codecparsers: Add LCEVC metadata API

This new metadata API allows elements to attach LCEVC enhancement data to video
buffers. Usually, the video parser elements are charged to parse the LCEVC
enhancement data from SEI Nal units (Supplemental enhancement Information).
However, other elements such as demuxers can also use this API if the LCEVC
enhancement data of the video is stored in a separate stream in the container.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7330>

subprojects/gst-plugins-bad/gst-libs/gst/codecparsers/gstlcevcmeta.c

@@ -0,0 +1,230 @@
+/* GStreamer LCEVC meta
+ *  Copyright (C) <2024> V-Nova International Limited
+ *
+ * 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.
+ */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstlcevcmeta.h"
+
+/**
+ * SECTION:gstlcevcmeta
+ * @title: GstMeta for LCEVC
+ * @short_description: LCEVC related GstMeta
+ *
+ */
+
+#define GST_CAT_DEFAULT lcevcmeta_debug
+GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
+
+static gboolean
+gst_lcevc_meta_init (GstMeta * meta, gpointer params, GstBuffer * buffer)
+{
+  GstLcevcMeta *emeta = (GstLcevcMeta *) meta;
+
+  emeta->id = 0;
+  emeta->enhancement_data = NULL;
+
+  return TRUE;
+}
+
+static void
+gst_lcevc_meta_free (GstMeta * meta, GstBuffer * buffer)
+{
+  GstLcevcMeta *emeta = (GstLcevcMeta *) meta;
+
+  g_clear_pointer (&emeta->enhancement_data, gst_buffer_unref);
+}
+
+static gboolean
+gst_lcevc_meta_transform (GstBuffer * dest, GstMeta * meta,
+    GstBuffer * buffer, GQuark type, gpointer data)
+{
+  GstLcevcMeta *dmeta, *smeta;
+
+  smeta = (GstLcevcMeta *) meta;
+
+  if (GST_META_TRANSFORM_IS_COPY (type)) {
+    GstMetaTransformCopy *copy = data;
+
+    if (!copy->region) {
+      /* only copy if the complete data is copied as well */
+      dmeta = (GstLcevcMeta *) gst_buffer_add_meta (dest,
+          GST_LCEVC_META_INFO, NULL);
+
+      if (!dmeta)
+        return FALSE;
+
+      GST_TRACE ("copying lcevc metadata");
+      dmeta->id = smeta->id;
+
+      g_clear_pointer (&dmeta->enhancement_data, gst_buffer_unref);
+      dmeta->enhancement_data = gst_buffer_copy (smeta->enhancement_data);
+    }
+  } else {
+    /* return FALSE, if transform type is not supported */
+    return FALSE;
+  }
+  return TRUE;
+}
+
+
+/**
+ * gst_lcevc_meta_api_get_type:
+ *
+ * Gets the #GType of the LCEVC meta API.
+ *
+ * Returns: the #GType of the LCEVC meta API.
+ *
+ * Since: 1.26
+ */
+GType
+gst_lcevc_meta_api_get_type (void)
+{
+  static GType type = 0;
+  static const gchar *tags[] = { "video", NULL };
+
+  if (g_once_init_enter (&type)) {
+    GType _type = gst_meta_api_type_register ("GstLcevcMetaAPI", tags);
+    g_once_init_leave (&type, _type);
+  }
+  return type;
+}
+
+/**
+ * gst_lcevc_meta_get_info:
+ *
+ * Gets the #GstMetaInfo of the LCEVC meta.
+ *
+ * Returns: (transfer none) : the #GstLcevcMeta of the LCEVC meta.
+ *
+ * Since: 1.26
+ */
+const GstMetaInfo *
+gst_lcevc_meta_get_info (void)
+{
+  static const GstMetaInfo *lcevc_meta_info = NULL;
+
+  if (g_once_init_enter ((GstMetaInfo **) & lcevc_meta_info)) {
+    GST_DEBUG_CATEGORY_INIT (lcevcmeta_debug, "lcevcmeta", 0, "LCEVC Metadata");
+
+    const GstMetaInfo *meta = gst_meta_register (GST_LCEVC_META_API_TYPE,
+        "GstLcevcMeta",
+        sizeof (GstLcevcMeta),
+        (GstMetaInitFunction) gst_lcevc_meta_init,
+        (GstMetaFreeFunction) gst_lcevc_meta_free,
+        gst_lcevc_meta_transform);
+    g_once_init_leave ((GstMetaInfo **) & lcevc_meta_info,
+        (GstMetaInfo *) meta);
+  }
+  return lcevc_meta_info;
+}
+
+/**
+ * gst_buffer_get_lcevc_meta:
+ * @buffer: a #GstBuffer
+ *
+ * Find the #GstLcevcMeta on @buffer with the lowest @id.
+ *
+ * Buffers can contain multiple #GstLcevcMeta metadata items when dealing with
+ * multiview buffers.
+ *
+ * Returns: (transfer none) (nullable): the #GstLcevcMeta with lowest id (usually 0) or %NULL when there
+ * is no such metadata on @buffer.
+ *
+ * Since: 1.26
+ */
+GstLcevcMeta *
+gst_buffer_get_lcevc_meta (GstBuffer * buffer)
+{
+  gpointer state = NULL;
+  GstLcevcMeta *out = NULL;
+  GstMeta *meta;
+  const GstMetaInfo *info = GST_LCEVC_META_INFO;
+
+  while ((meta = gst_buffer_iterate_meta (buffer, &state))) {
+    if (meta->info->api == info->api) {
+      GstLcevcMeta *vmeta = (GstLcevcMeta *) meta;
+      if (vmeta->id == 0)
+        return vmeta;           /* Early out for id 0 */
+      if (out == NULL || vmeta->id < out->id)
+        out = vmeta;
+    }
+  }
+  return out;
+}
+
+/**
+ * gst_buffer_get_lcevc_meta_id:
+ * @buffer: a #GstBuffer
+ * @id: a metadata id
+ *
+ * Find the #GstLcevcMeta on @buffer with the given @id.
+ *
+ * Buffers can contain multiple #GstLcevcMeta metadata items when dealing with
+ * multiview buffers.
+ *
+ * Returns: (transfer none) (nullable): the #GstLcevcMeta with @id or %NULL when there is no such metadata
+ * on @buffer.
+ *
+ * Since: 1.26
+ */
+GstLcevcMeta *
+gst_buffer_get_lcevc_meta_id (GstBuffer * buffer, gint id)
+{
+  gpointer state = NULL;
+  GstMeta *meta;
+  const GstMetaInfo *info = GST_LCEVC_META_INFO;
+
+  while ((meta = gst_buffer_iterate_meta (buffer, &state))) {
+    if (meta->info->api == info->api) {
+      GstLcevcMeta *vmeta = (GstLcevcMeta *) meta;
+      if (vmeta->id == id)
+        return vmeta;
+    }
+  }
+  return NULL;
+}
+
+/**
+ * gst_buffer_add_lcevc_meta:
+ * @buffer: a #GstBuffer
+ * @enhancement_data: (transfer none): the parsed LCEVC enhancement data
+ *
+ * Attaches GstLcevcMeta metadata to @buffer.
+ *
+ * Returns: (transfer none): the #GstLcevcMeta on @buffer.
+ *
+ * Since: 1.26
+ */
+GstLcevcMeta *
+gst_buffer_add_lcevc_meta (GstBuffer * buffer, GstBuffer * enhancement_data)
+{
+  GstLcevcMeta *meta;
+
+  meta = (GstLcevcMeta *) gst_buffer_add_meta (buffer, GST_LCEVC_META_INFO,
+      NULL);
+  if (!meta)
+    return NULL;
+
+  meta->id = 0;
+  g_clear_pointer (&meta->enhancement_data, gst_buffer_unref);
+  meta->enhancement_data = gst_buffer_ref (enhancement_data);
+
+  return meta;
+}

