TRUE);
+  gst_memory_lock (mem, GST_LOCK_FLAG_EXCLUSIVE);
+  _memory_add (newbuf, -1, mem);
   GST_BUFFER_FLAG_UNSET (newbuf, GST_BUFFER_FLAG_TAG_MEMORY);
 
   return newbuf;
@@ -826,13 +1010,40 @@ gst_buffer_new_wrapped (gpointer data, gsize size)
 }
 
 /**
+ * gst_buffer_new_wrapped_bytes:
+ * @bytes: (transfer none): a #GBytes to wrap
+ *
+ * Creates a new #GstBuffer that wraps the given @bytes. The data inside
+ * @bytes cannot be %NULL and the resulting buffer will be marked as read only.
+ *
+ * MT safe.
+ *
+ * Returns: (transfer full): a new #GstBuffer wrapping @bytes
+ *
+ * Since: 1.16
+ */
+GstBuffer *
+gst_buffer_new_wrapped_bytes (GBytes * bytes)
+{
+  guint8 *bytes_data;
+  gsize size;
+
+  g_return_val_if_fail (bytes != NULL, NULL);
+  bytes_data = (guint8 *) g_bytes_get_data (bytes, &size);
+  g_return_val_if_fail (bytes_data != NULL, NULL);
+
+  return gst_buffer_new_wrapped_full (GST_MEMORY_FLAG_READONLY, bytes_data,
+      size, 0, size, g_bytes_ref (bytes), (GDestroyNotify) g_bytes_unref);
+}
+
+/**
  * gst_buffer_n_memory:
  * @buffer: a #GstBuffer.
  *
  * Get the amount of memory blocks that this buffer has. This amount is never
  * larger than what gst_buffer_get_max_memory() returns.
  *
- * Returns: (transfer full): the amount of memory block in this buffer.
+ * Returns: the number of memory blocks this buffer is made of.
  */
 guint
 gst_buffer_n_memory (GstBuffer * buffer)
@@ -892,13 +1103,18 @@ gst_buffer_append_memory (GstBuffer * buffer, GstMemory * mem)
 void
 gst_buffer_insert_memory (GstBuffer * buffer, gint idx, GstMemory * mem)
 {
+  GstMemory *tmp;
+
   g_return_if_fail (GST_IS_BUFFER (buffer));
   g_return_if_fail (gst_buffer_is_writable (buffer));
   g_return_if_fail (mem != NULL);
   g_return_if_fail (idx == -1 ||
       (idx >= 0 && idx <= GST_BUFFER_MEM_LEN (buffer)));
 
-  _memory_add (buffer, idx, mem, TRUE);
+  tmp = _memory_get_exclusive_reference (mem);
+  g_return_if_fail (tmp != NULL);
+  gst_memory_unref (mem);
+  _memory_add (buffer, idx, tmp);
 }
 
 static GstMemory *
@@ -913,10 +1129,14 @@ _get_mapped (GstBuffer * buffer, guint idx, GstMapInfo * info,
 
