diff --git a/revid/config/variables.go b/revid/config/variables.go
index f84fa02b..29869804 100644
--- a/revid/config/variables.go
+++ b/revid/config/variables.go
@@ -37,6 +37,69 @@ import (
 	"bitbucket.org/ausocean/utils/logger"
 )
 
+// Config map keys.
+const (
+	keyAutoWhiteBalance  = "AutoWhiteBalance"
+	keyBitDepth          = "BitDepth"
+	keyBitrate           = "Bitrate"
+	keyBrightness        = "Brightness"
+	keyBurstPeriod       = "BurstPeriod"
+	keyCameraChan        = "CameraChan"
+	keyCameraIP          = "CameraIP"
+	keyCBR               = "CBR"
+	keyClipDuration      = "ClipDuration"
+	keyChannels          = "Channels"
+	keyExposure          = "Exposure"
+	keyFileFPS           = "FileFPS"
+	keyFilters           = "Filters"
+	keyFrameRate         = "FrameRate"
+	keyHeight            = "Height"
+	keyHorizontalFlip    = "HorizontalFlip"
+	keyHTTPAddress       = "HTTPAddress"
+	keyInput             = "Input"
+	keyInputCodec        = "InputCodec"
+	keyInputPath         = "InputPath"
+	keyLogging           = "logging"
+	keyLoop              = "Loop"
+	keyMinFPS            = "MinFPS"
+	keyMinFrames         = "MinFrames"
+	keyMode              = "mode"
+	keyMotionDownscaling = "MotionDownscaling"
+	keyMotionHistory     = "MotionHistory"
+	keyMotionInterval    = "MotionInterval"
+	keyMotionKernel      = "MotionKernel"
+	keyMotionMinArea     = "MotionMinArea"
+	keyMotionPadding     = "MotionPadding"
+	keyMotionPixels      = "MotionPixels"
+	keyMotionThreshold   = "MotionThreshold"
+	keyOutput            = "Output"
+	keyOutputPath        = "OutputPath"
+	keyOutputs           = "Outputs"
+	keyPSITime           = "PSITime"
+	keyQuantization      = "Quantization"
+	keyRBCapacity        = "RBCapacity"
+	keyRBWriteTimeout    = "RBWriteTimeout"
+	keyRecPeriod         = "RecPeriod"
+	keyRotation          = "Rotation"
+	keyRTMPURL           = "RTMPURL"
+	keyRTPAddress        = "RTPAddress"
+	keySampleRate        = "SampleRate"
+	keySaturation        = "Saturation"
+	keySuppress          = "Suppress"
+	keyVBRBitrate        = "VBRBitrate"
+	keyVBRQuality        = "VBRQuality"
+	keyVerticalFlip      = "VerticalFlip"
+	keyWidth             = "Width"
+)
+
+// Config map parameter types.
+const (
+	typeString = "string"
+	typeUint   = "uint"
+	typeBool   = "bool"
+	typeFloat  = "float"
+)
+
 // Default variable values.
 const (
 	// General revid defaults.
@@ -68,60 +131,60 @@ var Variables = []struct {
 	Validate func(*Config)
 }{
 	{
-		Name:   "AutoWhiteBalance",
+		Name:   keyAutoWhiteBalance,
 		Type_:  "enum:off,auto,sun,cloud,shade,tungsten,fluorescent,incandescent,flash,horizon",
 		Update: func(c *Config, v string) { c.AutoWhiteBalance = v },
 	},
 	{
-		Name:   "BitDepth",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.BitDepth = parseUint("BitDepth", v, c) },
+		Name:   keyBitDepth,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.BitDepth = parseUint(keyBitDepth, v, c) },
 	},
 	{
-		Name:   "Bitrate",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.Bitrate = parseUint("Bitrate", v, c) },
+		Name:   keyBitrate,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.Bitrate = parseUint(keyBitrate, v, c) },
 	},
 	{
-		Name:   "Brightness",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.Brightness = parseUint("Brightness", v, c) },
+		Name:   keyBrightness,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.Brightness = parseUint(keyBrightness, v, c) },
 	},
 	{
-		Name:   "BurstPeriod",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.BurstPeriod = parseUint("BurstPeriod", v, c) },
+		Name:   keyBurstPeriod,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.BurstPeriod = parseUint(keyBurstPeriod, v, c) },
