v4l2codecs: Add skeleton of H264 decoder

This introduces the skeleton of the H264 decoder. The plugin will list the
devices and register a subclass of the GstV4L2CodecH264Dec base class. The
subclass will pick the required specific information from the GstV4L2Device
stored in the subclass structure.

sys/v4l2codecs/gstv4l2codech264dec.c

@@ -0,0 +1,290 @@
+/* GStreamer
+ * Copyright (C) 2020 Nicolas Dufresne <nicolas.dufresne@collabora.com>
+ *
+ * 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 "gstv4l2codech264dec.h"
+
+GST_DEBUG_CATEGORY_STATIC (v4l2_h264dec_debug);
+#define GST_CAT_DEFAULT v4l2_h264dec_debug
+
+enum
+{
+  PROP_0,
+  PROP_LAST = PROP_0
+};
+
+static GstStaticPadTemplate sink_template =
+GST_STATIC_PAD_TEMPLATE (GST_VIDEO_DECODER_SINK_NAME,
+    GST_PAD_SINK, GST_PAD_ALWAYS,
+    GST_STATIC_CAPS ("video/x-h264, "
+        "stream-format=(string) byte-stream, alignment=(string) au")
+    );
+
+static GstStaticPadTemplate src_template =
+GST_STATIC_PAD_TEMPLATE (GST_VIDEO_DECODER_SRC_NAME,
+    GST_PAD_SRC, GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("{ NV12, YUY2 }")));
+
+struct _GstV4l2CodecH264Dec
+{
+  GstH264Decoder parent;
+  GstV4l2Decoder *decoder;
+  GstVideoCodecState *output_state;
+  GstVideoFormat out_format;
+  gint width;
+  gint height;
+};
+
+G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GstV4l2CodecH264Dec,
+    gst_v4l2_codec_h264_dec, GST_TYPE_H264_DECODER,
+    GST_DEBUG_CATEGORY_INIT (v4l2_h264dec_debug, "v4l2codecs-h264dec", 0,
+        "V4L2 stateless h264 decoder"));
+#define parent_class gst_v4l2_codec_h264_dec_parent_class
+
+static gboolean
+gst_v4l2_codec_h264_dec_open (GstVideoDecoder * decoder)
+{
+  return TRUE;
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_close (GstVideoDecoder * decoder)
+{
+  return TRUE;
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_stop (GstVideoDecoder * decoder)
+{
+  GstV4l2CodecH264Dec *self = GST_V4L2_CODEC_H264_DEC (decoder);
+
+  if (self->output_state)
+    gst_video_codec_state_unref (self->output_state);
+  self->output_state = NULL;
+
+  return GST_VIDEO_DECODER_CLASS (parent_class)->stop (decoder);
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_negotiate (GstVideoDecoder * decoder)
+{
+  GstV4l2CodecH264Dec *self = GST_V4L2_CODEC_H264_DEC (decoder);
+  GstH264Decoder *h264dec = GST_H264_DECODER (decoder);
+
+  GST_DEBUG_OBJECT (self, "negotiate");
+
+  if (self->output_state)
+    gst_video_codec_state_unref (self->output_state);
+
+  self->output_state =
+      gst_video_decoder_set_output_state (GST_VIDEO_DECODER (self),
+      self->out_format, self->width, self->height, h264dec->input_state);
+
+  self->output_state->caps = gst_video_info_to_caps (&self->output_state->info);
+
+  return GST_VIDEO_DECODER_CLASS (parent_class)->negotiate (decoder);
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_decide_allocation (GstVideoDecoder * decoder,
+    GstQuery * query)
+{
+  return GST_VIDEO_DECODER_CLASS (parent_class)->decide_allocation
+      (decoder, query);
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_new_sequence (GstH264Decoder * decoder,
+    const GstH264SPS * sps, gint max_dpb_size)
+{
+  /* TODO check if we need to setup a new format */
+  return TRUE;
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_start_picture (GstH264Decoder * decoder,
+    GstH264Picture * picture, GstH264Slice * slice, GstH264Dpb * dpb)
+{
+  return FALSE;
+}
+
+static GstFlowReturn
+gst_v4l2_codec_h264_dec_output_picture (GstH264Decoder * decoder,
+    GstH264Picture * picture)
+{
+  return GST_FLOW_ERROR;
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_end_picture (GstH264Decoder * decoder,
+    GstH264Picture * picture)
+{
+  return TRUE;
+}
+
+static gboolean
+gst_v4l2_codec_h264_dec_decode_slice (GstH264Decoder * decoder,
+    GstH264Picture * picture, GstH264Slice * slice)
+{
+  return TRUE;
+}
+
+static void
+gst_v4l2_codec_h264_dec_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  GstV4l2CodecH264Dec *self = GST_V4L2_CODEC_H264_DEC (object);
+  GObject *dec = G_OBJECT (self->decoder);
+
+  switch (prop_id) {
+    default:
+      gst_v4l2_decoder_set_property (dec, prop_id - PROP_LAST, value, pspec);
+      break;
+  }
+}
+
+static void
+gst_v4l2_codec_h264_dec_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec)
+{
+  GstV4l2CodecH264Dec *self = GST_V4L2_CODEC_H264_DEC (object);
+  GObject *dec = G_OBJECT (self->decoder);
