v4l2transform: Setup cropping if needed

sys/v4l2/gstv4l2object.c

@@ -2825,6 +2825,39 @@ unsupported_format:
   }
 }
 
+gboolean
+gst_v4l2_object_set_crop (GstV4l2Object * obj)
+{
+  struct v4l2_crop crop = { 0 };
+
+  crop.type = obj->type;
+  crop.c.left = obj->align.padding_left;
+  crop.c.top = obj->align.padding_top;
+  crop.c.width = obj->info.width;
+  crop.c.height = obj->info.height;
+
+  if (obj->align.padding_left + obj->align.padding_top +
+      obj->align.padding_right + obj->align.padding_bottom == 0) {
+    GST_DEBUG_OBJECT (obj->element, "no cropping needed");
+    return TRUE;
+  }
+
+  GST_DEBUG_OBJECT (obj->element,
+      "Desired cropping left %u, top %u, size %ux%u", crop.c.left, crop.c.top,
+      crop.c.width, crop.c.height);
+
+  if (v4l2_ioctl (obj->video_fd, VIDIOC_S_CROP, &crop) < 0) {
+    GST_WARNING_OBJECT (obj->element, "VIDIOC_S_CROP failed");
+    return FALSE;
+  }
+
+  GST_DEBUG_OBJECT (obj->element,
+      "Got cropping left %u, top %u, size %ux%u", crop.c.left, crop.c.top,
+      crop.c.width, crop.c.height);
+
+  return TRUE;
+}
+
 gboolean
 gst_v4l2_object_caps_equal (GstV4l2Object * v4l2object, GstCaps * caps)
 {

sys/v4l2/gstv4l2object.h

@@ -262,6 +262,8 @@ GstCaps *     gst_v4l2_object_get_caps    (GstV4l2Object * v4l2object,
 
 gboolean      gst_v4l2_object_acquire_format (GstV4l2Object * v4l2object,
                                               GstVideoInfo * info);
+
+gboolean      gst_v4l2_object_set_crop    (GstV4l2Object * obj);
  
 gboolean      gst_v4l2_object_decide_allocation (GstV4l2Object * v4l2object,
                                                  GstQuery * query);

sys/v4l2/gstv4l2transform.c

@@ -209,23 +209,30 @@ gst_v4l2_transform_set_caps (GstBaseTransform * trans, GstCaps * incaps,
   if (!gst_v4l2_object_set_format (self->v4l2capture, outcaps))
     goto outcaps_failed;
 
-  return TRUE;
+  /* FIXME implement fallback if crop not supported */
+  if (!gst_v4l2_object_set_crop (self->v4l2output))
+    goto failed;
 
+  if (!gst_v4l2_object_set_crop (self->v4l2capture))
+    goto failed;
+
+  return TRUE;
 
 incaps_failed:
   {
     GST_ERROR_OBJECT (self, "failed to set input caps: %" GST_PTR_FORMAT,
         incaps);
-    return FALSE;
+    goto failed;
   }
-
 outcaps_failed:
   {
     gst_v4l2_object_stop (self->v4l2output);
     GST_ERROR_OBJECT (self, "failed to set output caps: %" GST_PTR_FORMAT,
         outcaps);
-    return FALSE;
+    goto failed;
   }
+failed:
+  return FALSE;
 }
 
 static gboolean