 		Validate: func(c *Config) {
 			if c.BurstPeriod <= 0 {
-				c.LogInvalidField("BurstPeriod", defaultBurstPeriod)
+				c.LogInvalidField(keyBurstPeriod, defaultBurstPeriod)
 				c.BurstPeriod = defaultBurstPeriod
 			}
 		},
 	},
 	{
-		Name:   "CameraChan",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.CameraChan = uint8(parseUint("CameraChan", v, c)) },
+		Name:   keyCameraChan,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.CameraChan = uint8(parseUint(keyCameraChan, v, c)) },
 	},
 	{
-		Name:   "CameraIP",
-		Type_:  "string",
+		Name:   keyCameraIP,
+		Type_:  typeString,
 		Update: func(c *Config, v string) { c.CameraIP = v },
 		Validate: func(c *Config) {
 			if c.CameraIP == "" {
-				c.LogInvalidField("CameraIP", defaultCameraIP)
+				c.LogInvalidField(keyCameraIP, defaultCameraIP)
 				c.CameraIP = defaultCameraIP
 			}
 		},
 	},
 	{
-		Name:   "CBR",
-		Type_:  "bool",
-		Update: func(c *Config, v string) { c.CBR = parseBool("CBR", v, c) },
+		Name:   keyCBR,
+		Type_:  typeBool,
+		Update: func(c *Config, v string) { c.CBR = parseBool(keyCBR, v, c) },
 	},
 	{
-		Name:  "ClipDuration",
-		Type_: "uint",
+		Name:  keyClipDuration,
+		Type_: typeUint,
 		Update: func(c *Config, v string) {
 			_v, err := strconv.Atoi(v)
 			if err != nil {
@@ -131,34 +194,34 @@ var Variables = []struct {
 		},
 		Validate: func(c *Config) {
 			if c.ClipDuration <= 0 {
-				c.LogInvalidField("ClipDuration", defaultClipDuration)
+				c.LogInvalidField(keyClipDuration, defaultClipDuration)
 				c.ClipDuration = defaultClipDuration
 			}
 		},
 	},
 	{
-		Name:   "Channels",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.Channels = parseUint("Channels", v, c) },
+		Name:   keyChannels,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.Channels = parseUint(keyChannels, v, c) },
 	},
 	{
-		Name:   "Exposure",
+		Name:   keyExposure,
 		Type_:  "enum:auto,night,nightpreview,backlight,spotlight,sports,snow,beach,verylong,fixedfps,antishake,fireworks",
 		Update: func(c *Config, v string) { c.Exposure = v },
 	},
 	{
-		Name:   "FileFPS",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.FileFPS = parseUint("FileFPS", v, c) },
+		Name:   keyFileFPS,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.FileFPS = parseUint(keyFileFPS, v, c) },
 		Validate: func(c *Config) {
 			if c.FileFPS <= 0 || (c.FileFPS > 0 && c.Input != InputFile) {
-				c.LogInvalidField("FileFPS", defaultFileFPS)
+				c.LogInvalidField(keyFileFPS, defaultFileFPS)
 				c.FileFPS = defaultFileFPS
 			}
 		},
 	},
 	{
-		Name:  "Filters",
+		Name:  keyFilters,
 		Type_: "enums:NoOp,MOG,VariableFPS,KNN,Difference,Basic",
 		Update: func(c *Config, v string) {
 			filters := strings.Split(v, ",")
@@ -174,37 +237,37 @@ var Variables = []struct {
 		},
 	},
 	{
-		Name:   "FrameRate",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.FrameRate = parseUint("FrameRate", v, c) },
+		Name:   keyFrameRate,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.FrameRate = parseUint(keyFrameRate, v, c) },
 		Validate: func(c *Config) {
 			if c.FrameRate <= 0 || c.FrameRate > 60 {
-				c.LogInvalidField("FrameRate", defaultFrameRate)
+				c.LogInvalidField(keyFrameRate, defaultFrameRate)
 				c.FrameRate = defaultFrameRate
 			}
 		},
 	},
 	{
-		Name:   "Height",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.Height = parseUint("Height", v, c) },
+		Name:   keyHeight,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.Height = parseUint(keyHeight, v, c) },
 	},
 	{
-		Name:   "HorizontalFlip",
-		Type_:  "bool",
-		Update: func(c *Config, v string) { c.HorizontalFlip = parseBool("HorizontalFlip", v, c) },
+		Name:   keyHorizontalFlip,
+		Type_:  typeBool,