+
+  switch (prop_id) {
+    default:
+      gst_v4l2_decoder_get_property (dec, prop_id - PROP_LAST, value, pspec);
+      break;
+  }
+}
+
+static void
+gst_v4l2_codec_h264_dec_init (GstV4l2CodecH264Dec * self)
+{
+}
+
+static void
+gst_v4l2_codec_h264_dec_subinit (GstV4l2CodecH264Dec * self,
+    GstV4l2CodecH264DecClass * klass)
+{
+  self->decoder = gst_v4l2_decoder_new (klass->device);
+}
+
+static void
+gst_v4l2_codec_h264_dec_dispose (GObject * object)
+{
+  GstV4l2CodecH264Dec *self = GST_V4L2_CODEC_H264_DEC (object);
+
+  g_clear_object (&self->decoder);
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gst_v4l2_codec_h264_dec_class_init (GstV4l2CodecH264DecClass * klass)
+{
+}
+
+static void
+gst_v4l2_codec_h264_dec_subclass_init (GstV4l2CodecH264DecClass * klass,
+    GstV4l2CodecDevice * device)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
+  GstVideoDecoderClass *decoder_class = GST_VIDEO_DECODER_CLASS (klass);
+  GstH264DecoderClass *h264decoder_class = GST_H264_DECODER_CLASS (klass);
+
+  gobject_class->set_property = gst_v4l2_codec_h264_dec_set_property;
+  gobject_class->get_property = gst_v4l2_codec_h264_dec_get_property;
+  gobject_class->dispose = gst_v4l2_codec_h264_dec_dispose;
+
+  gst_element_class_set_static_metadata (element_class,
+      "V4L2 Stateless H.264 Video Decoder",
+      "Codec/Decoder/Video/Hardware",
+      "A V4L2 based H.264 video decoder",
+      "Nicolas Dufresne <nicolas.dufresne@collabora.com>");
+
+  gst_element_class_add_static_pad_template (element_class, &sink_template);
+  gst_element_class_add_static_pad_template (element_class, &src_template);
+
+  decoder_class->open = GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_open);
+  decoder_class->close = GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_close);
+  decoder_class->stop = GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_stop);
+  decoder_class->negotiate =
+      GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_negotiate);
+  decoder_class->decide_allocation =
+      GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_decide_allocation);
+
+  h264decoder_class->new_sequence =
+      GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_new_sequence);
+  h264decoder_class->output_picture =
+      GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_output_picture);
+  h264decoder_class->start_picture =
+      GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_start_picture);
+  h264decoder_class->decode_slice =
+      GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_decode_slice);
+  h264decoder_class->end_picture =
+      GST_DEBUG_FUNCPTR (gst_v4l2_codec_h264_dec_end_picture);
+
+  klass->device = device;
+  gst_v4l2_decoder_install_properties (gobject_class, PROP_LAST, device);
+}
+
+void
+gst_v4l2_codec_h264_dec_register (GstPlugin * plugin,
+    GstV4l2CodecDevice * device, guint rank)
+{
+  GTypeQuery type_query;
+  GTypeInfo type_info = { 0, };
+  GType subtype;
+  gchar *type_name;
+
+  g_type_query (GST_TYPE_V4L2_CODEC_H264_DEC, &type_query);
+  memset (&type_info, 0, sizeof (type_info));
+  type_info.class_size = type_query.class_size;
+  type_info.instance_size = type_query.instance_size;
+  type_info.class_init = (GClassInitFunc) gst_v4l2_codec_h264_dec_subclass_init;
+  type_info.class_data = gst_mini_object_ref (GST_MINI_OBJECT (device));
+  type_info.instance_init = (GInstanceInitFunc) gst_v4l2_codec_h264_dec_subinit;
+  GST_MINI_OBJECT_FLAG_SET (device, GST_MINI_OBJECT_FLAG_MAY_BE_LEAKED);
+
+  /* The first decoder to be registered should use a constant name, like
+   * v4l2slh264dec, for any additional decoders, we create unique names. Decoder
+   * names may change between boots, so this should help gain stable names for
+   * the most common use cases. SL stands for state-less, we differentiate
+   * with v4l2h264dec as this element may not have the same properties */
+  type_name = g_strdup ("v4l2slh264dec");
+
+  if (g_type_from_name (type_name) != 0) {
+    gchar *basename = g_path_get_basename (device->video_device_path);
+    g_free (type_name);
+    type_name = g_strdup_printf ("v4l2sl%sh264dec", basename);
+    g_free (basename);
+  }
+
+  subtype = g_type_register_static (GST_TYPE_V4L2_CODEC_H264_DEC, type_name,
+      &type_info, 0);
+
+  if (!gst_element_register (plugin, type_name, rank, subtype))
+    GST_WARNING ("Failed to register plugin '%s'", type_name);
+
+  g_free (type_name);
+}

