diff --git a/cmd/revid-cli/main.go b/cmd/revid-cli/main.go
index 53f38833..5eca3ff7 100644
--- a/cmd/revid-cli/main.go
+++ b/cmd/revid-cli/main.go
@@ -106,32 +106,30 @@ func handleFlags() revid.Config {
 	var cfg revid.Config
 
 	var (
-		cpuprofile = flag.String("cpuprofile", "", "write cpu profile to `file`")
-
-		inputCodecPtr         = flag.String("InputCodec", "H264", "The codec of the input: H264, Mjpeg, PCM, ADPCM")
-		inputPtr              = flag.String("Input", "", "The input type: Raspivid, File, v4l, Audio, RTSP")
-		rtspURLPtr            = flag.String("RTSPURL", "", "The URL for an RTSP server.")
-		verbosityPtr          = flag.String("Verbosity", "Info", "Verbosity: Debug, Info, Warning, Error, Fatal")
-		rtpAddrPtr            = flag.String("RtpAddr", "", "Rtp destination address: <IP>:<port> (port is generally 6970-6999)")
-		logPathPtr            = flag.String("LogPath", defaultLogPath, "The log path")
-		configFilePtr         = flag.String("ConfigFile", "", "NetSender config file")
-		rtmpUrlPtr            = flag.String("RtmpUrl", "", "Url of rtmp endpoint")
-		outputPathPtr         = flag.String("OutputPath", "", "The directory of the output file")
-		inputFilePtr          = flag.String("InputPath", "", "The directory of the input file")
-		httpAddressPtr        = flag.String("HttpAddress", "", "Destination address of http posts")
-		verticalFlipPtr       = flag.Bool("VerticalFlip", false, "Flip video vertically: Yes, No")
-		horizontalFlipPtr     = flag.Bool("HorizontalFlip", false, "Flip video horizontally: Yes, No")
-		bitratePtr            = flag.Uint("Bitrate", 0, "Bitrate of recorded video")
-		heightPtr             = flag.Uint("Height", 0, "Height in pixels")
-		widthPtr              = flag.Uint("Width", 0, "Width in pixels")
-		frameRatePtr          = flag.Uint("FrameRate", 0, "Frame rate of captured video")
-		quantizationPtr       = flag.Uint("Quantization", 0, "Desired quantization value: 0-40")
-		intraRefreshPeriodPtr = flag.Uint("IntraRefreshPeriod", 0, "The IntraRefreshPeriod i.e. how many keyframes we send")
-		rotationPtr           = flag.Uint("Rotation", 0, "Rotate video output. (0-359 degrees)")
-		brightnessPtr         = flag.Uint("Brightness", 50, "Set brightness. (0-100) ")
-		saturationPtr         = flag.Int("Saturation", 0, "Set Saturation. (100-100)")
-		exposurePtr           = flag.String("Exposure", "auto", "Set exposure mode. ("+strings.Join(revid.ExposureModes[:], ",")+")")
-		autoWhiteBalancePtr   = flag.String("Awb", "auto", "Set automatic white balance mode. ("+strings.Join(revid.AutoWhiteBalanceModes[:], ",")+")")
+		cpuprofile          = flag.String("cpuprofile", "", "write cpu profile to `file`")
+		inputCodecPtr       = flag.String("InputCodec", "H264", "The codec of the input: H264, Mjpeg, PCM, ADPCM")
+		inputPtr            = flag.String("Input", "", "The input type: Raspivid, File, v4l, Audio, RTSP")
+		rtspURLPtr          = flag.String("RTSPURL", "", "The URL for an RTSP server.")
+		verbosityPtr        = flag.String("Verbosity", "Info", "Verbosity: Debug, Info, Warning, Error, Fatal")
+		rtpAddrPtr          = flag.String("RtpAddr", "", "Rtp destination address: <IP>:<port> (port is generally 6970-6999)")
+		logPathPtr          = flag.String("LogPath", defaultLogPath, "The log path")
+		configFilePtr       = flag.String("ConfigFile", "", "NetSender config file")
+		rtmpUrlPtr          = flag.String("RtmpUrl", "", "Url of rtmp endpoint")
+		outputPathPtr       = flag.String("OutputPath", "", "The directory of the output file")
+		inputFilePtr        = flag.String("InputPath", "", "The directory of the input file")
+		httpAddressPtr      = flag.String("HttpAddress", "", "Destination address of http posts")
+		verticalFlipPtr     = flag.Bool("VerticalFlip", false, "Flip video vertically: Yes, No")
+		horizontalFlipPtr   = flag.Bool("HorizontalFlip", false, "Flip video horizontally: Yes, No")
+		bitratePtr          = flag.Uint("Bitrate", 0, "Bitrate of recorded video")
+		heightPtr           = flag.Uint("Height", 0, "Height in pixels")
+		widthPtr            = flag.Uint("Width", 0, "Width in pixels")
+		frameRatePtr        = flag.Uint("FrameRate", 0, "Frame rate of captured video")
+		quantizationPtr     = flag.Uint("Quantization", 0, "Desired quantization value: 0-40")
+		rotationPtr         = flag.Uint("Rotation", 0, "Rotate video output. (0-359 degrees)")
+		brightnessPtr       = flag.Uint("Brightness", 50, "Set brightness. (0-100) ")
+		saturationPtr       = flag.Int("Saturation", 0, "Set Saturation. (100-100)")
+		exposurePtr         = flag.String("Exposure", "auto", "Set exposure mode. ("+strings.Join(revid.ExposureModes[:], ",")+")")
+		autoWhiteBalancePtr = flag.String("Awb", "auto", "Set automatic white balance mode. ("+strings.Join(revid.AutoWhiteBalanceModes[:], ",")+")")
 
