plugins: add support for dma_buf exports (v4l2src).

Allow v4l2src element to connected to vaapipostproc or vaapisink when
"io-mode" is set to "dmabuf-import". In practice, this is a more likely
operational mode with uvcvideo. Supporting v4lsrc with "io-mode" set
to "dmabuf" could work, but with more demanding driver or kernel reqs.

Note: with GStreamer 1.4, v4l2src (gst-plugins-good) needs to be built
with --without-libv4l2.

https://bugzilla.gnome.org/show_bug.cgi?id=743635

gst/vaapi/gstvaapipluginbase.c

@@ -24,6 +24,7 @@
 
 #include "gst/vaapi/sysdeps.h"
 #include <gst/vaapi/gstvaapisurface_drm.h>
+#include <gst/base/gstpushsrc.h>
 #include "gstvaapipluginbase.h"
 #include "gstvaapipluginutil.h"
 #include "gstvaapivideocontext.h"
@@ -392,6 +393,42 @@ gst_vaapi_plugin_base_ensure_uploader (GstVaapiPluginBase * plugin)
   return TRUE;
 }
 
+/* Checks whether the supplied pad peer element supports DMABUF sharing */
+/* XXX: this is a workaround to the absence of any proposer way to
+   specify DMABUF memory capsfeatures or bufferpool option to downstream */
+static gboolean
+has_dmabuf_capable_peer (GstVaapiPluginBase * plugin, GstPad * pad)
+{
+  GstPad *other_pad = NULL;
+  GstElement *element = NULL;
+  gchar *element_name = NULL;
+  gboolean is_dmabuf_capable = FALSE;
+  gint v;
+
+  do {
+    other_pad = gst_pad_get_peer (pad);
+    if (!other_pad)
+      break;
+
+    element = gst_pad_get_parent_element (other_pad);
+    if (!element || !GST_IS_PUSH_SRC (element))
+      break;
+
+    element_name = gst_element_get_name (element);
+    if (!element_name || sscanf (element_name, "v4l2src%d", &v) != 1)
+      break;
+
+    v = 0;
+    g_object_get (element, "io-mode", &v, NULL);
+    is_dmabuf_capable = v == 5; /* "dmabuf-import" enum value */
+  } while (0);
+
+  g_free (element_name);
+  g_clear_object (&element);
+  g_clear_object (&other_pad);
+  return is_dmabuf_capable;
+}
+
 /**
  * ensure_sinkpad_buffer_pool:
  * @plugin: a #GstVaapiPluginBase
@@ -536,6 +573,16 @@ gst_vaapi_plugin_base_propose_allocation (GstVaapiPluginBase * plugin,
       return FALSE;
     gst_query_add_allocation_pool (query, plugin->sinkpad_buffer_pool,
         plugin->sinkpad_buffer_size, 0, 0);
+
+    if (has_dmabuf_capable_peer (plugin, plugin->sinkpad)) {
+      GstStructure *const config =
+          gst_buffer_pool_get_config (plugin->sinkpad_buffer_pool);
+
+      gst_buffer_pool_config_add_option (config,
+          GST_BUFFER_POOL_OPTION_DMABUF_MEMORY);
+      if (!gst_buffer_pool_set_config (plugin->sinkpad_buffer_pool, config))
+        goto error_pool_config;
+    }
   }
 
   gst_query_add_allocation_meta (query, GST_VAAPI_VIDEO_META_API_TYPE, NULL);
@@ -548,6 +595,11 @@ error_no_caps:
     GST_ERROR ("no caps specified");
     return FALSE;
   }
+error_pool_config:
+  {
+    GST_ERROR ("failed to reset buffer pool config");
+    return FALSE;
+  }
 }
 #endif
 

gst/vaapi/gstvaapivideobufferpool.c

@@ -46,10 +46,12 @@ struct _GstVaapiVideoBufferPoolPrivate
   GstVideoInfo video_info[2];
   guint video_info_index;
   GstAllocator *allocator;
+  GstVideoInfo alloc_info;
   GstVaapiDisplay *display;
   guint has_video_meta:1;
   guint has_video_alignment:1;
   guint has_texture_upload_meta:1;
+  guint use_dmabuf_memory:1;
 };
 
