glememory: only store and act on the map flags on first/last map/unmap

Anytime else, we have no idea how to match up map and unmaps.
We also don't know exactly how the calling code is using us.
Also fixes the case where we're trying to transfer while someone else
is accessing our data pointer or texture resulting in mismatched video
frames.

https://bugzilla.gnome.org/show_bug.cgi?id=744839

diff --git a/gst-libs/gst/gl/gstglmemory.c b/gst-libs/gst/gl/gstglmemory.c
index a4dbb5c..e9e7791 100644 (file)
--- a/gst-libs/gst/gl/gstglmemory.c
+++ b/gst-libs/gst/gl/gstglmemory.c
@@ -859,7 +859,9 @@ _gl_mem_map (GstGLMemory * gl_mem, gsize maxsize, GstMapFlags flags)
     data = gl_mem->data;
   }
 
-  gl_mem->map_flags = flags;
+  /* only store the first map flags, subsequent maps must be a subset of this */
+  if (gl_mem->map_count++ == 0)
+    gl_mem->map_flags = flags;
 
   g_mutex_unlock (&gl_mem->lock);
 
@@ -882,13 +884,15 @@ _gl_mem_unmap (GstGLMemory * gl_mem)
 {
   g_mutex_lock (&gl_mem->lock);
 
-  if (gl_mem->map_flags & GST_MAP_WRITE) {
-    if (!(gl_mem->map_flags & GST_MAP_GL))
+  if (gl_mem->map_count <= 1 && gl_mem->map_flags & GST_MAP_WRITE) {
+    if (!(gl_mem->map_flags & GST_MAP_GL)) {
       gst_gl_context_thread_add (gl_mem->context,
           (GstGLContextThreadFunc) _transfer_upload, gl_mem);
+    }
   }
 
-  gl_mem->map_flags = 0;
+  if (--gl_mem->map_count <= 0)
+    gl_mem->map_flags = 0;
 
   g_mutex_unlock (&gl_mem->lock);
 }

diff --git a/gst-libs/gst/gl/gstglmemory.h b/gst-libs/gst/gl/gstglmemory.h
index 7dad0aa..ec23577 100644 (file)
--- a/gst-libs/gst/gl/gstglmemory.h
+++ b/gst-libs/gst/gl/gstglmemory.h
@@ -103,6 +103,7 @@ struct _GstGLMemory
   guint                 tex_width;
   guint                 transfer_pbo;
   GstMapFlags           map_flags;
+  guint                 map_count;
 
   GMutex                lock;
 };