 		// Audio specific flags.
 		sampleRatePtr = flag.Int("SampleRate", 48000, "Sample rate of recorded audio")
@@ -246,7 +244,6 @@ func handleFlags() revid.Config {
 	cfg.FrameRate = *frameRatePtr
 	cfg.HTTPAddress = *httpAddressPtr
 	cfg.Quantization = *quantizationPtr
-	cfg.IntraRefreshPeriod = *intraRefreshPeriodPtr
 	cfg.RTPAddress = *rtpAddrPtr
 	cfg.Brightness = *brightnessPtr
 	cfg.Saturation = *saturationPtr
diff --git a/codec/adpcm/adpcm.go b/codec/adpcm/adpcm.go
index ce8ae9f7..479f6261 100644
--- a/codec/adpcm/adpcm.go
+++ b/codec/adpcm/adpcm.go
@@ -40,10 +40,11 @@ import (
 const (
 	byteDepth     = 2 // We are working with 16-bit samples. TODO(Trek): make configurable.
 	initSamps     = 2 // Number of samples used to initialise the encoder.
-	initBytes     = initSamps * byteDepth
-	headBytes     = 4 // Number of bytes in the header of ADPCM.
+	initSize      = initSamps * byteDepth
+	headSize      = 8 // Number of bytes in the header of ADPCM.
 	samplesPerEnc = 2 // Number of sample encoded at a time eg. 2 16-bit samples get encoded into 1 byte.
 	bytesPerEnc   = samplesPerEnc * byteDepth
+	chunkLenSize  = 4 // Size of the chunk length in bytes, chunk length is a 32 bit number.
 	compFact      = 4 // In general ADPCM compresses by a factor of 4.
 )
 
@@ -176,7 +177,7 @@ func (e *Encoder) calcHead(sample []byte, pad bool) (int, error) {
 // The suitable step size is the closest step size in the stepTable to half the absolute difference of the first two samples.
 func (e *Encoder) init(samples []byte) {
 	int1 := int16(binary.LittleEndian.Uint16(samples[:byteDepth]))
-	int2 := int16(binary.LittleEndian.Uint16(samples[byteDepth:initBytes]))
+	int2 := int16(binary.LittleEndian.Uint16(samples[byteDepth:initSize]))
 	e.est = int1
 
 	halfDiff := math.Abs(math.Abs(float64(int1)) - math.Abs(float64(int2))/2)
@@ -197,8 +198,8 @@ func (e *Encoder) init(samples []byte) {
 func (e *Encoder) Write(b []byte) (int, error) {
 	// Check that pcm has enough data to initialize Decoder.
 	pcmLen := len(b)
-	if pcmLen < initBytes {
-		return 0, fmt.Errorf("length of given byte array must be >= %v", initBytes)
+	if pcmLen < initSize {
+		return 0, fmt.Errorf("length of given byte array must be >= %v", initSize)
 	}
 