 #define GST_VAAPI_VIDEO_BUFFER_POOL_GET_PRIVATE(obj) \
@@ -105,8 +107,7 @@ gst_vaapi_video_buffer_pool_get_property (GObject * object, guint prop_id,
 static void
 fill_video_alignment (GstVaapiVideoBufferPool * pool, GstVideoAlignment * align)
 {
-  GstVideoInfo *const vip =
+  GstVideoInfo *const vip = &pool->priv->alloc_info;
-      &GST_VAAPI_VIDEO_ALLOCATOR_CAST (pool->priv->allocator)->image_info;
   guint i;
 
   gst_video_alignment_reset (align);
@@ -140,26 +141,48 @@ gst_vaapi_video_buffer_pool_set_config (GstBufferPool * pool,
   GstVideoInfo *const new_vip = &priv->video_info[!priv->video_info_index];
   GstVideoAlignment align;
   GstAllocator *allocator;
-  gboolean changed_caps;
+  gboolean changed_caps, use_dmabuf_memory;
 
   if (!gst_buffer_pool_config_get_params (config, &caps, NULL, NULL, NULL))
     goto error_invalid_config;
   if (!caps || !gst_video_info_from_caps (new_vip, caps))
     goto error_no_caps;
 
+  use_dmabuf_memory = gst_buffer_pool_config_has_option (config,
+      GST_BUFFER_POOL_OPTION_DMABUF_MEMORY);
+  if (priv->use_dmabuf_memory != use_dmabuf_memory) {
+    priv->use_dmabuf_memory = use_dmabuf_memory;
+    g_clear_object (&priv->allocator);
+  }
+
   changed_caps = !priv->allocator ||
       GST_VIDEO_INFO_FORMAT (cur_vip) != GST_VIDEO_INFO_FORMAT (new_vip) ||
       GST_VIDEO_INFO_WIDTH (cur_vip) != GST_VIDEO_INFO_WIDTH (new_vip) ||
       GST_VIDEO_INFO_HEIGHT (cur_vip) != GST_VIDEO_INFO_HEIGHT (new_vip);
 
   if (changed_caps) {
-    allocator = gst_vaapi_video_allocator_new (priv->display, new_vip, 0);
+    const GstVideoInfo *alloc_vip;
+    guint flags = 0;
+
+    if (use_dmabuf_memory) {
+      /* XXX: also needs fixed strides/offsets */
+      flags |= GST_VAAPI_SURFACE_ALLOC_FLAG_LINEAR_STORAGE;
+      allocator =
+          gst_vaapi_dmabuf_allocator_new (priv->display, new_vip, flags);
+    } else {
+      allocator = gst_vaapi_video_allocator_new (priv->display, new_vip, 0);
+    }
     if (!allocator)
       goto error_create_allocator;
     gst_object_replace ((GstObject **) & priv->allocator,
         GST_OBJECT_CAST (allocator));
     gst_object_unref (allocator);
     priv->video_info_index ^= 1;
+
+    alloc_vip = gst_allocator_get_vaapi_video_info (allocator, NULL);
+    if (!alloc_vip)
+      goto error_create_allocator_info;
+    priv->alloc_info = *alloc_vip;
   }
 
   if (!gst_buffer_pool_config_has_option (config,
@@ -199,6 +222,11 @@ error_create_allocator:
     GST_ERROR ("failed to create GstVaapiVideoAllocator object");
     return FALSE;
   }
+error_create_allocator_info:
+  {
+    GST_ERROR ("failed to create GstVaapiVideoAllocator `video-info'");
+    return FALSE;
+  }
 error_no_vaapi_video_meta_option:
   {
     GST_ERROR ("no GstVaapiVideoMeta option");
@@ -235,15 +263,17 @@ gst_vaapi_video_buffer_pool_alloc_buffer (GstBufferPool * pool,
   if (!buffer)
     goto error_create_buffer;
 
