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From 78f532d7cc31fc7e2980998af97b1260c45ec5e5 Mon Sep 17 00:00:00 2001
From: Kazunori Kobayashi <kkobayas@igel.co.jp>
Date: Thu, 10 May 2012 14:55:22 +0900
Subject: [PATCH 08/31] videocrop: kick off the zero-copy cropping
This patch enables zero-copy buffer cropping by creating a subbuffer
from an input buffer.
Instead of creating a new buffer, the subbuffer is specified as an
offset into the input buffer along with an appropriate buffer size.
The cropping functionality of gst_video_crop_transform() (which uses memory
copying) is bypassed when a subbuffer is defined.
---
gst/videocrop/gstvideocrop.c | 48 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/gst/videocrop/gstvideocrop.c b/gst/videocrop/gstvideocrop.c
index ae7ddaf..cfd548e 100644
--- a/gst/videocrop/gstvideocrop.c
+++ b/gst/videocrop/gstvideocrop.c
@@ -137,6 +137,8 @@ static gboolean gst_video_crop_set_caps (GstBaseTransform * trans,
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 void
gst_video_crop_base_init (gpointer g_class)
@@ -230,6 +232,8 @@ gst_video_crop_class_init (GstVideoCropClass * klass)
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);
basetransform_class->passthrough_on_same_caps = FALSE;
basetransform_class->src_event = GST_DEBUG_FUNCPTR (gst_video_crop_src_event);
@@ -484,6 +488,13 @@ gst_video_crop_transform (GstBaseTransform * trans, GstBuffer * inbuf,
{
GstVideoCrop *vcrop = GST_VIDEO_CROP (trans);
+ if (vcrop->stride_supported &&
+ ((vcrop->in.packing == VIDEO_CROP_PIXEL_FORMAT_PACKED_SIMPLE) ||
+ (vcrop->in.packing == VIDEO_CROP_PIXEL_FORMAT_PACKED_COMPLEX))) {
+ GST_LOG_OBJECT (vcrop, "passthrough because of zero-copy cropping");
+ return GST_FLOW_OK;
+ }
+
switch (vcrop->in.packing) {
case VIDEO_CROP_PIXEL_FORMAT_PACKED_SIMPLE:
gst_video_crop_transform_packed_simple (vcrop, inbuf, outbuf);
@@ -711,6 +722,43 @@ gst_video_crop_start (GstBaseTransform * trans)
return TRUE;
}
+static GstFlowReturn
+gst_video_crop_prepare_output_buffer (GstBaseTransform * trans,
+ GstBuffer * input, gint size, GstCaps * caps, GstBuffer ** buf)
+{
+ GstVideoCrop *vcrop = GST_VIDEO_CROP (trans);
+ guint sub_offset, sub_size;
+
+ if (!vcrop->stride_supported) {
+ GST_LOG_OBJECT
+ (vcrop,
+ "creating subbuffer isn't needed because downstream plugins don't support rowstride");
+ return GST_FLOW_OK;
+ }
+
+ if (vcrop->in.packing == VIDEO_CROP_PIXEL_FORMAT_PACKED_SIMPLE) {
+ sub_offset = (vcrop->crop_top * vcrop->in.stride) +
+ (vcrop->crop_left * vcrop->in.bytes_per_pixel);
+ } else if (vcrop->in.packing == VIDEO_CROP_PIXEL_FORMAT_PACKED_COMPLEX) {
+ sub_offset = (vcrop->crop_top * vcrop->in.stride) +
+ (ROUND_DOWN_2 (vcrop->crop_left) * vcrop->in.bytes_per_pixel);
+ } else {
+ GST_LOG_OBJECT (vcrop,
+ "can't do zero-copy cropping except for packed format");
+ return GST_FLOW_OK;
+ }
+
+ sub_size = vcrop->out.height * vcrop->out.stride;
+ *buf = gst_buffer_create_sub (input, sub_offset, sub_size);
+ if (*buf == NULL) {
+ GST_ERROR_OBJECT (vcrop, "failed to create subbuffer");
+ return GST_FLOW_ERROR;
+ }
+ gst_buffer_set_caps (*buf, caps);
+
+ return GST_FLOW_OK;
+}
+
static void
gst_video_crop_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
--
1.7.9.5
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