 	// Determine if there will be a byte that won't contain two full nibbles and will need padding.
@@ -207,8 +208,18 @@ func (e *Encoder) Write(b []byte) (int, error) {
 		pad = true
 	}
 
-	e.init(b[:initBytes])
-	n, err := e.calcHead(b[:byteDepth], pad)
+	// Write the first 4 bytes of the adpcm chunk, which represent its length, ie. the number of bytes following the chunk length.
+	chunkLen := EncBytes(pcmLen)
+	chunkLenBytes := make([]byte, chunkLenSize)
+	binary.LittleEndian.PutUint32(chunkLenBytes, uint32(chunkLen))
+	n, err := e.dst.Write(chunkLenBytes)
+	if err != nil {
+		return n, err
+	}
+
+	e.init(b[:initSize])
+	_n, err := e.calcHead(b[:byteDepth], pad)
+	n += _n
 	if err != nil {
 		return n, err
 	}
@@ -284,47 +295,59 @@ func (d *Decoder) decodeSample(nibble byte) int16 {
 // It writes its output to the Decoder's dst.
 // The number of bytes written out is returned along with any error that occured.
 func (d *Decoder) Write(b []byte) (int, error) {
-	// Initialize Decoder with first 4 bytes of b.
-	d.est = int16(binary.LittleEndian.Uint16(b[:byteDepth]))
-	d.idx = int16(b[byteDepth])
-	d.step = stepTable[d.idx]
-	n, err := d.dst.Write(b[:byteDepth])
-	if err != nil {
-		return n, err
-	}
+	// Iterate over each chunk and decode it.
+	var n int
+	var chunkLen int
+	for off := 0; off+headSize <= len(b); off += chunkLen {
+		// Read length of chunk and check if whole chunk exists.
+		chunkLen = int(binary.LittleEndian.Uint32(b[off : off+chunkLenSize]))
+		if off+chunkLen > len(b) {
+			break
+		}
 
-	// For each byte, seperate it into two nibbles (each nibble is a compressed sample),
-	// then decode each nibble and output the resulting 16-bit samples.
-	// If padding flag is true (Adpcm[3]), only decode up until the last byte, then decode that separately.
-	for i := headBytes; i < len(b)-int(b[3]); i++ {
-		twoNibs := b[i]
-		nib2 := byte(twoNibs >> 4)
-		nib1 := byte((nib2 << 4) ^ twoNibs)
-
-		firstBytes := make([]byte, byteDepth)
-		binary.LittleEndian.PutUint16(firstBytes, uint16(d.decodeSample(nib1)))
-		_n, err := d.dst.Write(firstBytes)
+		// Initialize Decoder with header of b.
+		d.est = int16(binary.LittleEndian.Uint16(b[off+chunkLenSize : off+chunkLenSize+byteDepth]))
+		d.idx = int16(b[off+chunkLenSize+byteDepth])
+		d.step = stepTable[d.idx]
+		_n, err := d.dst.Write(b[off+chunkLenSize : off+chunkLenSize+byteDepth])
 		n += _n
 		if err != nil {
 			return n, err
 		}
 