-  mem = gst_vaapi_video_memory_new (priv->allocator, meta);
+  if (priv->use_dmabuf_memory)
+    mem = gst_vaapi_dmabuf_memory_new (priv->allocator, meta);
+  else
+    mem = gst_vaapi_video_memory_new (priv->allocator, meta);
   if (!mem)
     goto error_create_memory;
   gst_vaapi_video_meta_replace (&meta, NULL);
   gst_buffer_append_memory (buffer, mem);
 
   if (priv->has_video_meta) {
-    GstVideoInfo *const vip =
+    GstVideoInfo *const vip = &priv->alloc_info;
-        &GST_VAAPI_VIDEO_ALLOCATOR_CAST (priv->allocator)->image_info;
     GstVideoMeta *vmeta;
 
     vmeta = gst_buffer_add_video_meta_full (buffer, 0,
@@ -251,9 +281,13 @@ gst_vaapi_video_buffer_pool_alloc_buffer (GstBufferPool * pool,
         GST_VIDEO_INFO_HEIGHT (vip), GST_VIDEO_INFO_N_PLANES (vip),
         &GST_VIDEO_INFO_PLANE_OFFSET (vip, 0),
         &GST_VIDEO_INFO_PLANE_STRIDE (vip, 0));
-    vmeta->map = gst_video_meta_map_vaapi_memory;
+
-    vmeta->unmap = gst_video_meta_unmap_vaapi_memory;
+    if (GST_VAAPI_IS_VIDEO_MEMORY (mem)) {
+      vmeta->map = gst_video_meta_map_vaapi_memory;
+      vmeta->unmap = gst_video_meta_unmap_vaapi_memory;
+    }
   }
+
 #if GST_CHECK_VERSION(1,1,0) && USE_GLX
   if (priv->has_texture_upload_meta)
     gst_buffer_add_texture_upload_meta (buffer);
@@ -295,7 +329,8 @@ gst_vaapi_video_buffer_pool_reset_buffer (GstBufferPool * pool,
   GstMemory *const mem = gst_buffer_peek_memory (buffer, 0);
 
   /* Release the underlying surface proxy */
-  gst_vaapi_video_memory_reset_surface (GST_VAAPI_VIDEO_MEMORY_CAST (mem));
+  if (GST_VAAPI_IS_VIDEO_MEMORY (mem))
+    gst_vaapi_video_memory_reset_surface (GST_VAAPI_VIDEO_MEMORY_CAST (mem));
 
   GST_BUFFER_POOL_CLASS (gst_vaapi_video_buffer_pool_parent_class)->reset_buffer
       (pool, buffer);
@@ -344,6 +379,7 @@ gst_vaapi_video_buffer_pool_init (GstVaapiVideoBufferPool * pool)
 
   gst_video_info_init (&priv->video_info[0]);
   gst_video_info_init (&priv->video_info[1]);
+  gst_video_info_init (&priv->alloc_info);
 }
 
 GstBufferPool *

gst/vaapi/gstvaapivideobufferpool.h

@@ -69,6 +69,17 @@ typedef struct _GstVaapiVideoBufferPoolPrivate GstVaapiVideoBufferPoolPrivate;
   "GstBufferPoolOptionVideoGLTextureUploadMeta"
 #endif
 
+/**
+ * GST_BUFFER_POOL_OPTION_DMABUF_MEMORY:
+ *
+ * An option that can be activated on bufferpool to request dmabuf
+ * handles on buffers from the pool.
+ */
+#ifndef GST_BUFFER_POOL_OPTION_DMABUF_MEMORY
+#define GST_BUFFER_POOL_OPTION_DMABUF_MEMORY \
+  "GstBufferPoolOptionDMABUFMemory"
+#endif
+
 /**
  * GstVaapiVideoBufferPoolAcquireFlags:
  * @GST_VAAPI_VIDEO_BUFFER_POOL_ACQUIRE_FLAG_NO_ALLOC: option to

gst/vaapi/gstvaapivideomemory.c

@@ -21,6 +21,7 @@
  */
 
 #include "gst/vaapi/sysdeps.h"
+#include <gst/vaapi/gstvaapisurface_drm.h>
 #include <gst/vaapi/gstvaapisurfacepool.h>
 #include <gst/vaapi/gstvaapiimagepool.h>
 #include "gstvaapivideomemory.h"
@@ -298,6 +299,8 @@ gst_vaapi_video_memory_new (GstAllocator * base_allocator,
   const GstVideoInfo *vip;
   GstVaapiVideoMemory *mem;
 