+		Update: func(c *Config, v string) { c.HorizontalFlip = parseBool(keyHorizontalFlip, v, c) },
 	},
 	{
-		Name:   "HTTPAddress",
-		Type_:  "string",
+		Name:   keyHTTPAddress,
+		Type_:  typeString,
 		Update: func(c *Config, v string) { c.HTTPAddress = v },
 	},
 	{
-		Name:  "Input",
+		Name:  keyInput,
 		Type_: "enum:raspivid,rtsp,v4l,file,audio",
 		Update: func(c *Config, v string) {
 			c.Input = parseEnum(
-				"Input",
+				keyInput,
 				v,
 				map[string]uint8{
 					"raspivid": InputRaspivid,
@@ -220,17 +283,17 @@ var Variables = []struct {
 			switch c.Input {
 			case InputRaspivid, InputV4L, InputFile, InputAudio, InputRTSP:
 			default:
-				c.LogInvalidField("Input", defaultInput)
+				c.LogInvalidField(keyInput, defaultInput)
 				c.Input = defaultInput
 			}
 		},
 	},
 	{
-		Name:  "InputCodec",
+		Name:  keyInputCodec,
 		Type_: "enum:H264,H265,MJPEG,PCM,ADPCM",
 		Update: func(c *Config, v string) {
 			c.InputCodec = parseEnum(
-				"InputCodec",
+				keyInputCodec,
 				v,
 				map[string]uint8{
 					"h264":  codecutil.H264,
@@ -246,18 +309,18 @@ var Variables = []struct {
 			switch c.InputCodec {
 			case codecutil.H264, codecutil.MJPEG, codecutil.PCM, codecutil.ADPCM:
 			default:
-				c.LogInvalidField("InputCodec", defaultInputCodec)
+				c.LogInvalidField(keyInputCodec, defaultInputCodec)
 				c.InputCodec = defaultInputCodec
 			}
 		},
 	},
 	{
-		Name:   "InputPath",
-		Type_:  "string",
+		Name:   keyInputPath,
+		Type_:  typeString,
 		Update: func(c *Config, v string) { c.InputPath = v },
 	},
 	{
-		Name:  "logging",
+		Name:  keyLogging,
 		Type_: "enum:Debug,Info,Warning,Error,Fatal",
 		Update: func(c *Config, v string) {
 			switch v {
@@ -285,61 +348,61 @@ var Variables = []struct {
 		},
 	},
 	{
-		Name:   "Loop",
-		Type_:  "bool",
-		Update: func(c *Config, v string) { c.Loop = parseBool("Loop", v, c) },
+		Name:   keyLoop,
+		Type_:  typeBool,
+		Update: func(c *Config, v string) { c.Loop = parseBool(keyLoop, v, c) },
 	},
 	{
-		Name:     "MinFPS",
-		Type_:    "uint",
-		Update:   func(c *Config, v string) { c.MinFPS = parseUint("MinFPS", v, c) },
-		Validate: func(c *Config) { c.MinFPS = lessThanOrEqual("MinFPS", c.MinFPS, 0, c, defaultMinFPS) },
+		Name:     keyMinFPS,
+		Type_:    typeUint,
+		Update:   func(c *Config, v string) { c.MinFPS = parseUint(keyMinFPS, v, c) },
+		Validate: func(c *Config) { c.MinFPS = lessThanOrEqual(keyMinFPS, c.MinFPS, 0, c, defaultMinFPS) },
 	},
 	{
-		Name:   "MinFrames",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.MinFrames = parseUint("MinFrames", v, c) },
+		Name:   keyMinFrames,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.MinFrames = parseUint(keyMinFrames, v, c) },
 		Validate: func(c *Config) {
 			const maxMinFrames = 1000
 			if c.MinFrames <= 0 || c.MinFrames > maxMinFrames {
-				c.LogInvalidField("MinFrames", defaultMinFrames)
+				c.LogInvalidField(keyMinFrames, defaultMinFrames)
 				c.MinFrames = defaultMinFrames
 			}
 		},
 	},
 	{
-		Name:  "mode",
+		Name:  keyMode,
 		Type_: "enum:Normal,Paused,Burst,Loop",
 		Update: func(c *Config, v string) {
 			c.Loop = false
-			if v == "Loop" {
+			if v == keyLoop {
 				c.Loop = true
 			}
 		},
 	},
 	{
-		Name:   "MotionDownscaling",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.MotionDownscaling = parseUint("MotionDownscaling", v, c) },
+		Name:   keyMotionDownscaling,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.MotionDownscaling = parseUint(keyMotionDownscaling, v, c) },
 	},
 	{
-		Name:   "MotionHistory",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.MotionHistory = parseUint("MotionHistory", v, c) },
