From 554ffc759f9a87c4eac81fab91a2ac29e296c33c Mon Sep 17 00:00:00 2001
From: Kazunori Kobayashi <kkobayas@igel.co.jp>
Date: Thu, 4 Oct 2012 17:22:01 +0900
Subject: [PATCH 19/31] videocrop: send a query by the first invorker of
 query_stride_supported

The query_stride_supported() might be failed because start() method
can be called before the pipeline is constructed. To resolve this issue,
this patch has the first invoker of query_stride_supported() send
the query to downstream plugins. The result of query is cached
at the first invoking.
---
 gst/videocrop/gstvideocrop.c |   30 +++++++++++++-----------------
 gst/videocrop/gstvideocrop.h |    1 -
 2 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/gst/videocrop/gstvideocrop.c b/gst/videocrop/gstvideocrop.c
index 6b1da8a..da30c1b 100644
--- a/gst/videocrop/gstvideocrop.c
+++ b/gst/videocrop/gstvideocrop.c
@@ -137,9 +137,9 @@ static gboolean gst_video_crop_set_caps (GstBaseTransform * trans,
     GstCaps * in_caps, GstCaps * outcaps);
 static gboolean gst_video_crop_src_event (GstBaseTransform * trans,
     GstEvent * event);
-static gboolean gst_video_crop_start (GstBaseTransform * trans);
 static GstFlowReturn gst_video_crop_prepare_output_buffer (GstBaseTransform *
     trans, GstBuffer * input, gint size, GstCaps * caps, GstBuffer ** buf);
+static gboolean gst_video_crop_query_stride_supported (GstVideoCrop * vcrop);
 
 static void
 gst_video_crop_base_init (gpointer g_class)
@@ -232,7 +232,6 @@ gst_video_crop_class_init (GstVideoCropClass * klass)
   basetransform_class->set_caps = GST_DEBUG_FUNCPTR (gst_video_crop_set_caps);
   basetransform_class->get_unit_size =
       GST_DEBUG_FUNCPTR (gst_video_crop_get_unit_size);
-  basetransform_class->start = GST_DEBUG_FUNCPTR (gst_video_crop_start);
   basetransform_class->prepare_output_buffer =
       GST_DEBUG_FUNCPTR (gst_video_crop_prepare_output_buffer);
 
@@ -520,7 +519,7 @@ gst_video_crop_transform (GstBaseTransform * trans, GstBuffer * inbuf,
 {
   GstVideoCrop *vcrop = GST_VIDEO_CROP (trans);
 
-  if (vcrop->stride_supported &&
+  if (gst_video_crop_query_stride_supported (vcrop) &&
       ((vcrop->in.packing == VIDEO_CROP_PIXEL_FORMAT_PACKED_SIMPLE) ||
           (vcrop->in.packing == VIDEO_CROP_PIXEL_FORMAT_PACKED_COMPLEX) ||
           (vcrop->in.packing == VIDEO_CROP_PIXEL_FORMAT_SEMI_PLANAR))) {
@@ -688,11 +687,12 @@ gst_video_crop_transform_caps (GstBaseTransform * trans,
       delta_chroma_offs = 0;
     }
 
-    if (vcrop->stride_supported && (direction == GST_PAD_SINK) && rowstride)
+    if (gst_video_crop_query_stride_supported (vcrop) &&
+        (direction == GST_PAD_SINK) && rowstride)
       gst_structure_set (new_structure, "rowstride", G_TYPE_INT,
           (gint) rowstride, NULL);
 
-    if (vcrop->stride_supported &&
+    if (gst_video_crop_query_stride_supported (vcrop) &&
         gst_structure_get_int (structure, "chroma_byte_offset",
             &chroma_byte_offset) && delta_chroma_offs) {
       /* Adjust chroma_byte_offset because it would exceed the proper value
@@ -772,10 +772,14 @@ cropping_too_much:
 static gboolean
 gst_video_crop_query_stride_supported (GstVideoCrop * vcrop)
 {
-  gboolean result = FALSE;
+  static gboolean result = FALSE;
   GstPad *peer = gst_pad_get_peer (GST_BASE_TRANSFORM (vcrop)->srcpad);
   GstStructure *structure;
   GstQuery *query;
+  static gboolean is_query_done = FALSE;
+
+  if (is_query_done)
+    return result;
 
   structure = gst_structure_empty_new ("GstQueryStrideSupported");
   gst_structure_set (structure, "stride-supported", G_TYPE_BOOLEAN, FALSE,
@@ -788,17 +792,9 @@ gst_video_crop_query_stride_supported (GstVideoCrop * vcrop)
   gst_query_unref (query);
   gst_object_unref (peer);
 
-  return result;
-}
-
-static gboolean
-gst_video_crop_start (GstBaseTransform * trans)
-{
-  GstVideoCrop *vcrop = GST_VIDEO_CROP (trans);
-
-  vcrop->stride_supported = gst_video_crop_query_stride_supported (vcrop);
+  is_query_done = TRUE;
 
-  return TRUE;
+  return result;
 }
 
 static GstFlowReturn
@@ -808,7 +804,7 @@ gst_video_crop_prepare_output_buffer (GstBaseTransform * trans,
   GstVideoCrop *vcrop = GST_VIDEO_CROP (trans);
   guint sub_offset, sub_size;
 
-  if (!vcrop->stride_supported) {
+  if (!gst_video_crop_query_stride_supported (vcrop)) {
     GST_LOG_OBJECT
         (vcrop,
         "creating subbuffer isn't needed because downstream plugins don't support rowstride");
diff --git a/gst/videocrop/gstvideocrop.h b/gst/videocrop/gstvideocrop.h
index 2e5d5e6..1534b3d 100644
--- a/gst/videocrop/gstvideocrop.h
+++ b/gst/videocrop/gstvideocrop.h
@@ -83,7 +83,6 @@ struct _GstVideoCrop
 
   /* query for rowstride */
   GstQueryType query_type_stride;
-  gboolean stride_supported;
 };
 
 struct _GstVideoCropClass
-- 
1.7.9.5