+  g_return_val_if_fail (GST_VAAPI_IS_VIDEO_ALLOCATOR (allocator), NULL);
+
   mem = g_slice_new (GstVaapiVideoMemory);
   if (!mem)
     return NULL;
@@ -725,6 +728,9 @@ gst_vaapi_video_allocator_new (GstVaapiDisplay * display,
       &allocator->image_info);
   if (!allocator->image_pool)
     goto error_create_image_pool;
+
+  gst_allocator_set_vaapi_video_info (GST_ALLOCATOR_CAST (allocator),
+      &allocator->image_info, 0);
   return GST_ALLOCATOR_CAST (allocator);
 
   /* ERRORS */
@@ -741,3 +747,260 @@ error_create_image_pool:
     return NULL;
   }
 }
+
+/* ------------------------------------------------------------------------ */
+/* --- GstVaapiDmaBufMemory                                             --- */
+/* ------------------------------------------------------------------------ */
+
+#define GST_VAAPI_BUFFER_PROXY_QUARK gst_vaapi_buffer_proxy_quark_get ()
+static GQuark
+gst_vaapi_buffer_proxy_quark_get (void)
+{
+  static gsize g_quark;
+
+  if (g_once_init_enter (&g_quark)) {
+    gsize quark = (gsize) g_quark_from_static_string ("GstVaapiBufferProxy");
+    g_once_init_leave (&g_quark, quark);
+  }
+  return g_quark;
+}
+
+GstMemory *
+gst_vaapi_dmabuf_memory_new (GstAllocator * allocator, GstVaapiVideoMeta * meta)
+{
+  GstMemory *mem;
+  GstVaapiDisplay *display;
+  GstVaapiSurface *surface;
+  GstVaapiSurfaceProxy *proxy;
+  GstVaapiBufferProxy *dmabuf_proxy;
+  const GstVideoInfo *vip;
+  guint flags;
+
+  g_return_val_if_fail (allocator != NULL, NULL);
+  g_return_val_if_fail (meta != NULL, NULL);
+
+  vip = gst_allocator_get_vaapi_video_info (allocator, &flags);
+  if (!vip)
+    return NULL;
+
+  display = gst_vaapi_video_meta_get_display (meta);
+  if (!meta)
+    return NULL;
+
+  surface = gst_vaapi_surface_new_full (display, vip, flags);
+  if (!surface)
+    goto error_create_surface;
+
+  proxy = gst_vaapi_surface_proxy_new (surface);
+  if (!proxy)
+    goto error_create_surface_proxy;
+
+  dmabuf_proxy = gst_vaapi_surface_get_dma_buf_handle (surface);
+  gst_vaapi_object_unref (surface);
+  if (!dmabuf_proxy)
+    goto error_create_dmabuf_proxy;
+
+  gst_vaapi_video_meta_set_surface_proxy (meta, proxy);
+  gst_vaapi_surface_proxy_unref (proxy);
+
+  mem = gst_dmabuf_allocator_alloc (allocator,
+      gst_vaapi_buffer_proxy_get_handle (dmabuf_proxy),
+      gst_vaapi_buffer_proxy_get_size (dmabuf_proxy));
+  if (!mem)
+    goto error_create_dmabuf_memory;
+
+  gst_mini_object_set_qdata (GST_MINI_OBJECT_CAST (mem),
+      GST_VAAPI_BUFFER_PROXY_QUARK, dmabuf_proxy,
+      (GDestroyNotify) gst_vaapi_buffer_proxy_unref);
+  return mem;
+
+  /* ERRORS */
+error_create_surface:
+  {
+    GST_ERROR ("failed to create VA surface (format:%s size:%ux%u)",
+        gst_video_format_to_string (GST_VIDEO_INFO_FORMAT (vip)),
+        GST_VIDEO_INFO_WIDTH (vip), GST_VIDEO_INFO_HEIGHT (vip));
+    return NULL;
+  }
+error_create_surface_proxy:
+  {
+    GST_ERROR ("failed to create VA surface proxy");
+    gst_vaapi_object_unref (surface);
+    return NULL;
+  }
+error_create_dmabuf_proxy:
+  {
+    GST_ERROR ("failed to export VA surface to DMABUF");
+    gst_vaapi_surface_proxy_unref (proxy);
+    return NULL;
+  }
+error_create_dmabuf_memory:
+  {
+    GST_ERROR ("failed to create DMABUF memory");
+    gst_vaapi_buffer_proxy_unref (dmabuf_proxy);
+    return NULL;
+  }
+}
+
+/* ------------------------------------------------------------------------ */
+/* --- GstVaapiDmaBufAllocator                                          --- */
+/* ------------------------------------------------------------------------ */
+
+GstAllocator *
+gst_vaapi_dmabuf_allocator_new (GstVaapiDisplay * display,
+    const GstVideoInfo * vip, guint flags)
+{
+  GstAllocator *allocator = NULL;
+  GstVaapiSurface *surface = NULL;
+  GstVaapiImage *image = NULL;
+  GstVideoInfo alloc_info;
+
+  g_return_val_if_fail (display != NULL, NULL);
+  g_return_val_if_fail (vip != NULL, NULL);
+