   if (mapped != mem) {
     /* memory changed, lock new memory */
+    gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (mapped),
+        GST_MINI_OBJECT_CAST (buffer));
     gst_memory_lock (mapped, GST_LOCK_FLAG_EXCLUSIVE);
     GST_BUFFER_MEM_PTR (buffer, idx) = mapped;
     /* unlock old memory */
     gst_memory_unlock (mem, GST_LOCK_FLAG_EXCLUSIVE);
+    gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (mem),
+        GST_MINI_OBJECT_CAST (buffer));
     GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_TAG_MEMORY);
   }
   gst_memory_unref (mem);
@@ -933,7 +1153,7 @@ _get_mapped (GstBuffer * buffer, guint idx, GstMapInfo * info,
  * the memory block in @buffer is removed, replaced or merged, typically with
  * any call that modifies the memory in @buffer.
  *
- * Returns: (transfer none): the #GstMemory at @idx.
+ * Returns: (transfer none) (nullable): the #GstMemory at @idx.
  */
 GstMemory *
 gst_buffer_peek_memory (GstBuffer * buffer, guint idx)
@@ -954,7 +1174,7 @@ gst_buffer_peek_memory (GstBuffer * buffer, guint idx)
  *
  * Get the memory block at index @idx in @buffer.
  *
- * Returns: (transfer full): a #GstMemory that contains the data of the
+ * Returns: (transfer full) (nullable): a #GstMemory that contains the data of the
  * memory block at @idx. Use gst_memory_unref () after usage.
  */
 GstMemory *
@@ -970,7 +1190,7 @@ gst_buffer_get_memory (GstBuffer * buffer, guint idx)
  * Get all the memory block in @buffer. The memory blocks will be merged
  * into one large #GstMemory.
  *
- * Returns: (transfer full): a #GstMemory that contains the merged memory.
+ * Returns: (transfer full) (nullable): a #GstMemory that contains the merged memory.
  * Use gst_memory_unref () after usage.
  */
 GstMemory *
@@ -990,7 +1210,7 @@ gst_buffer_get_all_memory (GstBuffer * buffer)
  *
  * If @length is -1, all memory starting from @idx is merged.
  *
- * Returns: (transfer full): a #GstMemory that contains the merged data of @length
+ * Returns: (transfer full) (nullable): a #GstMemory that contains the merged data of @length
  *    blocks starting at @idx. Use gst_memory_unref () after usage.
  */
 GstMemory *
@@ -1486,9 +1706,13 @@ gst_buffer_resize_range (GstBuffer * buffer, guint idx, gint length,
         if (newmem == NULL)
           return FALSE;
 
+        gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (newmem),
+            GST_MINI_OBJECT_CAST (buffer));
         gst_memory_lock (newmem, GST_LOCK_FLAG_EXCLUSIVE);
         GST_BUFFER_MEM_PTR (buffer, i) = newmem;
         gst_memory_unlock (mem, GST_LOCK_FLAG_EXCLUSIVE);
+        gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (mem),
+            GST_MINI_OBJECT_CAST (buffer));
         gst_memory_unref (mem);
 
         GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_TAG_MEMORY);
@@ -1707,7 +1931,8 @@ gst_buffer_fill (GstBuffer * buffer, gsize offset, gconstpointer src,
  * gst_buffer_extract:
  * @buffer: a #GstBuffer.
  * @offset: the offset to extract
- * @dest: the destination address
+ * @dest: (out caller-allocates) (array length=size) (element-type guint8):
+ *     the destination address
  * @size: the size to extract
  *
  * Copy @size bytes starting from @offset in @buffer to @dest.
@@ -1858,7 +2083,7 @@ gst_buffer_memset (GstBuffer * buffer, gsize offset, guint8 val, gsize size)
  * gst_buffer_copy_region:
  * @parent: a #GstBuffer.
  * @flags: the #GstBufferCopyFlags
- * @offset: the offset into parent #GstBuffer at which the new sub-buffer 
+ * @offset: the offset into parent #GstBuffer at which the new sub-buffer
  *          begins.
  * @size: the size of the new #GstBuffer sub-buffer, in bytes. If -1, all
  *        data is copied.
@@ -1866,7 +2091,7 @@ gst_buffer_memset (GstBuffer * buffer, gsize offset, guint8 val, gsize size)
  * Creates a sub-buffer from @parent at @offset and @size.
  * This sub-buffer uses the actual memory space of the parent buffer.
  * This function will copy the offset and timestamp fields when the
- * offset is 0. If not, they will be set to #GST_CLOCK_TIME_NONE and 
+ * offset is 0. If not, they will be set to #GST_CLOCK_TIME_NONE and
  * #GST_BUFFER_OFFSET_NONE.
  * If @offset equals 0 and @size equals the total size of @buffer, the
  * duration and offset end fields are also copied. If not they will be set
@@ -1947,8 +2172,10 @@ gst_buffer_append_region (GstBuffer * buf1, GstBuffer * buf2, gssize offset,
     GstMemory *mem;
 
     mem = GST_BUFFER_MEM_PTR (buf2, i);
+    gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (mem),
+        GST_MINI_OBJECT_CAST (buf2));
     GST_BUFFER_MEM_PTR (buf2, i) = NULL;
-    _memory_add (buf1, -1, mem, FALSE);
+    _memory_add (buf1, -1, mem);
   }
 
