Always copy buffers by default (handle safer with bugged drivers) and added a property to make it possible to use mma...

Original commit message from CVS:
Always copy buffers by default (handle safer with bugged drivers) and added a property to make it possible to use mmap effectively (no copy if possible) when application wants to. Fixes: #480557.

ChangeLog

@@ -1,3 +1,14 @@
+2007-11-15  Edgard Lima  <edgard.lima@indt.org.br>
+
+	* sys/v4l2/gstv4l2src.c: (gst_v4l2src_class_init),
+	(gst_v4l2src_init), (gst_v4l2src_set_property),
+	(gst_v4l2src_get_property):
+	* sys/v4l2/gstv4l2src.h:
+	* sys/v4l2/v4l2src_calls.c: (gst_v4l2src_grab_frame):
+	  Always copy buffers by default (handle safer with bugged drivers)
+	  and added a property to make it possible to use mmap effectively (no
+	  copy if possible) when application wants to. Fixes: #480557.
+
 2007-11-14  Tim-Philipp Müller  <tim at centricular dot net>
 
 	* gst/id3demux/id3tags.c:

sys/v4l2/gstv4l2src.c

@@ -68,11 +68,14 @@ GST_ELEMENT_DETAILS ("Video (video4linux2/raw) Source",
 GST_DEBUG_CATEGORY (v4l2src_debug);
 #define GST_CAT_DEFAULT v4l2src_debug
 
+#define DEFAULT_PROP_ALWAYS_COPY        TRUE
+
 enum
 {
   PROP_0,
   V4L2_STD_OBJECT_PROPS,
-  PROP_QUEUE_SIZE
+  PROP_QUEUE_SIZE,
+  PROP_ALWAYS_COPY
 };
 
 static const guint32 gst_v4l2_formats[] = {
@@ -289,6 +292,10 @@ gst_v4l2src_class_init (GstV4l2SrcClass * klass)
           "Number of buffers to be enqueud in the driver",
           GST_V4L2_MIN_BUFFERS, GST_V4L2_MAX_BUFFERS, GST_V4L2_MIN_BUFFERS,
           G_PARAM_READWRITE));
+  g_object_class_install_property (gobject_class, PROP_ALWAYS_COPY,
+      g_param_spec_boolean ("always-copy", "Always Copy",
+          "If the buffer will or not be used directly from mmap",
+          DEFAULT_PROP_ALWAYS_COPY, G_PARAM_READWRITE));
 
   basesrc_class->get_caps = GST_DEBUG_FUNCPTR (gst_v4l2src_get_caps);
   basesrc_class->set_caps = GST_DEBUG_FUNCPTR (gst_v4l2src_set_caps);
@@ -310,6 +317,8 @@ gst_v4l2src_init (GstV4l2Src * v4l2src, GstV4l2SrcClass * klass)
   /* number of buffers requested */
   v4l2src->num_buffers = GST_V4L2_MIN_BUFFERS;
 
+  v4l2src->always_copy = DEFAULT_PROP_ALWAYS_COPY;
+
   v4l2src->formats = NULL;
 
   v4l2src->is_capturing = FALSE;
@@ -356,6 +365,9 @@ gst_v4l2src_set_property (GObject * object,
       case PROP_QUEUE_SIZE:
         v4l2src->num_buffers = g_value_get_uint (value);
         break;
+      case PROP_ALWAYS_COPY:
+        v4l2src->always_copy = g_value_get_boolean (value);
+        break;
       default:
         G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
         break;
@@ -376,6 +388,9 @@ gst_v4l2src_get_property (GObject * object,
       case PROP_QUEUE_SIZE:
         g_value_set_uint (value, v4l2src->num_buffers);
         break;
+      case PROP_ALWAYS_COPY:
+        g_value_set_boolean (value, v4l2src->always_copy);
+        break;
       default:
         G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
         break;

sys/v4l2/gstv4l2src.h

@@ -101,6 +101,9 @@ struct _GstV4l2Src
   gboolean use_mmap;
   guint32 frame_byte_size;
 
+  /* if the buffer will be or not used from directly mmap */
+  gboolean always_copy;
+
   /* True if we want to stop */
   gboolean quit;
   gboolean is_capturing;

sys/v4l2/v4l2src_calls.c

@@ -954,26 +954,16 @@ gst_v4l2src_grab_frame (GstV4l2Src * v4l2src, GstBuffer ** buf)
     }
   }
 
-  do {
+  g_mutex_lock (v4l2src->pool->lock);
 
-    g_mutex_lock (v4l2src->pool->lock);
+  index = buffer.index;
 
-    index = buffer.index;
+  /* get our GstBuffer with that index from the pool, if the buffer was
-
+   * outstanding we have a serious problem. */
-    /* get our GstBuffer with that index from the pool, if the buffer was
+  pool_buffer = GST_BUFFER (v4l2src->pool->buffers[index]);
-     * outstanding we have a serious problem. */
-    pool_buffer = GST_BUFFER (v4l2src->pool->buffers[index]);
-
-    if (pool_buffer == NULL) {
-      g_mutex_unlock (v4l2src->pool->lock);
-      g_usleep (20000);         /* wait 20 miliseconds */
-      /* FIXME: we need a exit condition here */
-    } else {
-      break;
-    }
-
-  } while (TRUE);
 
+  if (pool_buffer == NULL)
+    goto no_buffer;
 
   GST_LOG_OBJECT (v4l2src, "grabbed buffer %p at index %d", pool_buffer, index);
 
@@ -982,7 +972,8 @@ gst_v4l2src_grab_frame (GstV4l2Src * v4l2src, GstBuffer ** buf)
   v4l2src->pool->num_live_buffers++;
   /* if we are handing out the last buffer in the pool, we need to make a
    * copy and bring the buffer back in the pool. */
-  need_copy = v4l2src->pool->num_live_buffers == v4l2src->pool->buffer_count;
+  need_copy = v4l2src->always_copy
+      || (v4l2src->pool->num_live_buffers == v4l2src->pool->buffer_count);
 
   g_mutex_unlock (v4l2src->pool->lock);
 
@@ -1020,6 +1011,7 @@ gst_v4l2src_grab_frame (GstV4l2Src * v4l2src, GstBuffer ** buf)
 
   if (G_UNLIKELY (need_copy)) {
     *buf = gst_buffer_copy (pool_buffer);
+    GST_BUFFER_FLAG_UNSET (*buf, GST_BUFFER_FLAG_READONLY);
     /* this will requeue */
     gst_buffer_unref (pool_buffer);
   } else {
@@ -1059,7 +1051,7 @@ too_many_trials:
             NUM_TRIALS, v4l2src->v4l2object->videodev, g_strerror (errno)));
     return GST_FLOW_ERROR;
   }
-#if 0
+no_buffer:
   {
     GST_ELEMENT_ERROR (v4l2src, RESOURCE, FAILED,
         (_("Failed trying to get video frames from device '%s'."),
@@ -1068,7 +1060,6 @@ too_many_trials:
     g_mutex_unlock (v4l2src->pool->lock);
     return GST_FLOW_ERROR;
   }
-#endif
 /*
 qbuf_failed:
   {