[clutter-gst] video-sink: keep GstBuffer around until the next frame

[Lionel Landwerlin <llandwerlin src gnome org>]

commit b7eb4d54e863a96e231d11668d5e84613bba3f8a
Author: Lionel Landwerlin <llandwerlin gmail com>
Date:   Thu Jun 26 21:56:21 2014 +0100

    video-sink: keep GstBuffer around until the next frame
    
    We're working around the blitter here...
    
    The only supported GL texture upload plugin (as far as I know) is
    vaapidecode at the moment. This plugin has a fairly slow upload path :
    
    vaapisurface -> Pixmap -> GL texture
    
    This can take some time and the last part is currently not
    synchronized. Therefore it leads to tearing. This patch tries to keep
    the buffer around to prevent that but it's not perfect.

 clutter-gst/clutter-gst-video-sink.c |   36 ++++++++++++++++++++++++++-------
 1 files changed, 28 insertions(+), 8 deletions(-)
---
diff --git a/clutter-gst/clutter-gst-video-sink.c b/clutter-gst/clutter-gst-video-sink.c
index ed9be81..b81731c 100644
--- a/clutter-gst/clutter-gst-video-sink.c
+++ b/clutter-gst/clutter-gst-video-sink.c
@@ -1259,6 +1259,8 @@ clutter_gst_rgb32_upload (ClutterGstVideoSink *sink,
   }
 }
 
+static CoglUserDataKey gl_upload_texture_private_key;
+#define MAX_ALLOCATED_GL_TEXTURES (1)
 
 static gboolean
 clutter_gst_rgb32_upload_gl (ClutterGstVideoSink *sink,
@@ -1266,6 +1268,7 @@ clutter_gst_rgb32_upload_gl (ClutterGstVideoSink *sink,
 {
   ClutterGstVideoSinkPrivate *priv = sink->priv;
   GstVideoGLTextureUploadMeta *upload_meta;
+  gint i;
   guint gl_handle[1];
 
   //clear_frame_textures (sink);
@@ -1284,16 +1287,33 @@ clutter_gst_rgb32_upload_gl (ClutterGstVideoSink *sink,
 
   if (priv->frame[0] == NULL)
     {
-      priv->frame[0] = COGL_TEXTURE (cogl_texture_2d_new_with_size (priv->ctx,
-                                                                    priv->info.width,
-                                                                    priv->info.height));
-      cogl_texture_set_components (priv->frame[0], COGL_TEXTURE_COMPONENTS_RGBA);
-
-      if (!cogl_texture_allocate (priv->frame[0], NULL)) {
-        GST_WARNING ("Couldn't allocate cogl texture");
-        return FALSE;
+      for (i = 0; i < MAX_ALLOCATED_GL_TEXTURES; i++) {
+        priv->frame[i] = COGL_TEXTURE (cogl_texture_2d_new_with_size (priv->ctx,
+                                                                      priv->info.width,
+                                                                      priv->info.height));
+        cogl_texture_set_components (priv->frame[i], COGL_TEXTURE_COMPONENTS_RGBA);
+
+        if (!cogl_texture_allocate (priv->frame[i], NULL)) {
+          GST_WARNING ("Couldn't allocate cogl texture");
+          return FALSE;
+        }
       }
     }
+  else
+    {
+      CoglTexture *tmp;
+
+      tmp = priv->frame[0];
+      for (i = 0; i < MAX_ALLOCATED_GL_TEXTURES - 1; i++)
+        priv->frame[i] = priv->frame[i + 1];
+      priv->frame[MAX_ALLOCATED_GL_TEXTURES - 1] = tmp;
+    }
+
+  cogl_object_set_user_data (COGL_OBJECT (priv->frame[0]),
+                             &gl_upload_texture_private_key,
+                             gst_buffer_ref (buffer),
+                             (CoglUserDataDestroyCallback) gst_buffer_unref);
+
 
   if (!cogl_texture_get_gl_texture (priv->frame[0], &gl_handle[0], NULL)) {
     GST_WARNING ("Couldn't get gl texture");