v4l2object: Improved decide allocation

Improve decide allocation so it properly configure both local and downstream
buffer pools. Also read back the pool config if it was changed to to driver
limitations.

sys/v4l2/gstv4l2object.c

@@ -3042,7 +3042,8 @@ gst_v4l2_object_decide_allocation (GstV4l2Object * obj, GstQuery * query)
 {
   GstCaps *caps;
   GstBufferPool *pool;
-  guint size, min, max;
+  GstStructure *config;
+  guint size, min, max, extra = 0;
   gboolean update;
   gboolean has_video_meta, has_crop_meta;
   gboolean can_use_own_pool;
@@ -3087,13 +3088,11 @@ gst_v4l2_object_decide_allocation (GstV4l2Object * obj, GstQuery * query)
     GST_DEBUG_OBJECT (obj->element, "driver require a minimum of %d buffers",
         ctl.value);
     obj->min_buffers_for_capture = ctl.value;
-    min += ctl.value;
+    extra += ctl.value;
+  } else {
+    obj->min_buffers_for_capture = 0;
   }
 
-  /* Request a bigger max, if one was suggested but it's too small */
-  if (max != 0)
-    max = MAX (min, max);
-
   has_video_meta =
       gst_query_find_allocation_meta (query, GST_VIDEO_META_API_TYPE, NULL);
   has_crop_meta =
@@ -3133,7 +3132,6 @@ gst_v4l2_object_decide_allocation (GstV4l2Object * obj, GstQuery * query)
           gst_object_unref (pool);
         pool = obj->pool;
         size = obj->sizeimage;
-        max = 0;
         GST_DEBUG_OBJECT (obj->element,
             "streaming mode: using our own pool %" GST_PTR_FORMAT, pool);
       } else if (pool) {
@@ -3149,19 +3147,55 @@ gst_v4l2_object_decide_allocation (GstV4l2Object * obj, GstQuery * query)
       break;
   }
 
-  /* Size field is mandatory and we have no size if now using our own pool and
-   * downstream didn't provide one. */
-  if (size == 0) {
-    GstVideoInfo info;
+  if (size == 0)
+    goto no_size;
+
+  /* Request a bigger max, if one was suggested but it's too small */
+  if (max != 0)
+    max = MAX (min, max);
+
+  /* First step, configure our own pool */
+
+  /* If already configured/active, skip it */
+  /* FIXME not entirely correct, See bug 728268 */
+  if (gst_buffer_pool_is_active (obj->pool))
+    goto setup_other_pool;
 
-    gst_video_info_init (&info);
-    gst_video_info_from_caps (&info, caps);
+  config = gst_buffer_pool_get_config (obj->pool);
 
-    size = GST_VIDEO_INFO_SIZE (&info);
+  if (obj->need_video_meta) {
+    GST_DEBUG_OBJECT (pool, "activate Video Meta");
+    gst_buffer_pool_config_add_option (config,
+        GST_BUFFER_POOL_OPTION_VIDEO_META);
   }
 
-  if (pool) {
-    GstStructure *config;
+  if (obj->need_crop_meta) {
+    GST_DEBUG_OBJECT (pool, "activate VideoCrop Meta");
+    gst_buffer_pool_config_add_option (config,
+        GST_V4L2_BUFFER_POOL_OPTION_CROP_META);
+  }
+
+  gst_buffer_pool_config_set_params (config, caps, size, min + extra, 0);
+
+  GST_DEBUG_OBJECT (pool, "setting config %" GST_PTR_FORMAT, config);
+
+  /* Our pool often need to adjust the value */
+  if (!gst_buffer_pool_set_config (obj->pool, config)) {
+    config = gst_buffer_pool_get_config (obj->pool);
+
+    GST_DEBUG_OBJECT (pool, "config changed to %" GST_PTR_FORMAT, config);
+
+    /* our pool will adjust the maximum buffer, which we are fine with */
+
+    if (!gst_buffer_pool_set_config (obj->pool, config))
+      goto config_failed;
+  }
+
+setup_other_pool:
+  /* Now configure the other pool if different */
+  if (pool && obj->pool != pool) {
+    if (gst_buffer_pool_is_active (obj->pool))
+      goto done;
 
     config = gst_buffer_pool_get_config (pool);
     gst_buffer_pool_config_set_params (config, caps, size, min, max);
@@ -3173,9 +3207,11 @@ gst_v4l2_object_decide_allocation (GstV4l2Object * obj, GstQuery * query)
           GST_BUFFER_POOL_OPTION_VIDEO_META);
     }
 
+    /* TODO check return value, validate changes and confirm */
     gst_buffer_pool_set_config (pool, config);
   }
 
+done:
   if (update)
     gst_query_set_nth_allocation_pool (query, 0, pool, size, min, max);
   else
@@ -3184,9 +3220,20 @@ gst_v4l2_object_decide_allocation (GstV4l2Object * obj, GstQuery * query)
   return TRUE;
 
 pool_failed:
+  {
+    /* setup_pool already send the error */
+    return FALSE;
+  }
+config_failed:
+  {
+    GST_ELEMENT_ERROR (obj->element, RESOURCE, SETTINGS,
+        (_("Failed to configure internal buffer pool.")), (NULL));
+    return FALSE;
+  }
+no_size:
   {
     GST_ELEMENT_ERROR (obj->element, RESOURCE, SETTINGS,
-        (_("Video device could not create buffer pool.")), GST_ERROR_SYSTEM);
+        (_("Video device did not suggest any buffer size.")), (NULL));
     return FALSE;
   }
 }