-		secondBytes := make([]byte, byteDepth)
-		binary.LittleEndian.PutUint16(secondBytes, uint16(d.decodeSample(nib2)))
-		_n, err = d.dst.Write(secondBytes)
-		n += _n
-		if err != nil {
-			return n, err
+		// For each byte, seperate it into two nibbles (each nibble is a compressed sample),
+		// then decode each nibble and output the resulting 16-bit samples.
+		// If padding flag is true only decode up until the last byte, then decode that separately.
+		for i := off + headSize; i < off+chunkLen-int(b[off+chunkLenSize+3]); i++ {
+			twoNibs := b[i]
+			nib2 := byte(twoNibs >> 4)
+			nib1 := byte((nib2 << 4) ^ twoNibs)
+
+			firstBytes := make([]byte, byteDepth)
+			binary.LittleEndian.PutUint16(firstBytes, uint16(d.decodeSample(nib1)))
+			_n, err := d.dst.Write(firstBytes)
+			n += _n
+			if err != nil {
+				return n, err
+			}
+
+			secondBytes := make([]byte, byteDepth)
+			binary.LittleEndian.PutUint16(secondBytes, uint16(d.decodeSample(nib2)))
+			_n, err = d.dst.Write(secondBytes)
+			n += _n
+			if err != nil {
+				return n, err
+			}
 		}
-	}
-	if b[3] == 0x01 {
-		padNib := b[len(b)-1]
-		samp := make([]byte, byteDepth)
-		binary.LittleEndian.PutUint16(samp, uint16(d.decodeSample(padNib)))
-		_n, err := d.dst.Write(samp)
-		n += _n
-		if err != nil {
-			return n, err
+		if b[off+chunkLenSize+3] == 0x01 {
+			padNib := b[off+chunkLen-1]
+			samp := make([]byte, byteDepth)
+			binary.LittleEndian.PutUint16(samp, uint16(d.decodeSample(padNib)))
+			_n, err := d.dst.Write(samp)
+			n += _n
+			if err != nil {
+				return n, err
+			}
 		}
 	}
 	return n, nil
@@ -349,7 +372,7 @@ func EncBytes(n int) int {
 	// and a start index and padding-flag byte are added.
 	// Also if there are an even number of samples, there will be half a byte of padding added to the last byte.
 	if n%bytesPerEnc == 0 {
-		return (n-byteDepth)/compFact + headBytes + 1
+		return (n-byteDepth)/compFact + headSize + 1
 	}
-	return (n-byteDepth)/compFact + headBytes
+	return (n-byteDepth)/compFact + headSize
 }
diff --git a/codec/adpcm/adpcm_test.go b/codec/adpcm/adpcm_test.go
index 8b825696..0afde670 100644
--- a/codec/adpcm/adpcm_test.go
+++ b/codec/adpcm/adpcm_test.go
@@ -51,7 +51,7 @@ func TestEncodeBlock(t *testing.T) {
 	}
 
 	// Read expected adpcm file.
-	exp, err := ioutil.ReadFile("../../../test/test-data/av/output/encoded_8kHz_adpcm_test.adpcm")
+	exp, err := ioutil.ReadFile("../../../test/test-data/av/output/encoded_8kHz_adpcm_test2.adpcm")
 	if err != nil {
 		t.Errorf("Unable to read expected ADPCM file: %v", err)
 	}
@@ -65,7 +65,7 @@ func TestEncodeBlock(t *testing.T) {
 // resulting PCM with the expected decoded PCM.
 func TestDecodeBlock(t *testing.T) {
 	// Read adpcm.
-	comp, err := ioutil.ReadFile("../../../test/test-data/av/input/encoded_8kHz_adpcm_test.adpcm")
+	comp, err := ioutil.ReadFile("../../../test/test-data/av/input/encoded_8kHz_adpcm_test2.adpcm")
 	if err != nil {
 		t.Errorf("Unable to read input ADPCM file: %v", err)
 	}
@@ -79,7 +79,7 @@ func TestDecodeBlock(t *testing.T) {
 	}
 
 	// Read expected pcm file.
-	exp, err := ioutil.ReadFile("../../../test/test-data/av/output/decoded_8kHz_adpcm_test.pcm")
+	exp, err := ioutil.ReadFile("../../../test/test-data/av/output/decoded_8kHz_adpcm_test2.pcm")
 	if err != nil {
 		t.Errorf("Unable to read expected PCM file: %v", err)
 	}
diff --git a/codec/h264/h264dec/cabac.go b/codec/h264/h264dec/cabac.go
index b5940a00..7b28414e 100644
--- a/codec/h264/h264dec/cabac.go
+++ b/codec/h264/h264dec/cabac.go
@@ -28,8 +28,6 @@ LICENSE
 package h264dec
 
 import (
-	"math"
-
 	"bitbucket.org/ausocean/av/codec/h264/h264dec/bits"
 	"github.com/pkg/errors"
 )
@@ -306,80 +304,6 @@ var (
 	}
 )
 