   GST_BUFFER_MEM_LEN (buf2) = 0;
@@ -1993,6 +2220,28 @@ gst_buffer_get_meta (GstBuffer * buffer, GType api)
 }
 
 /**
+ * gst_buffer_get_n_meta:
+ * @buffer: a #GstBuffer
+ * @api_type: the #GType of an API
+ *
+ * Returns: number of metas of type @api_type on @buffer.
+ *
+ * Since: 1.14
+ */
+guint
+gst_buffer_get_n_meta (GstBuffer * buffer, GType api_type)
+{
+  gpointer state = NULL;
+  GstMeta *meta;
+  guint n = 0;
+
+  while ((meta = gst_buffer_iterate_meta_filtered (buffer, &state, api_type)))
+    ++n;
+
+  return n;
+}
+
+/**
  * gst_buffer_add_meta:
  * @buffer: a #GstBuffer
  * @info: a #GstMetaInfo
@@ -2000,7 +2249,7 @@ gst_buffer_get_meta (GstBuffer * buffer, GType api)
  *
  * Add metadata for @info to @buffer using the parameters in @params.
  *
- * Returns: (transfer none): the metadata for the api in @info on @buffer.
+ * Returns: (transfer none) (nullable): the metadata for the api in @info on @buffer.
  */
 GstMeta *
 gst_buffer_add_meta (GstBuffer * buffer, const GstMetaInfo * info,
@@ -2016,11 +2265,17 @@ gst_buffer_add_meta (GstBuffer * buffer, const GstMetaInfo * info,
 
   /* create a new slice */
   size = ITEM_SIZE (info);
-  item = g_slice_alloc (size);
+  /* We warn in gst_meta_register() about metas without
+   * init function but let's play safe here and prevent
+   * uninitialized memory
+   */
+  if (!info->init_func)
+    item = g_slice_alloc0 (size);
+  else
+    item = g_slice_alloc (size);
   result = &item->meta;
   result->info = info;
   result->flags = GST_META_FLAG_NONE;
-
   GST_CAT_DEBUG (GST_CAT_BUFFER,
       "alloc metadata %p (%s) of size %" G_GSIZE_FORMAT, result,
       g_type_name (info->type), info->size);
@@ -2030,9 +2285,16 @@ gst_buffer_add_meta (GstBuffer * buffer, const GstMetaInfo * info,
     if (!info->init_func (result, params, buffer))
       goto init_failed;
 
-  /* and add to the list of metadata */
-  item->next = GST_BUFFER_META (buffer);
-  GST_BUFFER_META (buffer) = item;
+  item->seq_num = gst_atomic_int64_inc (&meta_seq);
+  item->next = NULL;
+
+  if (!GST_BUFFER_META (buffer)) {
+    GST_BUFFER_META (buffer) = item;
+    GST_BUFFER_TAIL_META (buffer) = item;
+  } else {
+    GST_BUFFER_TAIL_META (buffer)->next = item;
+    GST_BUFFER_TAIL_META (buffer) = item;
+  }
 
   return result;
 
@@ -2072,10 +2334,18 @@ gst_buffer_remove_meta (GstBuffer * buffer, GstMeta * meta)
       const GstMetaInfo *info = meta->info;
 
       /* remove from list */
+      if (GST_BUFFER_TAIL_META (buffer) == walk) {
+        if (prev != walk)
+          GST_BUFFER_TAIL_META (buffer) = prev;
+        else
+          GST_BUFFER_TAIL_META (buffer) = NULL;
+      }
+
       if (GST_BUFFER_META (buffer) == walk)
         GST_BUFFER_META (buffer) = walk->next;
       else
         prev->next = walk->next;
+
       /* call free_func if any */
       if (info->free_func)
         info->free_func (m, buffer);
@@ -2090,9 +2360,9 @@ gst_buffer_remove_meta (GstBuffer * buffer, GstMeta * meta)
 }
 