sys/v4l2codecs/gstv4l2codech264dec.h

@@ -0,0 +1,53 @@
+/* GStreamer
+ * Copyright (C) 2020 Nicolas Dufresne <nicolas.dufresne@collabora.com>
+ *
+ * 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_V4L2_CODEC_H264_DEC_H__
+#define __GST_V4L2_CODEC_H264_DEC_H__
+
+#define GST_USE_UNSTABLE_API
+#include <gst/codecs/gsth264decoder.h>
+
+#include "gstv4l2decoder.h"
+
+G_BEGIN_DECLS
+
+#define GST_TYPE_V4L2_CODEC_H264_DEC           (gst_v4l2_codec_h264_dec_get_type())
+#define GST_V4L2_CODEC_H264_DEC(obj)           (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_V4L2_CODEC_H264_DEC,GstV4l2CodecH264Dec))
+#define GST_V4L2_CODEC_H264_DEC_CLASS(klass)   (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_V4L2_CODEC_H264_DEC,GstV4l2CodecH264DecClass))
+#define GST_V4L2_CODEC_H264_DEC_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TYPE_V4L2_CODEC_H264_DEC, GstV4l2CodecH264DecClass))
+#define GST_IS_V4L2_CODEC_H264_DEC(obj)        (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_V4L2_CODEC_H264_DEC))
+#define GST_IS_V4L2_CODEC_H264_DEC_CLASS(obj)  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_V4L2_CODEC_H264_DEC))
+
+typedef struct _GstV4l2CodecH264Dec GstV4l2CodecH264Dec;
+typedef struct _GstV4l2CodecH264DecClass GstV4l2CodecH264DecClass;
+
+struct _GstV4l2CodecH264DecClass
+{
+  GstH264DecoderClass parent_class;
+  GstV4l2CodecDevice *device;
+};
+
+GType gst_v4l2_codec_h264_dec_get_type (void);
+void  gst_v4l2_codec_h264_dec_register (GstPlugin * plugin,
+                                        GstV4l2CodecDevice * device,
+                                        guint rank);
+
+G_END_DECLS
+
+#endif /* __GST_D3D11_H264_DEC_H__ */

