VideoWriter example and code working as expected, tested with MP4 and…

… AVI files

Signed-off-by: deadprogram <[email protected]>

examples/saveimage.go

@@ -1,10 +1,12 @@
 // What it does:
 //
 // This example uses the VideoCapture class to capture a frame from a connected webcam,
-// then save it to a file on disk
+// then save it to an image file on disk
 //
 // How to run:
 //
+// saveimage [camera ID] [image file]
+//
 // 		go run ./examples/saveimage.go filename.jpg
 //
 // +build example
@@ -14,16 +16,24 @@ package main
 import (
 	"fmt"
 	"os"
+	"strconv"
 
 	opencv3 ".."
 )
 
 func main() {
-	deviceID := 0
+	if len(os.Args) < 3 {
+		fmt.Println("How to run:\n\tsaveimage [camera ID] [image file]")
+		return
+	}
+
+	deviceID, _ := strconv.Atoi(os.Args[1])
+	saveFile := os.Args[2]
+
 	webcam := opencv3.NewVideoCapture()
 	defer webcam.Delete()
 
-	if ok := webcam.OpenDevice(int(deviceID)); !ok {
+	if ok := webcam.OpenDevice(deviceID); !ok {
 		fmt.Printf("error opening device: %v\n", deviceID)
 	}
 
@@ -39,5 +49,5 @@ func main() {
 		return
 	}
 
-	opencv3.IMWrite(os.Args[1], img)
+	opencv3.IMWrite(saveFile, img)
 }

examples/savevideo.go

@@ -0,0 +1,64 @@
+// What it does:
+//
+// This example uses the VideoCapture class to capture video from a connected webcam,
+// and save it to a video file on disk
+//
+// How to run:
+//
+// savevideo [camera ID] [video file]
+//
+// 		go run ./examples/savevideo.go 0 testvideo.mp4
+//
+// +build example
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+
+	opencv3 ".."
+)
+
+func main() {
+	if len(os.Args) < 3 {
+		fmt.Println("How to run:\n\tsavevideo [camera ID] [video file]")
+		return
+	}
+
+	deviceID, _ := strconv.Atoi(os.Args[1])
+	saveFile := os.Args[2]
+
+	webcam := opencv3.NewVideoCapture()
+	defer webcam.Delete()
+
+	writer := opencv3.NewVideoWriter()
+	defer writer.Delete()
+
+	if ok := webcam.OpenDevice(deviceID); !ok {
+		fmt.Printf("error opening device: %v\n", deviceID)
+	}
+
+	img := opencv3.NewMat()
+	defer img.Delete()
+
+	if ok := webcam.Read(img); !ok {
+		fmt.Printf("cannot read device %d\n", deviceID)
+		return
+	}
+
+	writer.OpenWithMat(saveFile, 25, img)
+
+	for i := 0; i < 100; i++ {
+		if ok := webcam.Read(img); !ok {
+			fmt.Printf("cannot read device %d\n", deviceID)
+			return
+		}
+		if img.Empty() {
+			continue
+		}
+
+		writer.Write(img)
+	}
+}

videoio.cpp

@@ -54,14 +54,14 @@ void VideoWriter_Open(VideoWriter vw, const char* name, double fps, int width,
 }
 
 void VideoWriter_OpenWithMat(VideoWriter vw, const char* name, double fps,
-      MatVec3b img) {
+      Mat img) {
     vw->open(name, CV_FOURCC('M', 'J', 'P', 'G'), fps, img->size(), true);
 }
 
 int VideoWriter_IsOpened(VideoWriter vw) {
     return vw->isOpened();
 }
 
-void VideoWriter_Write(VideoWriter vw, MatVec3b img) {
+void VideoWriter_Write(VideoWriter vw, Mat img) {
     *vw << *img;
 }

videoio.go

@@ -82,28 +82,29 @@ func (vw *VideoWriter) Delete() {
 	vw.p = nil
 }
 
-// Open a video writer.
+// Open a VideoWriter with a specific output file.
 func (vw *VideoWriter) Open(name string, fps float64, width int, height int) {
 	cName := C.CString(name)
 	defer C.free(unsafe.Pointer(cName))
 	C.VideoWriter_Open(vw.p, cName, C.double(fps), C.int(width), C.int(height))
 }
 
-// OpenWithMat opens video writer.
-func (vw *VideoWriter) OpenWithMat(name string, fps float64, img MatVec3b) {
+// OpenWithMat opens a VideoWriter with a specific output file
+// using the dimensions from a specific Mat.
+func (vw *VideoWriter) OpenWithMat(name string, fps float64, img Mat) {
 	cName := C.CString(name)
 	defer C.free(unsafe.Pointer(cName))
 	C.VideoWriter_OpenWithMat(vw.p, cName, C.double(fps), img.p)
 }
 
-// IsOpened returns the video writer opens a file or not.
+// IsOpened checks if the VideoWriter is open and ready to be written to.
 func (vw *VideoWriter) IsOpened() bool {
 	isOpend := C.VideoWriter_IsOpened(vw.p)
 	return isOpend != 0
 }
 
-// Write the image to file.
-func (vw *VideoWriter) Write(img MatVec3b) {
+// Write a single Mat image to the open VideoWriter.
+func (vw *VideoWriter) Write(img Mat) {
 	vw.mu.Lock()
 	defer vw.mu.Unlock()
 	C.VideoWriter_Write(vw.p, img.p)

videoio.h

@@ -33,9 +33,9 @@ void VideoWriter_Delete(VideoWriter vw);
 void VideoWriter_Open(VideoWriter vw, const char* name, double fps, int width,
   int height);
 void VideoWriter_OpenWithMat(VideoWriter vw, const char* name, double fps,
-  MatVec3b img);
+  Mat img);
 int VideoWriter_IsOpened(VideoWriter vw);
-void VideoWriter_Write(VideoWriter vw, MatVec3b img);
+void VideoWriter_Write(VideoWriter vw, Mat img);
 
 #ifdef __cplusplus
 }