 /**
- * gst_buffer_iterate_meta:
+ * gst_buffer_iterate_meta: (skip)
  * @buffer: a #GstBuffer
- * @state: an opaque state pointer
+ * @state: (out caller-allocates): an opaque state pointer
  *
  * Retrieve the next #GstMeta after @current. If @state points
  * to %NULL, the first metadata is returned.
@@ -2125,6 +2395,49 @@ gst_buffer_iterate_meta (GstBuffer * buffer, gpointer * state)
 }
 
 /**
+ * gst_buffer_iterate_meta_filtered: (skip)
+ * @buffer: a #GstBuffer
+ * @state: (out caller-allocates): an opaque state pointer
+ * @meta_api_type: only return #GstMeta of this type
+ *
+ * Retrieve the next #GstMeta of type @meta_api_type after the current one
+ * according to @state. If @state points to %NULL, the first metadata of
+ * type @meta_api_type is returned.
+ *
+ * @state will be updated with an opaque state pointer
+ *
+ * Returns: (transfer none) (nullable): The next #GstMeta of type
+ * @meta_api_type or %NULL when there are no more items.
+ *
+ * Since: 1.12
+ */
+GstMeta *
+gst_buffer_iterate_meta_filtered (GstBuffer * buffer, gpointer * state,
+    GType meta_api_type)
+{
+  GstMetaItem **meta;
+
+  g_return_val_if_fail (buffer != NULL, NULL);
+  g_return_val_if_fail (state != NULL, NULL);
+
+  meta = (GstMetaItem **) state;
+  if (*meta == NULL)
+    /* state NULL, move to first item */
+    *meta = GST_BUFFER_META (buffer);
+  else
+    /* state !NULL, move to next item in list */
+    *meta = (*meta)->next;
+
+  while (*meta != NULL && (*meta)->meta.info->api != meta_api_type)
+    *meta = (*meta)->next;
+
+  if (*meta)
+    return &(*meta)->meta;
+  else
+    return NULL;
+}
+
+/**
  * gst_buffer_foreach_meta:
  * @buffer: a #GstBuffer
  * @func: (scope call): a #GstBufferForeachMetaFunc to call
@@ -2168,9 +2481,16 @@ gst_buffer_foreach_meta (GstBuffer * buffer, GstBufferForeachMetaFunc func,
       g_return_val_if_fail (!GST_META_FLAG_IS_SET (m, GST_META_FLAG_LOCKED),
           FALSE);
 
+      if (GST_BUFFER_TAIL_META (buffer) == walk) {
+        if (prev != walk)
+          GST_BUFFER_TAIL_META (buffer) = prev;
+        else
+          GST_BUFFER_TAIL_META (buffer) = NULL;
+      }
+
       /* remove from list */
       if (GST_BUFFER_META (buffer) == walk)
-        GST_BUFFER_META (buffer) = next;
+        prev = GST_BUFFER_META (buffer) = next;
       else
         prev->next = next;
 
@@ -2180,6 +2500,8 @@ gst_buffer_foreach_meta (GstBuffer * buffer, GstBufferForeachMetaFunc func,
 
       /* and free the slice */
       g_slice_free1 (ITEM_SIZE (info), walk);
+    } else {
+      prev = walk;
     }
     if (!res)
       break;
@@ -2193,11 +2515,11 @@ gst_buffer_foreach_meta (GstBuffer * buffer, GstBufferForeachMetaFunc func,
  * @offset: the offset to extract
  * @size: the size to extract
  * @dest: (array length=dest_size) (element-type guint8) (out): A pointer where
- *  the destination array will be written.
+ *  the destination array will be written. Might be %NULL if the size is 0.
  * @dest_size: (out): A location where the size of @dest can be written
  *
- * Extracts a copy of at most @size bytes the data at @offset into a #GBytes.
- * @dest must be freed using g_free() when done.
+ * Extracts a copy of at most @size bytes the data at @offset into
+ * newly-allocated memory. @dest must be freed using g_free() when done.
  *
  * Since: 1.0.10
  */
@@ -2206,11 +2528,313 @@ void
 gst_buffer_extract_dup (GstBuffer * buffer, gsize offset, gsize size,
     gpointer * dest, gsize * dest_size)
 {
-  gsize real_size;
+  gsize real_size, alloc_size;
 
   real_size = gst_buffer_get_size (buffer);
 
