From e1f03b55a1aeb548ec544c68f4a4284f51cf4924 Mon Sep 17 00:00:00 2001
From: Milan Nikolic <gen2brain@gmail.com>
Date: Wed, 14 Mar 2018 14:33:01 +0100
Subject: [PATCH] Reuse frame

---
 camera/camera.go     |  6 ++++--
 camera/camera_cv3.go | 12 +++++++-----
 video/video.go       |  6 ++++--
 video/video_cv3.go   | 12 +++++++-----
 4 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/camera/camera.go b/camera/camera.go
index c7fae31..2804f67 100644
--- a/camera/camera.go
+++ b/camera/camera.go
@@ -13,6 +13,7 @@ import (
 // Camera represents camera.
 type Camera struct {
 	camera *opencv.Capture
+	frame  *opencv.IplImage
 }
 
 // New returns new Camera for given camera index.
@@ -30,8 +31,8 @@ func New(index int) (camera *Camera, err error) {
 // Read reads next frame from camera and returns image.
 func (c *Camera) Read() (img image.Image, err error) {
 	if c.camera.GrabFrame() {
-		frame := c.camera.RetrieveFrame(1)
-		img = frame.ToImage()
+		c.frame = c.camera.RetrieveFrame(1)
+		img = c.frame.ToImage()
 	} else {
 		err = fmt.Errorf("camera: can not grab frame")
 	}
@@ -56,6 +57,7 @@ func (c *Camera) Close() (err error) {
 		return
 	}
 
+	c.frame.Release()
 	c.camera.Release()
 	c.camera = nil
 	return
diff --git a/camera/camera_cv3.go b/camera/camera_cv3.go
index b6248ff..72fe606 100644
--- a/camera/camera_cv3.go
+++ b/camera/camera_cv3.go
@@ -13,12 +13,16 @@ import (
 // Camera represents camera.
 type Camera struct {
 	camera *gocv.VideoCapture
+	frame  *gocv.Mat
 }
 
 // New returns new Camera for given camera index.
 func New(index int) (camera *Camera, err error) {
 	camera = &Camera{}
 
+	mat := gocv.NewMat()
+	camera.frame = &mat
+
 	camera.camera, err = gocv.VideoCaptureDevice(index)
 	if err != nil {
 		err = fmt.Errorf("camera: can not open camera %d: %s", index, err.Error())
@@ -29,16 +33,13 @@ func New(index int) (camera *Camera, err error) {
 
 // Read reads next frame from camera and returns image.
 func (c *Camera) Read() (img image.Image, err error) {
-	mat := gocv.NewMat()
-	defer mat.Close()
-
-	ok := c.camera.Read(mat)
+	ok := c.camera.Read(*c.frame)
 	if !ok {
 		err = fmt.Errorf("camera: can not grab frame")
 		return
 	}
 
-	img, e := mat.ToImage()
+	img, e := c.frame.ToImage()
 	if e != nil {
 		err = fmt.Errorf("camera: %v", e)
 		return
@@ -64,6 +65,7 @@ func (c *Camera) Close() (err error) {
 		return
 	}
 
+	c.frame.Close()
 	err = c.camera.Close()
 	c.camera = nil
 	return
diff --git a/video/video.go b/video/video.go
index 1894360..5e28532 100644
--- a/video/video.go
+++ b/video/video.go
@@ -13,6 +13,7 @@ import (
 // Video represents video.
 type Video struct {
 	video *opencv.Capture
+	frame *opencv.IplImage
 }
 
 // New returns new Video for given path.
@@ -30,8 +31,8 @@ func New(filename string) (video *Video, err error) {
 // Read reads next frame from video and returns image.
 func (v *Video) Read() (img image.Image, err error) {
 	if v.video.GrabFrame() {
-		frame := v.video.RetrieveFrame(1)
-		img = frame.ToImage()
+		v.frame = v.video.RetrieveFrame(1)
+		img = v.frame.ToImage()
 	} else {
 		err = fmt.Errorf("video: can not grab frame")
 	}
@@ -46,6 +47,7 @@ func (v *Video) Close() (err error) {
 		return
 	}
 
+	v.frame.Release()
 	v.video.Release()
 	v.video = nil
 	return
diff --git a/video/video_cv3.go b/video/video_cv3.go
index f507403..dfaf77e 100644
--- a/video/video_cv3.go
+++ b/video/video_cv3.go
@@ -13,12 +13,16 @@ import (
 // Video represents video.
 type Video struct {
 	video *gocv.VideoCapture
+	frame *gocv.Mat
 }
 
 // New returns new Video for given path.
 func New(filename string) (video *Video, err error) {
 	video = &Video{}
 
+	mat := gocv.NewMat()
+	video.frame = &mat
+
 	video.video, err = gocv.VideoCaptureFile(filename)
 	if err != nil {
 		err = fmt.Errorf("video: can not open video %s: %s", filename, err.Error())
@@ -29,16 +33,13 @@ func New(filename string) (video *Video, err error) {
 
 // Read reads next frame from video and returns image.
 func (v *Video) Read() (img image.Image, err error) {
-	mat := gocv.NewMat()
-	defer mat.Close()
-
-	ok := v.video.Read(mat)
+	ok := v.video.Read(*v.frame)
 	if !ok {
 		err = fmt.Errorf("video: can not grab frame")
 		return
 	}
 
-	img, e := mat.ToImage()
+	img, e := v.frame.ToImage()
 	if e != nil {
 		err = fmt.Errorf("video: %v", e)
 		return
@@ -54,6 +55,7 @@ func (v *Video) Close() (err error) {
 		return
 	}
 
+	v.frame.Close()
 	err = v.video.Close()
 	v.video = nil
 	return