+		Name:   keyMotionHistory,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.MotionHistory = parseUint(keyMotionHistory, v, c) },
 	},
 	{
-		Name:   "MotionInterval",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.MotionInterval = parseUint("MotionInterval", v, c) },
+		Name:   keyMotionInterval,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.MotionInterval = parseUint(keyMotionInterval, v, c) },
 	},
 	{
-		Name:   "MotionKernel",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.MotionKernel = parseUint("MotionKernel", v, c) },
+		Name:   keyMotionKernel,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.MotionKernel = parseUint(keyMotionKernel, v, c) },
 	},
 	{
-		Name:  "MotionMinArea",
-		Type_: "float",
+		Name:  keyMotionMinArea,
+		Type_: typeFloat,
 		Update: func(c *Config, v string) {
 			f, err := strconv.ParseFloat(v, 64)
 			if err != nil {
@@ -349,18 +412,18 @@ var Variables = []struct {
 		},
 	},
 	{
-		Name:   "MotionPadding",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.MotionPadding = parseUint("MotionPadding", v, c) },
+		Name:   keyMotionPadding,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.MotionPadding = parseUint(keyMotionPadding, v, c) },
 	},
 	{
-		Name:   "MotionPixels",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.MotionPixels = parseUint("MotionPixels", v, c) },
+		Name:   keyMotionPixels,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.MotionPixels = parseUint(keyMotionPixels, v, c) },
 	},
 	{
-		Name:  "MotionThreshold",
-		Type_: "float",
+		Name:  keyMotionThreshold,
+		Type_: typeFloat,
 		Update: func(c *Config, v string) {
 			f, err := strconv.ParseFloat(v, 64)
 			if err != nil {
@@ -370,7 +433,7 @@ var Variables = []struct {
 		},
 	},
 	{
-		Name:  "Output",
+		Name:  keyOutput,
 		Type_: "enum:File,HTTP,RTMP,RTP",
 		Update: func(c *Config, v string) {
 			c.Outputs = make([]uint8, 1)
@@ -389,12 +452,12 @@ var Variables = []struct {
 		},
 	},
 	{
-		Name:   "OutputPath",
-		Type_:  "string",
+		Name:   keyOutputPath,
+		Type_:  typeString,
 		Update: func(c *Config, v string) { c.OutputPath = v },
 	},
 	{
-		Name:  "Outputs",
+		Name:  keyOutputs,
 		Type_: "enums:File,HTTP,RTMP,RTP",
 		Update: func(c *Config, v string) {
 			outputs := strings.Split(v, ",")
@@ -416,75 +479,75 @@ var Variables = []struct {
 		},
 		Validate: func(c *Config) {
 			if c.Outputs == nil {
-				c.LogInvalidField("Outputs", defaultOutput)
+				c.LogInvalidField(keyOutputs, defaultOutput)
 				c.Outputs = append(c.Outputs, defaultOutput)
 			}
 		},
 	},
 	{
-		Name:     "PSITime",
-		Type_:    "uint",
-		Update:   func(c *Config, v string) { c.PSITime = parseUint("PSITime", v, c) },
-		Validate: func(c *Config) { c.PSITime = lessThanOrEqual("PSITime", c.PSITime, 0, c, defaultPSITime) },
+		Name:     keyPSITime,
+		Type_:    typeUint,
+		Update:   func(c *Config, v string) { c.PSITime = parseUint(keyPSITime, v, c) },
+		Validate: func(c *Config) { c.PSITime = lessThanOrEqual(keyPSITime, c.PSITime, 0, c, defaultPSITime) },
 	},
 	{
-		Name:   "Quantization",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.Quantization = parseUint("Quantization", v, c) },
+		Name:   keyQuantization,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.Quantization = parseUint(keyQuantization, v, c) },
 	},
 	{
-		Name:     "RBCapacity",
-		Type_:    "uint",
-		Update:   func(c *Config, v string) { c.RBCapacity = parseUint("RBCapacity", v, c) },
-		Validate: func(c *Config) { c.RBCapacity = lessThanOrEqual("RBCapacity", c.RBCapacity, 0, c, defaultRBCapacity) },
+		Name:     keyRBCapacity,
+		Type_:    typeUint,
+		Update:   func(c *Config, v string) { c.RBCapacity = parseUint(keyRBCapacity, v, c) },