sys/v4l2codecs/gstv4l2decoder.c

@@ -128,7 +128,7 @@ gst_v4l2_decoder_open (GstV4l2Decoder * self)
 }
 
 gboolean
-gst_v4l2_decoder_enum_input_fmt (GstV4l2Decoder * self, gint i,
+gst_v4l2_decoder_enum_sink_fmt (GstV4l2Decoder * self, gint i,
     guint32 * out_fmt)
 {
   struct v4l2_fmtdesc fmtdesc = { i, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE, };

sys/v4l2codecs/gstv4l2decoder.h

@@ -34,7 +34,7 @@ GstV4l2Decoder *  gst_v4l2_decoder_new (GstV4l2CodecDevice * device);
 
 gboolean          gst_v4l2_decoder_open (GstV4l2Decoder * decoder);
 
-gboolean          gst_v4l2_decoder_enum_input_fmt (GstV4l2Decoder * self,
+gboolean          gst_v4l2_decoder_enum_sink_fmt (GstV4l2Decoder * self,
                                                   gint i, guint32 * out_fmt);
 
 void              gst_v4l2_decoder_install_properties (GObjectClass * gobject_class,

sys/v4l2codecs/meson.build

@@ -1,6 +1,7 @@
 v4l2codecs_sources = [
   'plugin.c',
   'gstv4l2codecdevice.c',
+  'gstv4l2codech264dec.c',
   'gstv4l2decoder.c',
 ]
 

sys/v4l2codecs/plugin.c

@@ -22,16 +22,61 @@
 #include "config.h"
 #endif
 
-#include <gst/gst.h>
+#include "gstv4l2codecdevice.h"
+#include "gstv4l2codech264dec.h"
+#include "gstv4l2decoder.h"
+#include "linux/h264-ctrls.h"
+#include "linux/media.h"
 
 #define GST_CAT_DEFAULT gstv4l2codecs_debug
 GST_DEBUG_CATEGORY (gstv4l2codecs_debug);
 
+static void
+register_video_decoder (GstPlugin * plugin, GstV4l2CodecDevice * device)
+{
+  GstV4l2Decoder *decoder = gst_v4l2_decoder_new (device);
+  gint i;
+  guint32 fmt;
+
+  if (!gst_v4l2_decoder_open (decoder)) {
+    g_object_unref (decoder);
+    return;
+  }
+
+  for (i = 0; gst_v4l2_decoder_enum_sink_fmt (decoder, i, &fmt); i++) {
+    switch (fmt) {
+      case V4L2_PIX_FMT_H264_SLICE:
+        GST_INFO_OBJECT (decoder, "Registering %s as H264 Decoder",
+            device->name);
+        gst_v4l2_codec_h264_dec_register (plugin, device, GST_RANK_PRIMARY + 1);
+        break;
+      default:
+        GST_FIXME_OBJECT (decoder, "%" GST_FOURCC_FORMAT " is not supported.",
+            GST_FOURCC_ARGS (fmt));
+        break;
+    }
+  }
+
+  g_object_unref (decoder);
+}
+
 static gboolean
 plugin_init (GstPlugin * plugin)
 {
+  GList *devices, *d;
+
   GST_DEBUG_CATEGORY_INIT (gstv4l2codecs_debug, "v4l2codecs", 0,
       "V4L2 CODECs general debug");
+
+  devices = gst_v4l2_codec_find_devices ();
+  for (d = devices; d; d = g_list_next (d)) {
+    GstV4l2CodecDevice *device = d->data;
+
+    if (device->function == MEDIA_ENT_F_PROC_VIDEO_DECODER)
+      register_video_decoder (plugin, device);
+  }
+
+  gst_v4l2_codec_device_list_free (devices);
   return TRUE;
 }