subprojects/gst-plugins-bad/gst-libs/gst/codecparsers/gstlcevcmeta.h

@@ -0,0 +1,69 @@
+/* GStreamer LCEVC meta
+ *  Copyright (C) <2024> V-Nova International Limited
+ *
+ * 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_LCEVC_META_H__
+#define __GST_LCEVC_META_H__
+
+#include <gst/gst.h>
+#include <gst/codecparsers/codecparsers-prelude.h>
+
+G_BEGIN_DECLS
+
+#define GST_LCEVC_META_API_TYPE (gst_lcevc_meta_api_get_type())
+#define GST_LCEVC_META_INFO  (gst_lcevc_meta_get_info())
+typedef struct _GstLcevcMeta GstLcevcMeta;
+
+#define GST_CAPS_FEATURE_META_GST_LCEVC_META "meta:GstLcevcMeta"
+
+/**
+ * GstLcevcMeta:
+ * @meta: parent #GstMeta
+ * @id: the id of the LCEVC meta
+ * @enhancement_data: the parsed LCEVC enhancement data
+ *
+ * LCEVC data for LCEVC codecs
+ *
+ * Since: 1.26
+ */
+struct _GstLcevcMeta {
+  GstMeta meta;
+
+  gint id;
+  GstBuffer *enhancement_data;
+};
+
+GST_CODEC_PARSERS_API
+GType gst_lcevc_meta_api_get_type (void);
+
+GST_CODEC_PARSERS_API
+const GstMetaInfo * gst_lcevc_meta_get_info (void);
+
+GST_CODEC_PARSERS_API
+GstLcevcMeta * gst_buffer_get_lcevc_meta (GstBuffer *buffer);
+
+GST_CODEC_PARSERS_API
+GstLcevcMeta * gst_buffer_get_lcevc_meta_id (GstBuffer *buffer, gint id);
+
+GST_CODEC_PARSERS_API
+GstLcevcMeta * gst_buffer_add_lcevc_meta (GstBuffer *buffer,
+    GstBuffer *enhancement_data);
+
+G_END_DECLS
+
+#endif /* __GST_VIDEO_META_H__ */

subprojects/gst-plugins-bad/gst-libs/gst/codecparsers/meson.build

@@ -21,6 +21,7 @@ codecparser_sources = files([
   'gstav1bitwriter.c',
   'gstvp9bitwriter.c',
   'gstjpegbitwriter.c',
+  'gstlcevcmeta.c',
 ])
 codecparser_headers = [
   'codecparsers-prelude.h',
@@ -36,6 +37,7 @@ codecparser_headers = [
   'gstmpegvideometa.h',
   'gstvp9parser.h',
   'gstav1parser.h',
+  'gstlcevcmeta.h',
 ]
 install_headers(codecparser_headers, subdir : 'gstreamer-1.0/gst/codecparsers')