lcevcdecoder: Add new lcevch264decodebin element

This new element wraps both the base H264 decoder and lcevcdec elements into a
bin so that LCEVC decoding works with auto-plugging elements such as decodebin.
By default, the H264 decoder element with higher rank is used as base decoder,
but any particular H264 decoder can be used by manually setting the base-decoder
property.

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

subprojects/gst-plugins-bad/ext/lcevcdecoder/gstlcevcdecodebin.c

@@ -0,0 +1,332 @@
+/* GStreamer
+ *  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 <gst/pbutils/pbutils.h>
+
+#include "gstlcevcdecutils.h"
+#include "gstlcevcdecodebin.h"
+
+enum
+{
+  PROP_0,
+  PROP_BASE_DECODER,
+};
+
+GST_DEBUG_CATEGORY_STATIC (lcevcdecodebin_debug);
+#define GST_CAT_DEFAULT (lcevcdecodebin_debug)
+
+typedef struct
+{
+  /* Props */
+  gchar *base_decoder;
+
+  gboolean constructed;
+  const gchar *missing_element;
+} GstLcevcDecodeBinPrivate;
+
+#define gst_lcevc_decode_bin_parent_class parent_class
+G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GstLcevcDecodeBin, gst_lcevc_decode_bin,
+    GST_TYPE_BIN,
+    G_ADD_PRIVATE (GstLcevcDecodeBin);
+    GST_DEBUG_CATEGORY_INIT (lcevcdecodebin_debug, "lcevcdecodebin", 0,
+        "lcevcdecodebin"));
+
+static GstStaticPadTemplate gst_lcevc_decode_bin_src_template =
+GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE
+        (GST_LCEVC_DEC_UTILS_SUPPORTED_FORMATS))
+    );
+
+static gboolean
+gst_lcevc_decode_bin_open (GstLcevcDecodeBin * self)
+{
+  GstLcevcDecodeBinPrivate *priv =
+      gst_lcevc_decode_bin_get_instance_private (self);
+
+  if (priv->missing_element) {
+    gst_element_post_message (GST_ELEMENT (self),
+        gst_missing_element_message_new (GST_ELEMENT (self),
+            priv->missing_element));
+  } else if (!priv->constructed) {
+    GST_ELEMENT_ERROR (self, CORE, FAILED, (NULL),
+        ("Failed to construct or link LCEVC decoder elements."));
+  }
+
+  return priv->constructed;
+}
+
+static GstStateChangeReturn
+gst_lcevc_decode_bin_change_state (GstElement * element,
+    GstStateChange transition)
+{
+  GstLcevcDecodeBin *self = GST_LCEVC_DECODE_BIN (element);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_NULL_TO_READY:
+      if (!gst_lcevc_decode_bin_open (self))
+        return GST_STATE_CHANGE_FAILURE;
+      break;
+    default:
+      break;
+  }
+
+  return GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+}
+
+static char *
+gst_lcevc_decode_bin_find_base_decoder (GstLcevcDecodeBin * self)
+{
+  GstLcevcDecodeBinClass *klass = GST_LCEVC_DECODE_BIN_GET_CLASS (self);
+  GList *factories;
+  gchar *res = NULL;
+  GstCaps *accepted_caps;
+
+  /* Get the accepted sink caps for the base decoder */
+  if (!klass->get_base_decoder_sink_caps)
+    return NULL;
+  accepted_caps = klass->get_base_decoder_sink_caps (self);
+  if (!accepted_caps)
+    return NULL;
+
+  /* Get all decoders and sort them by rank */
+  factories =
+      gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_DECODER,
+      GST_RANK_MARGINAL);
+  factories = g_list_sort (factories, gst_plugin_feature_rank_compare_func);
+
+  /* Select the first compatible factory (list is sorted by rank) */
+  while (factories) {
+    GstElementFactory *f = factories->data;
+    const GList *pad_templates;
+    gboolean is_compatible = FALSE;
+
+    factories = g_list_next (factories);
+
+    pad_templates = gst_element_factory_get_static_pad_templates (f);
+    while (pad_templates) {
+      GstStaticPadTemplate *st = (GstStaticPadTemplate *) pad_templates->data;
+      GstCaps *template_caps;
+
+      pad_templates = g_list_next (pad_templates);
+
+      /* Get the sink pad template */
+      if (st->direction != GST_PAD_SINK)
+        continue;
+
+      /* Skip any pad that is not h264 with lcevc=false */
+      template_caps = gst_static_pad_template_get_caps (st);
+      if (!gst_caps_can_intersect (template_caps, accepted_caps)) {
+        gst_caps_unref (template_caps);
+        continue;
+      }
+
+      gst_caps_unref (template_caps);
+      is_compatible = TRUE;
+      break;
+    }
+
+    if (is_compatible) {
+      res = gst_object_get_name (GST_OBJECT (f));
+      break;
+    }
+  }
+
+  g_list_free (factories);
+  gst_caps_unref (accepted_caps);
+  return res;
+}
+
+static void
+gst_lcevc_decode_bin_constructed (GObject * obj)
+{
+  GstLcevcDecodeBin *self = GST_LCEVC_DECODE_BIN (obj);
+  GstLcevcDecodeBinClass *klass = GST_LCEVC_DECODE_BIN_GET_CLASS (self);
+  GstLcevcDecodeBinPrivate *priv =
+      gst_lcevc_decode_bin_get_instance_private (self);
+  GstPad *src_gpad, *sink_gpad;
+  GstPad *src_pad = NULL, *sink_pad = NULL;
+  GstElement *base_decoder = NULL;