-  *dest = g_malloc (MIN (real_size - offset, size));
+  alloc_size = MIN (real_size - offset, size);
+  if (alloc_size == 0) {
+    *dest = NULL;
+    *dest_size = 0;
+  } else {
+    *dest = g_malloc (alloc_size);
+    *dest_size = gst_buffer_extract (buffer, offset, *dest, size);
+  }
+}
+
+GST_DEBUG_CATEGORY_STATIC (gst_parent_buffer_meta_debug);
+
+/**
+ * gst_buffer_add_parent_buffer_meta:
+ * @buffer: (transfer none): a #GstBuffer
+ * @ref: (transfer none): a #GstBuffer to ref
+ *
+ * Add a #GstParentBufferMeta to @buffer that holds a reference on
+ * @ref until the buffer is freed.
+ *
+ * Returns: (transfer none) (nullable): The #GstParentBufferMeta that was added to the buffer
+ *
+ * Since: 1.6
+ */
+GstParentBufferMeta *
+gst_buffer_add_parent_buffer_meta (GstBuffer * buffer, GstBuffer * ref)
+{
+  GstParentBufferMeta *meta;
+
+  g_return_val_if_fail (GST_IS_BUFFER (ref), NULL);
+
+  meta =
+      (GstParentBufferMeta *) gst_buffer_add_meta (buffer,
+      GST_PARENT_BUFFER_META_INFO, NULL);
+
+  if (!meta)
+    return NULL;
+
+  meta->buffer = gst_buffer_ref (ref);
+
+  return meta;
+}
+
+static gboolean
+_gst_parent_buffer_meta_transform (GstBuffer * dest, GstMeta * meta,
+    GstBuffer * buffer, GQuark type, gpointer data)
+{
+  GstParentBufferMeta *dmeta, *smeta;
+
+  smeta = (GstParentBufferMeta *) meta;
+
+  if (GST_META_TRANSFORM_IS_COPY (type)) {
+    /* copy over the reference to the parent buffer.
+     * Usually, this meta means we need to keep the parent buffer
+     * alive because one of the child memories is in use, which
+     * might not be the case if memory is deep copied or sub-regioned,
+     * but we can't tell, so keep the meta */
+    dmeta = gst_buffer_add_parent_buffer_meta (dest, smeta->buffer);
+    if (!dmeta)
+      return FALSE;
+
+    GST_CAT_DEBUG (gst_parent_buffer_meta_debug,
+        "copy buffer reference metadata");
+  } else {
+    /* return FALSE, if transform type is not supported */
+    return FALSE;
+  }
+  return TRUE;
+}
+
+static void
+_gst_parent_buffer_meta_free (GstParentBufferMeta * parent_meta,
+    GstBuffer * buffer)
+{
+  GST_CAT_DEBUG (gst_parent_buffer_meta_debug,
+      "Dropping reference on buffer %p", parent_meta->buffer);
+  gst_buffer_unref (parent_meta->buffer);
+}
+
+static gboolean
+_gst_parent_buffer_meta_init (GstParentBufferMeta * parent_meta,
+    gpointer params, GstBuffer * buffer)
+{
+  static volatile gsize _init;
+
+  if (g_once_init_enter (&_init)) {
+    GST_DEBUG_CATEGORY_INIT (gst_parent_buffer_meta_debug, "parentbuffermeta",
+        0, "parentbuffermeta");
+    g_once_init_leave (&_init, 1);
+  }
+
+  parent_meta->buffer = NULL;
+
+  return TRUE;
+}
+
+GType
+gst_parent_buffer_meta_api_get_type (void)
+{
+  static volatile GType type = 0;
+  static const gchar *tags[] = { NULL };
+
+  if (g_once_init_enter (&type)) {
+    GType _type = gst_meta_api_type_register ("GstParentBufferMetaAPI", tags);
+    g_once_init_leave (&type, _type);
+  }
+