+  do {
+    surface = gst_vaapi_surface_new_full (display, vip, flags);
+    if (!surface)
+      break;
+
+    image = gst_vaapi_surface_derive_image (surface);
+    if (!image || !gst_vaapi_image_map (image))
+      break;
+
+    gst_video_info_set_format (&alloc_info, GST_VIDEO_INFO_FORMAT (vip),
+        GST_VIDEO_INFO_WIDTH (vip), GST_VIDEO_INFO_HEIGHT (vip));
+    gst_video_info_update_from_image (&alloc_info, image);
+    gst_vaapi_image_unmap (image);
+
+    allocator = gst_dmabuf_allocator_new ();
+    if (!allocator)
+      break;
+    gst_allocator_set_vaapi_video_info (allocator, &alloc_info, flags);
+  } while (0);
+
+  gst_vaapi_object_replace (&image, NULL);
+  gst_vaapi_object_replace (&surface, NULL);
+  return allocator;
+}
+
+/* ------------------------------------------------------------------------ */
+/* --- GstVaapiVideoInfo = { GstVideoInfo, flags }                      --- */
+/* ------------------------------------------------------------------------ */
+
+static GstVideoInfo *
+gst_vaapi_video_info_copy (const GstVideoInfo * vip)
+{
+  GstVideoInfo *out_vip;
+
+  out_vip = g_slice_new (GstVideoInfo);
+  if (!out_vip)
+    return NULL;
+
+  gst_video_info_init (out_vip);
+  *out_vip = *vip;
+  return out_vip;
+}
+
+static void
+gst_vaapi_video_info_free (GstVideoInfo * vip)
+{
+  g_slice_free (GstVideoInfo, vip);
+}
+
+#define GST_VAAPI_TYPE_VIDEO_INFO gst_vaapi_video_info_get_type ()
+static GType
+gst_vaapi_video_info_get_type (void)
+{
+  static gsize g_type;
+
+  if (g_once_init_enter (&g_type)) {
+    GType type;
+    type = g_boxed_type_register_static ("GstVaapiVideoInfo",
+        (GBoxedCopyFunc) gst_vaapi_video_info_copy,
+        (GBoxedFreeFunc) gst_vaapi_video_info_free);
+    g_once_init_leave (&g_type, type);
+  }
+  return (GType) g_type;
+}
+
+#define GST_VAAPI_VIDEO_INFO_QUARK gst_vaapi_video_info_quark_get ()
+static GQuark
+gst_vaapi_video_info_quark_get (void)
+{
+  static gsize g_quark;
+
+  if (g_once_init_enter (&g_quark)) {
+    gsize quark = (gsize) g_quark_from_static_string ("GstVaapiVideoInfo");
+    g_once_init_leave (&g_quark, quark);
+  }
+  return g_quark;
+}
+
+#define INFO_QUARK info_quark_get ()
+static GQuark
+info_quark_get (void)
+{
+  static gsize g_quark;
+
+  if (g_once_init_enter (&g_quark)) {
+    gsize quark = (gsize) g_quark_from_static_string ("info");
+    g_once_init_leave (&g_quark, quark);
+  }
+  return g_quark;
+}
+
+#define FLAGS_QUARK flags_quark_get ()
+static GQuark
+flags_quark_get (void)
+{
+  static gsize g_quark;
+
+  if (g_once_init_enter (&g_quark)) {
+    gsize quark = (gsize) g_quark_from_static_string ("flags");
+    g_once_init_leave (&g_quark, quark);
+  }
+  return g_quark;
+}
+
+const GstVideoInfo *
+gst_allocator_get_vaapi_video_info (GstAllocator * allocator,
+    guint * out_flags_ptr)
+{
+  const GstStructure *structure;
+  const GValue *value;
+
+  g_return_val_if_fail (GST_IS_ALLOCATOR (allocator), NULL);
+
+  structure =
+      g_object_get_qdata (G_OBJECT (allocator), GST_VAAPI_VIDEO_INFO_QUARK);
+  if (!structure)
+    return NULL;
+
+  if (out_flags_ptr) {
+    value = gst_structure_id_get_value (structure, FLAGS_QUARK);
+    if (!value)
+      return NULL;
+    *out_flags_ptr = g_value_get_uint (value);
+  }
+
+  value = gst_structure_id_get_value (structure, INFO_QUARK);
+  if (!value)
+    return NULL;
+  return g_value_get_boxed (value);
+}
+
+gboolean
+gst_allocator_set_vaapi_video_info (GstAllocator * allocator,
+    const GstVideoInfo * vip, guint flags)
+{
+  g_return_val_if_fail (GST_IS_ALLOCATOR (allocator), FALSE);
+  g_return_val_if_fail (vip != NULL, FALSE);
+
+  g_object_set_qdata_full (G_OBJECT (allocator), GST_VAAPI_VIDEO_INFO_QUARK,
+      gst_structure_new_id (GST_VAAPI_VIDEO_INFO_QUARK,
+          INFO_QUARK, GST_VAAPI_TYPE_VIDEO_INFO, vip,
+          FLAGS_QUARK, G_TYPE_UINT, flags, NULL),
+      (GDestroyNotify) gst_structure_free);
+
+  return TRUE;
+}