+  GstElement *lcevcdec = NULL;
+
+  /* setup ghost pads */
+  sink_gpad = gst_ghost_pad_new_no_target_from_template ("sink",
+      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (klass), "sink"));
+  gst_element_add_pad (GST_ELEMENT (self), sink_gpad);
+
+  src_gpad = gst_ghost_pad_new_no_target_from_template ("src",
+      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (klass), "src"));
+  gst_element_add_pad (GST_ELEMENT (self), src_gpad);
+
+  /* Create base decoder if name is given, otherwise fine one */
+  if (priv->base_decoder) {
+    base_decoder = gst_element_factory_make (priv->base_decoder, NULL);
+    if (!base_decoder) {
+      priv->missing_element = priv->base_decoder;
+      goto error;
+    }
+  } else {
+    gchar *name = gst_lcevc_decode_bin_find_base_decoder (self);
+    if (!name)
+      goto error;
+    base_decoder = gst_element_factory_make (name, NULL);
+    g_free (name);
+    if (!base_decoder)
+      goto error;
+  }
+
+  /* Create LCEVC decoder */
+  lcevcdec = gst_element_factory_make ("lcevcdec", NULL);
+  if (!lcevcdec) {
+    priv->missing_element = "lcevcdec";
+    goto error;
+  }
+
+  if (!gst_bin_add (GST_BIN (self), base_decoder))
+    goto error;
+  if (!gst_bin_add (GST_BIN (self), lcevcdec))
+    goto error;
+
+  if (!gst_element_link (base_decoder, lcevcdec))
+    goto error;
+
+  /* link elements */
+  sink_pad = gst_element_get_static_pad (base_decoder, "sink");
+  gst_ghost_pad_set_target (GST_GHOST_PAD (sink_gpad), sink_pad);
+  gst_clear_object (&sink_pad);
+
+  src_pad = gst_element_get_static_pad (lcevcdec, "src");
+  gst_ghost_pad_set_target (GST_GHOST_PAD (src_gpad), src_pad);
+  gst_object_unref (src_pad);
+
+  /* signal success, we will handle this in NULL->READY transition */
+  priv->constructed = TRUE;
+  G_OBJECT_CLASS (parent_class)->constructed (obj);
+  return;
+
+error:
+  gst_clear_object (&base_decoder);
+  gst_clear_object (&lcevcdec);
+
+  priv->constructed = FALSE;
+  G_OBJECT_CLASS (parent_class)->constructed (obj);
+}
+
+static void
+gst_lcevc_decode_bin_finalize (GObject * obj)
+{
+  GstLcevcDecodeBin *self = GST_LCEVC_DECODE_BIN (obj);
+  GstLcevcDecodeBinPrivate *priv =
+      gst_lcevc_decode_bin_get_instance_private (self);
+
+  g_free (priv->base_decoder);
+
+  G_OBJECT_CLASS (parent_class)->finalize (obj);
+}
+
+
+static void
+gst_lcevc_decode_bin_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  GstLcevcDecodeBin *self = GST_LCEVC_DECODE_BIN (object);
+  GstLcevcDecodeBinPrivate *priv =
+      gst_lcevc_decode_bin_get_instance_private (self);
+
+  switch (prop_id) {
+    case PROP_BASE_DECODER:
+      g_clear_pointer (&priv->base_decoder, g_free);
+      priv->base_decoder = g_value_dup_string (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+gst_lcevc_decode_bin_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec)
+{
+  GstLcevcDecodeBin *self = GST_LCEVC_DECODE_BIN (object);
+  GstLcevcDecodeBinPrivate *priv =
+      gst_lcevc_decode_bin_get_instance_private (self);
+
+  switch (prop_id) {
+    case PROP_BASE_DECODER:
+      g_value_set_string (value, priv->base_decoder);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+gst_lcevc_decode_bin_handle_message (GstBin * bin, GstMessage * message)
+{
+  /* We use bin as source for latency messages (fixes decodebin3 autopluggin) */
+  switch (message->type) {
+    case GST_MESSAGE_LATENCY:
+      gst_message_unref (message);
+      message = gst_message_new_latency (GST_OBJECT (bin));
+      return;
+    default:
+      break;
+  }
+
+  GST_BIN_CLASS (parent_class)->handle_message (bin, message);
+}
+
+static void
+gst_lcevc_decode_bin_class_init (GstLcevcDecodeBinClass * klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
+  GstBinClass *bin_class = GST_BIN_CLASS (klass);
+
+  gst_element_class_add_static_pad_template (element_class,
+      &gst_lcevc_decode_bin_src_template);
+  element_class->change_state =
+      GST_DEBUG_FUNCPTR (gst_lcevc_decode_bin_change_state);
+
+  gst_type_mark_as_plugin_api (GST_TYPE_LCEVC_DECODE_BIN, 0);
+
+  gobject_class->constructed = gst_lcevc_decode_bin_constructed;
+  gobject_class->finalize = gst_lcevc_decode_bin_finalize;
+  gobject_class->set_property = gst_lcevc_decode_bin_set_property;
+  gobject_class->get_property = gst_lcevc_decode_bin_get_property;
+
+  bin_class->handle_message = gst_lcevc_decode_bin_handle_message;
+
+  g_object_class_install_property (gobject_class, PROP_BASE_DECODER,
+      g_param_spec_string ("base-decoder", "Base Decoder",
+          "The base decoder element name (NULL for automatic)",
+          NULL, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+}
+
+static void
+gst_lcevc_decode_bin_init (GstLcevcDecodeBin * self)
+{
+}

