x264enc: expose nal-hrd property

It can be used to force true CBR, and will cause the encoder
to output null padding packets.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/908>

subprojects/gst-plugins-ugly/docs/gst_plugins_cache.json

@@ -1014,6 +1014,18 @@
                         "type": "gchararray",
                         "writable": true
                     },
+                    "nal-hrd": {
+                        "blurb": "Signal Hypothetical Reference Decoder information",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "none (0)",
+                        "mutable": "null",
+                        "readable": true,
+                        "type": "GstX264EncNalHrd",
+                        "writable": true
+                    },
                     "noise-reduction": {
                         "blurb": "Noise reduction strength",
                         "conditionally-available": false,
@@ -1399,6 +1411,26 @@
                     }
                 ]
             },
+            "GstX264EncNalHrd": {
+                "kind": "enum",
+                "values": [
+                    {
+                        "desc": "None",
+                        "name": "none",
+                        "value": "0"
+                    },
+                    {
+                        "desc": "Variable bitrate",
+                        "name": "vbr",
+                        "value": "1"
+                    },
+                    {
+                        "desc": "Constant bitrate",
+                        "name": "cbr",
+                        "value": "2"
+                    }
+                ]
+            },
             "GstX264EncPass": {
                 "kind": "enum",
                 "values": [

subprojects/gst-plugins-ugly/docs/meson.build

@@ -114,9 +114,9 @@ gst_plugins_doc = run_command(
     '--index', cdir / 'index.md',
     '--gst_index', cdir / 'index.md',
     '--gst_c_sources',
-        root_rel / 'sys/*/*.[ch]',
+        cdir / root_rel / 'sys/*/*.[ch]',
-        root_rel / 'ext/*/*.[ch]',
+        cdir / root_rel / 'ext/*/*.[ch]',
-        root_rel / 'gst/*/*.[ch]',
+        cdir / root_rel / 'gst/*/*.[ch]',
     '--gst_c_source_filters', excludes,
     '--gst_cache_file', plugins_cache,
     check: true,

subprojects/gst-plugins-ugly/ext/x264/gstx264enc.c

@@ -422,6 +422,7 @@ enum
   ARG_TUNE,
   ARG_FRAME_PACKING,
   ARG_INSERT_VUI,
+  ARG_NAL_HRD,
 };
 
 #define ARG_THREADS_DEFAULT            0        /* 0 means 'auto' which is 1.5x number of CPU cores */
@@ -464,6 +465,7 @@ static GString *x264enc_defaults;
 #define ARG_TUNE_DEFAULT               0        /* no tuning */
 #define ARG_FRAME_PACKING_DEFAULT      -1       /* automatic (none, or from input caps) */
 #define ARG_INSERT_VUI_DEFAULT         TRUE
+#define ARG_NAL_HRD_DEFAULT            0
 
 enum
 {
@@ -504,6 +506,25 @@ gst_x264_enc_pass_get_type (void)
   return pass_type;
 }
 
+#define GST_X264_ENC_NAL_HRD_TYPE (gst_x264_enc_nal_hrd_get_type())
+static GType
+gst_x264_enc_nal_hrd_get_type (void)
+{
+  static GType nal_hrd_type = 0;
+
+  static const GEnumValue nal_hrd_types[] = {
+    {GST_X264_ENC_NAL_HRD_NONE, "None", "none"},
+    {GST_X264_ENC_NAL_HRD_VBR, "Variable bitrate", "vbr"},
+    {GST_X264_ENC_NAL_HRD_CBR, "Constant bitrate", "cbr"},
+    {0, NULL, NULL}
+  };
+
+  if (!nal_hrd_type) {
+    nal_hrd_type = g_enum_register_static ("GstX264EncNalHrd", nal_hrd_types);
+  }
+  return nal_hrd_type;
+}
+
 #define GST_X264_ENC_ME_TYPE (gst_x264_enc_me_get_type())
 static GType
 gst_x264_enc_me_get_type (void)
@@ -1209,6 +1230,25 @@ gst_x264_enc_class_init (GstX264EncClass * klass)
   g_string_append_printf (x264enc_defaults, ":interlaced=%d",
       ARG_INTERLACED_DEFAULT);
 