gst/vaapi/gstvaapivideomemory.h

@@ -28,6 +28,9 @@
 #include <gst/vaapi/gstvaapidisplay.h>
 #include <gst/vaapi/gstvaapivideopool.h>
 #include "gstvaapivideometa.h"
+#if GST_CHECK_VERSION(1,1,0)
+#include <gst/allocators/allocators.h>
+#endif
 
 G_BEGIN_DECLS
 
@@ -113,6 +116,10 @@ struct _GstVaapiVideoMemory
   gboolean use_direct_rendering;
 };
 
+G_GNUC_INTERNAL
+GQuark
+gst_vaapi_video_memory_quark_get (void);
+
 G_GNUC_INTERNAL
 GstMemory *
 gst_vaapi_video_memory_new (GstAllocator * allocator, GstVaapiVideoMeta * meta);
@@ -189,6 +196,32 @@ GstAllocator *
 gst_vaapi_video_allocator_new (GstVaapiDisplay * display,
     const GstVideoInfo * vip, guint flags);
 
+/* ------------------------------------------------------------------------ */
+/* --- GstVaapiDmaBufMemory                                             --- */
+/* ------------------------------------------------------------------------ */
+
+G_GNUC_INTERNAL
+GstMemory *
+gst_vaapi_dmabuf_memory_new (GstAllocator * allocator,
+    GstVaapiVideoMeta * meta);
+
+/* ------------------------------------------------------------------------ */
+/* --- GstVaapiDmaBufAllocator                                          --- */
+/* ------------------------------------------------------------------------ */
+
+G_GNUC_INTERNAL
+GstAllocator *
+gst_vaapi_dmabuf_allocator_new (GstVaapiDisplay * display,
+    const GstVideoInfo * vip, guint flags);
+
+const GstVideoInfo *
+gst_allocator_get_vaapi_video_info (GstAllocator * allocator,
+    guint * out_flags_ptr);
+
+gboolean
+gst_allocator_set_vaapi_video_info (GstAllocator * allocator,
+    const GstVideoInfo * vip, guint flags);
+
 G_END_DECLS
 
 #endif /* GST_VAAPI_VIDEO_MEMORY_H */