From 927cf4cfdcbe36119267fc0711e174249da857a3 Mon Sep 17 00:00:00 2001
From: deadprogram <ron@hybridgroup.com>
Date: Sun, 8 Oct 2017 12:58:25 +0200
Subject: [PATCH] Ability to select the desired VideoWriter output codec on
 Open()

Signed-off-by: deadprogram <ron@hybridgroup.com>
---
 cmd/savevideo/main.go |  2 +-
 videoio.cpp           |  5 +++--
 videoio.go            | 14 ++++++++++++--
 videoio.h             |  2 +-
 videoio_test.go       |  2 +-
 5 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/cmd/savevideo/main.go b/cmd/savevideo/main.go
index 2ccfe9f9..f08caaa6 100644
--- a/cmd/savevideo/main.go
+++ b/cmd/savevideo/main.go
@@ -45,7 +45,7 @@ func main() {
 		return
 	}
 
-	writer, err := gocv.VideoWriterFile(saveFile, 25, img.Cols(), img.Rows())
+	writer, err := gocv.VideoWriterFile(saveFile, "MJPG", 25, img.Cols(), img.Rows())
 	if err != nil {
 		fmt.Printf("error opening video writer device: %v\n", saveFile)
 		return
diff --git a/videoio.cpp b/videoio.cpp
index ebfad579..f1b1b8a6 100644
--- a/videoio.cpp
+++ b/videoio.cpp
@@ -44,9 +44,10 @@ void VideoWriter_Close(VideoWriter vw) {
     delete vw;
 }
   
-void VideoWriter_Open(VideoWriter vw, const char* name, double fps, int width,
+void VideoWriter_Open(VideoWriter vw, const char* name, const char* codec, double fps, int width,
       int height) {
-    vw->open(name, CV_FOURCC('M', 'J', 'P', 'G'), fps, cv::Size(width, height), true);
+    int codecCode = cv::VideoWriter::fourcc(codec[0], codec[1], codec[2], codec[3]);
+    vw->open(name, codecCode, fps, cv::Size(width, height), true);
 }
 
 int VideoWriter_IsOpened(VideoWriter vw) {
diff --git a/videoio.go b/videoio.go
index ba3ab783..2bca171f 100644
--- a/videoio.go
+++ b/videoio.go
@@ -219,7 +219,13 @@ type VideoWriter struct {
 }
 
 // VideoWriterFile opens a VideoWriter with a specific output file.
-func VideoWriterFile(name string, fps float64, width int, height int) (vw *VideoWriter, err error) {
+// The "codec" param should be the four-letter code for the desired output
+// codec, for example "MJPG".
+//
+// For further details, please see:
+// http://docs.opencv.org/3.3.0/dd/d9e/classcv_1_1VideoWriter.html#a0901c353cd5ea05bba455317dab81130
+//
+func VideoWriterFile(name string, codec string, fps float64, width int, height int) (vw *VideoWriter, err error) {
 	vw = &VideoWriter{
 		p:  C.VideoWriter_New(),
 		mu: &sync.RWMutex{},
@@ -227,7 +233,11 @@ func VideoWriterFile(name string, fps float64, width int, height int) (vw *Video
 
 	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))
+
+	cCodec := C.CString(codec)
+	defer C.free(unsafe.Pointer(cCodec))
+
+	C.VideoWriter_Open(vw.p, cName, cCodec, C.double(fps), C.int(width), C.int(height))
 	return
 }
 
diff --git a/videoio.h b/videoio.h
index 72e61dd0..8b5cd9f0 100644
--- a/videoio.h
+++ b/videoio.h
@@ -29,7 +29,7 @@ void VideoCapture_Grab(VideoCapture v, int skip);
 // VideoWriter
 VideoWriter VideoWriter_New();
 void VideoWriter_Close(VideoWriter vw);
-void VideoWriter_Open(VideoWriter vw, const char* name, double fps, int width,
+void VideoWriter_Open(VideoWriter vw, const char* name, const char* codec, double fps, int width,
   int height);
 int VideoWriter_IsOpened(VideoWriter vw);
 void VideoWriter_Write(VideoWriter vw, Mat img);
diff --git a/videoio_test.go b/videoio_test.go
index 9eccc30b..4f183a1b 100644
--- a/videoio_test.go
+++ b/videoio_test.go
@@ -31,7 +31,7 @@ func TestVideoWriterFile(t *testing.T) {
 	}
 	defer img.Close()
 
-	vw, _ := VideoWriterFile("/tmp/test.avi", 25, img.Cols(), img.Rows())
+	vw, _ := VideoWriterFile("/tmp/test.avi", "MJPG", 25, img.Cols(), img.Rows())
 	defer vw.Close()
 
 	if !vw.IsOpened() {