+  return type;
+}
+
+/**
+ * gst_parent_buffer_meta_get_info:
+ *
+ * Get the global #GstMetaInfo describing  the #GstParentBufferMeta meta.
+ *
+ * Returns: (transfer none): The #GstMetaInfo
+ *
+ * Since: 1.6
+ */
+const GstMetaInfo *
+gst_parent_buffer_meta_get_info (void)
+{
+  static const GstMetaInfo *meta_info = NULL;
+
+  if (g_once_init_enter ((GstMetaInfo **) & meta_info)) {
+    const GstMetaInfo *meta =
+        gst_meta_register (gst_parent_buffer_meta_api_get_type (),
+        "GstParentBufferMeta",
+        sizeof (GstParentBufferMeta),
+        (GstMetaInitFunction) _gst_parent_buffer_meta_init,
+        (GstMetaFreeFunction) _gst_parent_buffer_meta_free,
+        _gst_parent_buffer_meta_transform);
+    g_once_init_leave ((GstMetaInfo **) & meta_info, (GstMetaInfo *) meta);
+  }
+
+  return meta_info;
+}
+
+GST_DEBUG_CATEGORY_STATIC (gst_reference_timestamp_meta_debug);
+
+/**
+ * gst_buffer_add_reference_timestamp_meta:
+ * @buffer: (transfer none): a #GstBuffer
+ * @reference: (transfer none): identifier for the timestamp reference.
+ * @timestamp: timestamp
+ * @duration: duration, or %GST_CLOCK_TIME_NONE
+ *
+ * Add a #GstReferenceTimestampMeta to @buffer that holds a @timestamp and
+ * optionally @duration based on a specific timestamp @reference. See the
+ * documentation of #GstReferenceTimestampMeta for details.
+ *
+ * Returns: (transfer none) (nullable): The #GstReferenceTimestampMeta that was added to the buffer
+ *
+ * Since: 1.14
+ */
+GstReferenceTimestampMeta *
+gst_buffer_add_reference_timestamp_meta (GstBuffer * buffer,
+    GstCaps * reference, GstClockTime timestamp, GstClockTime duration)
+{
+  GstReferenceTimestampMeta *meta;
+
+  g_return_val_if_fail (GST_IS_CAPS (reference), NULL);
+  g_return_val_if_fail (timestamp != GST_CLOCK_TIME_NONE, NULL);
+
+  meta =
+      (GstReferenceTimestampMeta *) gst_buffer_add_meta (buffer,
+      GST_REFERENCE_TIMESTAMP_META_INFO, NULL);
+
+  if (!meta)
+    return NULL;
+
+  meta->reference = gst_caps_ref (reference);
+  meta->timestamp = timestamp;
+  meta->duration = duration;
+
+  return meta;
+}
+
+/**
+ * gst_buffer_get_reference_timestamp_meta:
+ * @buffer: a #GstBuffer
+ * @reference: (allow-none): a reference #GstCaps
+ *
+ * Find the first #GstReferenceTimestampMeta on @buffer that conforms to
+ * @reference. Conformance is tested by checking if the meta's reference is a
+ * subset of @reference.
+ *
+ * Buffers can contain multiple #GstReferenceTimestampMeta metadata items.
+ *
+ * Returns: (transfer none) (nullable): the #GstReferenceTimestampMeta or %NULL when there
+ * is no such metadata on @buffer.
+ *
+ * Since: 1.14
+ */
+GstReferenceTimestampMeta *
+gst_buffer_get_reference_timestamp_meta (GstBuffer * buffer,
+    GstCaps * reference)
+{
+  gpointer state = NULL;
+  GstMeta *meta;
+  const GstMetaInfo *info = GST_REFERENCE_TIMESTAMP_META_INFO;
+
+  while ((meta = gst_buffer_iterate_meta (buffer, &state))) {
+    if (meta->info->api == info->api) {