-// Errors used by mbTypeBinarization.
-var (
-	errBadMbType      = errors.New("macroblock type outside of valid range")
-	errBadMbSliceType = errors.New("bad slice type for macroblock")
-)
-
-// mbTypeBinarization returns the macroblock type binarization for the given
-// macroblock type value and slice type using the process defined in section
-// 9.3.2.5 of the specifications.
-func mbTypeBinarization(v, slice int) ([]int, error) {
-	switch slice {
-	case sliceTypeI:
-		if v < minIMbType || v > maxIMbType {
-			return nil, errBadMbType
-		}
-		return binOfIMBTypes[v], nil
-
-	case sliceTypeSI:
-		if v < minSIMbType || v > maxSIMbType {
-			return nil, errBadMbType
-		}
-		if v == sliceTypeSI {
-			return []int{0}, nil
-		}
-		return append([]int{1}, binOfIMBTypes[v-1]...), nil
-
-	case sliceTypeP, sliceTypeSP:
-		if v < minPOrSPMbType || v > maxPOrSPMbType || v == P8x8ref0 {
-			return nil, errBadMbType
-		}
-		if v < 5 {
-			return binOfPOrSPMBTypes[v], nil
-		}
-		return append([]int{1}, binOfIMBTypes[v-5]...), nil
-
-	case sliceTypeB:
-		if v < minBMbType || v > maxBMbType {
-			return nil, errBadMbType
-		}
-		if v < 23 {
-			return binOfBMBTypes[v], nil
-		}
-		return append([]int{1, 1, 1, 1, 0, 1}, binOfIMBTypes[v-23]...), nil
-
-	default:
-		return nil, errBadMbSliceType
-	}
-}
-
-// Error used by subMbTypeBinarization.
-var errBadSubMbSliceType = errors.New("bad slice type for sub-macroblock")
-
-// subMbTypeBinarization returns the binarization of a sub-macroblock type
-// given the slice in which it is in using the process defined in section
-// 9.3.2.5 of the specifications.
-func subMbTypeBinarization(v, slice int) ([]int, error) {
-	switch slice {
-	case sliceTypeP, sliceTypeSP:
-		if v < minPOrSPSubMbType || v > maxPOrSPSubMbType {
-			return nil, errBadMbType
-		}
-		return binOfPOrSPSubMBTypes[v], nil
-
-	case sliceTypeB:
-		if v < minBSubMbType || v > maxBSubMbType {
-			return nil, errBadMbType
-		}
-		return binOfBSubMBTypes[v], nil
-
-	default:
-		return nil, errBadSubMbSliceType
-	}
-}
-
 // Table 9-34
 type MaxBinIdxCtx struct {
 	// When false, Prefix is the MaxBinIdxCtx
@@ -762,119 +686,3 @@ func CtxIdx(binIdx, maxBinIdxCtx, ctxIdxOffset int) int {
 