+		Validate: func(c *Config) { c.RBCapacity = lessThanOrEqual(keyRBCapacity, c.RBCapacity, 0, c, defaultRBCapacity) },
 	},
 	{
-		Name:   "RBWriteTimeout",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.RBWriteTimeout = parseUint("RBWriteTimeout", v, c) },
+		Name:   keyRBWriteTimeout,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.RBWriteTimeout = parseUint(keyRBWriteTimeout, v, c) },
 		Validate: func(c *Config) {
-			c.RBWriteTimeout = lessThanOrEqual("RBWriteTimeout", c.RBWriteTimeout, 0, c, defaultRBWriteTimeout)
+			c.RBWriteTimeout = lessThanOrEqual(keyRBWriteTimeout, c.RBWriteTimeout, 0, c, defaultRBWriteTimeout)
 		},
 	},
 	{
-		Name:  "RecPeriod",
-		Type_: "float",
+		Name:  keyRecPeriod,
+		Type_: typeFloat,
 		Update: func(c *Config, v string) {
 			_v, err := strconv.ParseFloat(v, 64)
 			if err != nil {
-				c.Logger.Log(logger.Warning, fmt.Sprintf("invalid %s param", "RecPeriod"), "value", v)
+				c.Logger.Log(logger.Warning, fmt.Sprintf("invalid %s param", keyRecPeriod), "value", v)
 			}
 			c.RecPeriod = _v
 		},
 	},
 	{
-		Name:   "Rotation",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.Rotation = parseUint("Rotation", v, c) },
+		Name:   keyRotation,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.Rotation = parseUint(keyRotation, v, c) },
 	},
 	{
-		Name:   "RTMPURL",
-		Type_:  "string",
+		Name:   keyRTMPURL,
+		Type_:  typeString,
 		Update: func(c *Config, v string) { c.RTMPURL = v },
 	},
 	{
-		Name:   "RTPAddress",
-		Type_:  "string",
+		Name:   keyRTPAddress,
+		Type_:  typeString,
 		Update: func(c *Config, v string) { c.RTPAddress = v },
 		Validate: func(c *Config) {
 			if c.RTPAddress == "" {
-				c.LogInvalidField("RTPAddress", defaultRTPAddr)
+				c.LogInvalidField(keyRTPAddress, defaultRTPAddr)
 				c.RTPAddress = defaultRTPAddr
 			}
 		},
 	},
 	{
-		Name:   "SampleRate",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.SampleRate = parseUint("SampleRate", v, c) },
+		Name:   keySampleRate,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.SampleRate = parseUint(keySampleRate, v, c) },
 	},
 	{
-		Name:  "Saturation",
+		Name:  keySaturation,
 		Type_: "int",
 		Update: func(c *Config, v string) {
 			_v, err := strconv.Atoi(v)
@@ -495,24 +558,24 @@ var Variables = []struct {
 		},
 	},
 	{
-		Name:  "Suppress",
-		Type_: "bool",
+		Name:  keySuppress,
+		Type_: typeBool,
 		Update: func(c *Config, v string) {
-			c.Suppress = parseBool("Suppress", v, c)
+			c.Suppress = parseBool(keySuppress, v, c)
 			c.Logger.(*logger.Logger).SetSuppress(c.Suppress)
 		},
 	},
 	{
-		Name:   "VBRBitrate",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.VBRBitrate = parseUint("VBRBitrate", v, c) },
+		Name:   keyVBRBitrate,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.VBRBitrate = parseUint(keyVBRBitrate, v, c) },
 	},
 	{
-		Name:  "VBRQuality",
+		Name:  keyVBRQuality,
 		Type_: "enum:standard,fair,good,great,excellent",
 		Update: func(c *Config, v string) {
 			c.VBRQuality = Quality(parseEnum(
-				"VBRQuality",
+				keyVBRQuality,
 				v,
 				map[string]uint8{
 					"standard":  uint8(QualityStandard),
@@ -526,14 +589,14 @@ var Variables = []struct {
 		},
 	},
 	{
-		Name:   "VerticalFlip",
-		Type_:  "bool",
-		Update: func(c *Config, v string) { c.VerticalFlip = parseBool("VerticalFlip", v, c) },
+		Name:   keyVerticalFlip,
+		Type_:  typeBool,
+		Update: func(c *Config, v string) { c.VerticalFlip = parseBool(keyVerticalFlip, v, c) },
 	},
 	{
-		Name:   "Width",
-		Type_:  "uint",
-		Update: func(c *Config, v string) { c.Width = parseUint("Width", v, c) },
+		Name:   keyWidth,
+		Type_:  typeUint,
+		Update: func(c *Config, v string) { c.Width = parseUint(keyWidth, v, c) },
 	},
 }