+      GstReferenceTimestampMeta *rmeta = (GstReferenceTimestampMeta *) meta;
+
+      if (!reference)
+        return rmeta;
+      if (gst_caps_is_subset (rmeta->reference, reference))
+        return rmeta;
+    }
+  }
+  return NULL;
+}
+
+static gboolean
+_gst_reference_timestamp_meta_transform (GstBuffer * dest, GstMeta * meta,
+    GstBuffer * buffer, GQuark type, gpointer data)
+{
+  GstReferenceTimestampMeta *dmeta, *smeta;
+
+  /* we copy over the reference timestamp meta, independent of transformation
+   * that happens. If it applied to the original buffer, it still applies to
+   * the new buffer as it refers to the time when the media was captured */
+  smeta = (GstReferenceTimestampMeta *) meta;
+  dmeta =
+      gst_buffer_add_reference_timestamp_meta (dest, smeta->reference,
+      smeta->timestamp, smeta->duration);
+  if (!dmeta)
+    return FALSE;
+
+  GST_CAT_DEBUG (gst_reference_timestamp_meta_debug,
+      "copy reference timestamp metadata from buffer %p to %p", buffer, dest);
+
+  return TRUE;
+}
+
+static void
+_gst_reference_timestamp_meta_free (GstReferenceTimestampMeta * meta,
+    GstBuffer * buffer)
+{
+  if (meta->reference)
+    gst_caps_unref (meta->reference);
+}
+
+static gboolean
+_gst_reference_timestamp_meta_init (GstReferenceTimestampMeta * meta,
+    gpointer params, GstBuffer * buffer)
+{
+  static volatile gsize _init;
+
+  if (g_once_init_enter (&_init)) {
+    GST_DEBUG_CATEGORY_INIT (gst_reference_timestamp_meta_debug,
+        "referencetimestampmeta", 0, "referencetimestampmeta");
+    g_once_init_leave (&_init, 1);
+  }
+
+  meta->reference = NULL;
+  meta->timestamp = GST_CLOCK_TIME_NONE;
+  meta->duration = GST_CLOCK_TIME_NONE;
+
+  return TRUE;
+}
+
+GType
+gst_reference_timestamp_meta_api_get_type (void)
+{
+  static volatile GType type = 0;
+  static const gchar *tags[] = { NULL };
+
+  if (g_once_init_enter (&type)) {
+    GType _type =
+        gst_meta_api_type_register ("GstReferenceTimestampMetaAPI", tags);
+    g_once_init_leave (&type, _type);
+  }
+
+  return type;
+}
+
+/**
+ * gst_reference_timestamp_meta_get_info:
+ *
+ * Get the global #GstMetaInfo describing  the #GstReferenceTimestampMeta meta.
+ *
+ * Returns: (transfer none): The #GstMetaInfo
+ *
+ * Since: 1.14
+ */
+const GstMetaInfo *
+gst_reference_timestamp_meta_get_info (void)
+{
+  static const GstMetaInfo *meta_info = NULL;
+
+  if (g_once_init_enter ((GstMetaInfo **) & meta_info)) {
+    const GstMetaInfo *meta =
+        gst_meta_register (gst_reference_timestamp_meta_api_get_type (),
+        "GstReferenceTimestampMeta",
+        sizeof (GstReferenceTimestampMeta),
+        (GstMetaInitFunction) _gst_reference_timestamp_meta_init,
+        (GstMetaFreeFunction) _gst_reference_timestamp_meta_free,
+        _gst_reference_timestamp_meta_transform);
+    g_once_init_leave ((GstMetaInfo **) & meta_info, (GstMetaInfo *) meta);
+  }
 
-  *dest_size = gst_buffer_extract (buffer, offset, *dest, size);
+  return meta_info;
 }