From 669e72e86dff35fea8669f4adc5a8a9dc3fd7c17 Mon Sep 17 00:00:00 2001
From: Scott <scott@ausocean.org>
Date: Thu, 19 Dec 2019 15:06:32 +1030
Subject: [PATCH] PR fixes

---
 filter/{filter.go => mog.go} | 45 +++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 21 deletions(-)
 rename filter/{filter.go => mog.go} (67%)

diff --git a/filter/filter.go b/filter/mog.go
similarity index 67%
rename from filter/filter.go
rename to filter/mog.go
index ed4f0d01..be0f20fb 100644
--- a/filter/filter.go
+++ b/filter/mog.go
@@ -1,13 +1,14 @@
 /*
-NAME
-  filter.go
+DESCRIPTION
+  A filter that detects motion and discards frames without motion. The
+  filter uses a Mixture of Gaussians method (MoG) to determine what is
+  background and what is foreground.
 
 AUTHORS
-  Ella Pietraroia <ella@ausocean.org>
   Scott Barnard <scott@ausocean.org>
 
 LICENSE
-  filter.go is Copyright (C) 2019 the Australian Ocean Lab (AusOcean)
+  mog.go is Copyright (C) 2019 the Australian Ocean Lab (AusOcean)
 
   It is free software: you can redistribute it and/or modify them
   under the terms of the GNU General Public License as published by the
@@ -23,7 +24,6 @@ LICENSE
   in gpl.txt.  If not, see http://www.gnu.org/licenses.
 */
 
-// Package filter provides filters that modify video streams.
 package filter
 
 import (
@@ -34,31 +34,33 @@ import (
 	"gocv.io/x/gocv"
 )
 
-// MogFilter is a filter that provides basic motion detection.
-type MogFilter struct {
+// MOGFilter is a filter that provides basic motion detection. MoG is short for
+// Mixture of Gaussians method.
+type MOGFilter struct {
 	dst     io.WriteCloser
-	minArea float64
-	mog2    *gocv.BackgroundSubtractorMOG2
-	kernel  gocv.Mat
+	area    float64
+	bs      *gocv.BackgroundSubtractorMOG2
+	knl     gocv.Mat
 	debug   bool
 	windows []*gocv.Window
 }
 
-// NewMogFilter returns a pointer to a new MogFilter
-func NewMogFilter(dst io.WriteCloser, minArea, threshold float64, history, kernelSize int, debug bool) *MogFilter {
-	mog2 := gocv.NewBackgroundSubtractorMOG2WithParams(history, threshold, false)
-	kernel := gocv.GetStructuringElement(gocv.MorphRect, image.Pt(kernelSize, kernelSize))
+// NewMOGFilter returns a pointer to a new MOGFilter.
+func NewMOGFilter(dst io.WriteCloser, area, threshold float64, history, kernelSize int, debug bool) *MogFilter {
+	bs := gocv.NewBackgroundSubtractorMOG2WithParams(history, threshold, false)
+	k := gocv.GetStructuringElement(gocv.MorphRect, image.Pt(kernelSize, kernelSize))
 	var windows []*gocv.Window
 	if debug {
-		windows = append(windows, gocv.NewWindow("Debug: Bounding boxes"), gocv.NewWindow("Debug: Motion"))
+		windows = []*gocv.Window{gocv.NewWindow("Debug: Bounding boxes"), gocv.NewWindow("Debug: Motion")}
 	}
-	return &MogFilter{dst, minArea, &mog2, kernel, debug, windows}
+	return &MOGFilter{dst, area, &bs, k, debug, windows}
 }
 
+// Implements io.Closer.
 // Close frees resources used by gocv, because it has to be done manually, due to
 // it using c-go.
-func (m *MogFilter) Close() error {
-	m.mog2.Close()
+func (m *MOGFilter) Close() error {
+	m.bs.Close()
 	m.kernel.Close()
 	for _, window := range m.windows {
 		window.Close()
@@ -66,9 +68,10 @@ func (m *MogFilter) Close() error {
 	return m.dst.Close()
 }
 
+// Implements io.Writer.
 // Write applies the motion filter to the video stream. Only frames with motion
 // are written to the destination encoder, frames without are discarded.
-func (m *MogFilter) Write(f []byte) (int, error) {
+func (m *MOGFilter) Write(f []byte) (int, error) {
 	img, _ := gocv.IMDecode(f, gocv.IMReadColor)
 	defer img.Close()
 
@@ -76,7 +79,7 @@ func (m *MogFilter) Write(f []byte) (int, error) {
 	defer imgDelta.Close()
 
 	// Seperate foreground and background.
-	m.mog2.Apply(img, &imgDelta)
+	m.bs.Apply(img, &imgDelta)
 
 	// Threshold imgDelta.
 	gocv.Threshold(imgDelta, &imgDelta, 25, 255, gocv.ThresholdBinary)
@@ -93,7 +96,7 @@ func (m *MogFilter) Write(f []byte) (int, error) {
 	var contours [][]image.Point
 	allContours := gocv.FindContours(imgDelta, gocv.RetrievalExternal, gocv.ChainApproxSimple)
 	for _, c := range allContours {
-		if gocv.ContourArea(c) > m.minArea {
+		if gocv.ContourArea(c) > m.area {
 			contours = append(contours, c)
 		}
 	}