subprojects/gst-plugins-bad/ext/lcevcdecoder/gstlcevcdecodebin.h

@@ -0,0 +1,48 @@
+/* GStreamer
+ *  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_DECODE_BIN_H__
+#define __GST_LCEVC_DECODE_BIN_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+
+/* When wrapping, use the original rank plus this offset. The ad-hoc rules is
+ * that hardware implementation will use PRIMARY+1 or +2 to override the
+ * software decoder, so the offset must be large enough to jump over those.
+ * This should also be small enough so that a marginal (64) or secondary
+ * wrapper does not cross the PRIMARY line.
+ */
+#define GST_LCEVC_DECODE_BIN_RANK_OFFSET 10
+
+#define GST_TYPE_LCEVC_DECODE_BIN (gst_lcevc_decode_bin_get_type())
+G_DECLARE_DERIVABLE_TYPE (GstLcevcDecodeBin,
+    gst_lcevc_decode_bin, GST, LCEVC_DECODE_BIN, GstBin);
+
+struct _GstLcevcDecodeBinClass
+{
+  GstBinClass parent_class;
+
+  GstCaps * (*get_base_decoder_sink_caps) (GstLcevcDecodeBin * base);
+};
+
+G_END_DECLS
+
+#endif /* __GST_LCEVC_DECODE_BIN_H__ */