 	return ctxIdx
 }
-
-// Error used by unaryBinarization.
-var errNegativeSyntaxVal = errors.New("cannot get unary binarization of negative value")
-
-// unaryBinarization returns the unary binarization of a syntax element having
-// value v, as specified by setion 9.3.2.1 in the specifications.
-func unaryBinarization(v int) ([]int, error) {
-	if v < 0 {
-		return nil, errNegativeSyntaxVal
-	}
-	r := make([]int, v+1)
-	for i := 0; i <= v; i++ {
-		if i < v {
-			r[i] = 1
-		}
-	}
-	return r, nil
-}
-
-// Error used by truncUnaryBinarization.
-var errInvalidSyntaxVal = errors.New("syntax value cannot be greater than cMax")
-
-// truncUnaryBinarization returns the truncated unary binarization of a syntax
-// element v given a cMax as specified in section 9.3.2.2 of the specifications.
-func truncUnaryBinarization(v, cMax int) ([]int, error) {
-	if v < 0 {
-		return nil, errNegativeSyntaxVal
-	}
-
-	if v > cMax {
-		return nil, errInvalidSyntaxVal
-	}
-
-	if v == cMax {
-		b, _ := unaryBinarization(v)
-		return b[:len(b)-1], nil
-	}
-	return unaryBinarization(v)
-}
-
-// Error used by unaryExpGolombBinarization.
-var errInvalidUCoff = errors.New("uCoff cannot be less than or equal to zero")
-
-// unaryExpGolombBinarization returns the concatendated unary/k-th order
-// Exp-Golomb (UEGk) binarization of a syntax element using the process defined
-// in section 9.3.2.3 of the specifications.
-func unaryExpGolombBinarization(v, uCoff, k int, signedValFlag bool) ([]int, error) {
-	if uCoff <= 0 {
-		return nil, errInvalidUCoff
-	}
-
-	prefix, err := truncUnaryBinarization(mini(uCoff, absi(v)), uCoff)
-	if err != nil {
-		return nil, err
-	}
-
-	return append(prefix, suffix(v, uCoff, k, signedValFlag)...), nil
-}
-
-// suffix returns the suffix part of a unary k-th Exp-Golomb Binarization
-// using the the algorithm as described by pseudo code 9-6 in section 9.3.2.3.
-// TODO: could probably reduce allocations.
-func suffix(v, uCoff, k int, signedValFlag bool) []int {
-	var s []int
-
-	if absi(v) >= uCoff {
-		sufS := absi(v) - uCoff
-		var stop bool
-
-		for {
-			if sufS >= (1 << uint(k)) {
-				s = append(s, 1)
-				sufS = sufS - (1 << uint(k))
-				k++
-			} else {
-				s = append(s, 0)
-				for k = k - 1; k >= 0; k-- {
-					s = append(s, (sufS>>uint(k))&1)
-				}
-				stop = true
-			}
-			if stop {
-				break
-			}
-		}
-	}
-
-	if signedValFlag && v != 0 {
-		if v > 0 {
-			s = append(s, 0)
-		} else {
-			s = append(s, 1)
-		}
-	}
-
-	return s
-}
-
-// Error used by fixedLenBinariztion.
-var errNegativeValue = errors.New("cannot get fixed length binarization of negative value")
-
-// fixedLenBinarization returns the fixed-length (FL) binarization of the syntax
-// element v, given cMax to determine bin length, as specified by section 9.3.2.4
-// of the specifications.
-func fixedLenBinarization(v, cMax int) ([]int, error) {
-	if v < 0 {
-		return nil, errNegativeValue
-	}
-	l := int(math.Ceil(math.Log2(float64(cMax + 1))))
-	r := make([]int, l)
-	for i := l - 1; i >= 0; i-- {
-		r[i] = v % 2
-		v = v / 2
-	}
-	return r, nil
-}
diff --git a/codec/h264/h264dec/cabac_test.go b/codec/h264/h264dec/cabac_test.go
index 5ca17ce8..20f1e066 100644
--- a/codec/h264/h264dec/cabac_test.go
+++ b/codec/h264/h264dec/cabac_test.go
@@ -26,74 +26,9 @@ LICENSE
 package h264dec
 
 import (
-	"reflect"
 	"testing"
 )
 