+  /**
+   * x264enc:nal-hrd:
+   *
+   * Signal Hypothetical Reference Decoder information.
+   *
+   * Required for Blu-ray streams, television broadcast and a
+   * few other specialist areas.
+   *
+   * It can be used for instance to force true CBR, and will cause
+   * the encoder to output NULL padding packets.
+   *
+   * Since: 1.26
+   */
+  g_object_class_install_property (gobject_class, ARG_NAL_HRD,
+      g_param_spec_enum ("nal-hrd", "NAL HRD",
+          "Signal Hypothetical Reference Decoder information",
+          GST_X264_ENC_NAL_HRD_TYPE, ARG_NAL_HRD_DEFAULT,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
   /* append deblock parameters */
   g_string_append_printf (x264enc_defaults, ":deblock=0,0");
   /* append weighted prediction parameter */
@@ -1243,6 +1283,7 @@ gst_x264_enc_class_init (GstX264EncClass * klass)
   gst_type_mark_as_plugin_api (GST_X264_ENC_PSY_TUNE_TYPE, 0);
   gst_type_mark_as_plugin_api (GST_X264_ENC_SPEED_PRESET_TYPE, 0);
   gst_type_mark_as_plugin_api (GST_X264_ENC_TUNE_TYPE, 0);
+  gst_type_mark_as_plugin_api (GST_X264_ENC_NAL_HRD_TYPE, 0);
 }
 
 /* *INDENT-OFF* */
@@ -1340,6 +1381,7 @@ gst_x264_enc_init (GstX264Enc * encoder)
   encoder->tune = ARG_TUNE_DEFAULT;
   encoder->frame_packing = ARG_FRAME_PACKING_DEFAULT;
   encoder->insert_vui = ARG_INSERT_VUI_DEFAULT;
+  encoder->nal_hrd = ARG_NAL_HRD_DEFAULT;
 
   encoder->bitrate_manager =
       gst_encoder_bitrate_profile_manager_new (ARG_BITRATE_DEFAULT);
@@ -1915,6 +1957,8 @@ skip_vui_parameters:
 
   GST_OBJECT_UNLOCK (encoder);
 
+  encoder->x264param.i_nal_hrd = encoder->nal_hrd;
+
   encoder->x264enc = encoder->vtable->x264_encoder_open (&encoder->x264param);
   if (!encoder->x264enc) {
     GST_ELEMENT_ERROR (encoder, STREAM, ENCODE,
@@ -2988,6 +3032,9 @@ gst_x264_enc_set_property (GObject * object, guint prop_id,
     case ARG_INSERT_VUI:
       encoder->insert_vui = g_value_get_boolean (value);
       break;
+    case ARG_NAL_HRD:
+      encoder->nal_hrd = g_value_get_enum (value);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -3132,6 +3179,9 @@ gst_x264_enc_get_property (GObject * object, guint prop_id,
     case ARG_INSERT_VUI:
       g_value_set_boolean (value, encoder->insert_vui);
       break;
+    case ARG_NAL_HRD:
+      g_value_set_enum (value, encoder->nal_hrd);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;

subprojects/gst-plugins-ugly/ext/x264/gstx264enc.h

@@ -113,6 +113,7 @@ struct _GstX264Enc
   GString *option_string; /* used by set prop */
   gint frame_packing;
   gboolean insert_vui;
+  gint nal_hrd;
 
   /* input description */
   GstVideoCodecState *input_state;
@@ -136,6 +137,24 @@ struct _GstX264EncClass
   GstVideoEncoderClass parent_class;
 };
 
+/**
+ * GstX264EncNalHrd:
+ * @GST_X264_ENC_NAL_HRD_NONE: Specify no HRD information
+ * @GST_X264_ENC_NAL_HRD_VBR: Specify HRD information
+ * @GST_X264_ENC_NAL_HRD_CBR: Specify HRD information and pack the bitstream
+ *
+ * Signal HRD information. Required for Blu-ray streams,
+ * television broadcast and a few other specialist areas.
+ *
+ * Since: 1.26
+ */
+typedef enum
+{
+  GST_X264_ENC_NAL_HRD_NONE = 0,
+  GST_X264_ENC_NAL_HRD_VBR = 1,
+  GST_X264_ENC_NAL_HRD_CBR = 2,
+} GstX264EncNalHrd;
+
 GType gst_x264_enc_get_type (void);
 GST_ELEMENT_REGISTER_DECLARE (x264enc);