subprojects/gst-plugins-bad/ext/lcevcdecoder/gstlcevch264decodebin.c

@@ -0,0 +1,72 @@
+/* GStreamer
+ *  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 "gstlcevch264decodebin.h"
+
+static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS ("video/x-h264, lcevc = (boolean) true")
+    );
+
+struct _GstLcevcH264DecodeBin
+{
+  GstLcevcDecodeBin parent;
+};
+
+#define gst_lcevc_h264_decode_bin_parent_class parent_class
+G_DEFINE_TYPE (GstLcevcH264DecodeBin, gst_lcevc_h264_decode_bin,
+    GST_TYPE_LCEVC_DECODE_BIN);
+
+GST_ELEMENT_REGISTER_DEFINE (lcevch264decodebin, "lcevch264decodebin",
+    GST_RANK_PRIMARY + GST_LCEVC_DECODE_BIN_RANK_OFFSET,
+    GST_TYPE_LCEVC_H264_DECODE_BIN);
+
+static GstCaps *
+gst_lcevc_h264_decode_bin_get_base_decoder_sink_caps (GstLcevcDecodeBin * base)
+{
+  return gst_caps_new_simple ("video/x-h264",
+      "lcevc", G_TYPE_BOOLEAN, FALSE, NULL);
+}
+
+static void
+gst_lcevc_h264_decode_bin_class_init (GstLcevcH264DecodeBinClass * klass)
+{
+  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
+  GstLcevcDecodeBinClass *ldb_class = GST_LCEVC_DECODE_BIN_CLASS (klass);
+
+  gst_element_class_add_static_pad_template (element_class, &sink_template);
+
+  gst_element_class_set_static_metadata (element_class,
+      "H264 Lcevc Decode Bin", "Codec/Decoder/Video",
+      "Wrapper bin to decode H264 with LCEVC data.",
+      "Julian Bouzas <julian.bouzas@collabora.com>");
+
+  ldb_class->get_base_decoder_sink_caps =
+      gst_lcevc_h264_decode_bin_get_base_decoder_sink_caps;
+}
+
+static void
+gst_lcevc_h264_decode_bin_init (GstLcevcH264DecodeBin * self)
+{
+}

subprojects/gst-plugins-bad/ext/lcevcdecoder/gstlcevch264decodebin.h

@@ -0,0 +1,34 @@
+/* GStreamer
+ *  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_H264_DECODE_BIN_H__
+#define __GST_LCEVC_H264_DECODE_BIN_H__
+
+#include "gstlcevcdecodebin.h"
+
+G_BEGIN_DECLS
+
+#define GST_TYPE_LCEVC_H264_DECODE_BIN (gst_lcevc_h264_decode_bin_get_type())
+G_DECLARE_FINAL_TYPE (GstLcevcH264DecodeBin, gst_lcevc_h264_decode_bin,
+    GST, LCEVC_H264_DECODE_BIN, GstLcevcDecodeBin);
+
+GST_ELEMENT_REGISTER_DECLARE (lcevch264decodebin);
+
+G_END_DECLS
+#endif

subprojects/gst-plugins-bad/ext/lcevcdecoder/plugin.c

@@ -24,6 +24,7 @@
 #include <gst/gst.h>
 
 #include "gstlcevcdec.h"
+#include "gstlcevch264decodebin.h"
 
 static gboolean
 plugin_init (GstPlugin * plugin)
@@ -31,6 +32,7 @@ plugin_init (GstPlugin * plugin)
   gboolean ret = FALSE;
 
   ret |= GST_ELEMENT_REGISTER (lcevcdec, plugin);
+  ret |= GST_ELEMENT_REGISTER (lcevch264decodebin, plugin);
 
   return ret;
 }