-func TestMbTypeBinarization(t *testing.T) {
-	tests := []struct {
-		v, slice int
-		want     []int
-		err      error
-	}{
-		{v: 6, slice: sliceTypeI, want: []int{1, 0, 0, 1, 0, 0, 1}},
-		{v: 26, slice: sliceTypeI, err: errBadMbType},
-		{v: -1, slice: sliceTypeI, err: errBadMbType},
-		{v: 4, slice: sliceTypeSI, want: []int{0}},
-		{v: 6, slice: sliceTypeSI, want: []int{1, 1, 0, 0, 1, 0, 0, 0}},
-		{v: 0, slice: sliceTypeSI, err: errBadMbType},
-		{v: 27, slice: sliceTypeSI, err: errBadMbType},
-		{v: 2, slice: sliceTypeP, want: []int{0, 1, 0}},
-		{v: 3, slice: sliceTypeSP, want: []int{0, 0, 1}},
-		{v: 7, slice: sliceTypeP, want: []int{1, 1, 0, 0, 0, 0, 1}},
-		{v: 7, slice: sliceTypeSP, want: []int{1, 1, 0, 0, 0, 0, 1}},
-		{v: -1, slice: sliceTypeP, err: errBadMbType},
-		{v: 31, slice: sliceTypeP, err: errBadMbType},
-		{v: 8, slice: sliceTypeB, want: []int{1, 1, 0, 1, 0, 1}},
-		{v: 30, slice: sliceTypeB, want: []int{1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0}},
-		{v: -1, slice: sliceTypeB, err: errBadMbType},
-		{v: 49, slice: sliceTypeB, err: errBadMbType},
-		{v: 6, slice: 20, err: errBadMbSliceType},
-	}
-
-	for i, test := range tests {
-		got, err := mbTypeBinarization(test.v, test.slice)
-		if err != test.err {
-			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
-		}
-
-		if !reflect.DeepEqual(got, test.want) {
-			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v", i, got, test.want)
-		}
-	}
-}
-
-func TestSubMbTypeBinarization(t *testing.T) {
-	tests := []struct {
-		v, slice int
-		want     []int
-		err      error
-	}{
-		{v: 2, slice: sliceTypeP, want: []int{0, 1, 1}},
-		{v: 2, slice: sliceTypeSP, want: []int{0, 1, 1}},
-		{v: -1, slice: sliceTypeSP, err: errBadMbType},
-		{v: 4, slice: sliceTypeSP, err: errBadMbType},
-		{v: 9, slice: sliceTypeB, want: []int{1, 1, 1, 0, 1, 0}},
-		{v: 9, slice: 40, err: errBadSubMbSliceType},
-	}
-
-	for i, test := range tests {
-		got, err := subMbTypeBinarization(test.v, test.slice)
-		if err != test.err {
-			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
-		}
-
-		if !reflect.DeepEqual(got, test.want) {
-			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v", i, got, test.want)
-		}
-	}
-}
-
 var ctxIdxTests = []struct {
 	binIdx       int
 	maxBinIdxCtx int
@@ -211,144 +146,3 @@ func TestCtxIdx(t *testing.T) {
 		}
 	}
 }
-
-func TestUnaryBinarization(t *testing.T) {
-	// Test data has been extracted from table 9-35 of the specifications.
-	tests := []struct {
-		in   int
-		want []int
-		err  error
-	}{
-		{in: 0, want: []int{0}, err: nil},
-		{in: 1, want: []int{1, 0}, err: nil},
-		{in: 2, want: []int{1, 1, 0}, err: nil},
-		{in: 3, want: []int{1, 1, 1, 0}, err: nil},
-		{in: 4, want: []int{1, 1, 1, 1, 0}, err: nil},
-		{in: 5, want: []int{1, 1, 1, 1, 1, 0}, err: nil},
-		{in: -3, want: nil, err: errNegativeSyntaxVal},
-	}
-
-	for i, test := range tests {
-		got, err := unaryBinarization(test.in)
-		if err != test.err {
-			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
-		}
-
-		if !reflect.DeepEqual(test.want, got) {
-			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
-		}
-	}
-}
-
-func TestFixedLengthBinarization(t *testing.T) {
-	tests := []struct {
-		v    int
-		cMax int
-		want []int
-		err  error
-	}{
-		{v: 0, cMax: 7, want: []int{0, 0, 0}},
-		{v: 1, cMax: 7, want: []int{0, 0, 1}},
-		{v: 2, cMax: 7, want: []int{0, 1, 0}},
-		{v: 3, cMax: 7, want: []int{0, 1, 1}},
-		{v: 4, cMax: 7, want: []int{1, 0, 0}},
-		{v: 5, cMax: 7, want: []int{1, 0, 1}},
-		{v: 6, cMax: 7, want: []int{1, 1, 0}},
-		{v: 7, cMax: 7, want: []int{1, 1, 1}},
-		{v: -1, cMax: 7, want: nil, err: errNegativeValue},
-	}
-
-	for i, test := range tests {
-		got, err := fixedLenBinarization(test.v, test.cMax)
-		if err != test.err {
-			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v\n", i, err, test.err)
-		}
-
-		if !reflect.DeepEqual(test.want, got) {
-			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
-		}
-	}
-}
-
-func TestTruncUnaryBinarization(t *testing.T) {
-	tests := []struct {
-		v    int
-		cMax int
-		want []int
-		err  error
-	}{
-		{v: 0, cMax: 10, want: []int{0}, err: nil},
-		{v: 1, cMax: 10, want: []int{1, 0}, err: nil},
-		{v: 2, cMax: 10, want: []int{1, 1, 0}, err: nil},
-		{v: 0, cMax: 0, want: []int{}, err: nil},
-		{v: 4, cMax: 4, want: []int{1, 1, 1, 1}, err: nil},
-		{v: 1, cMax: 10, want: []int{1, 0}, err: nil},
-		{v: 2, cMax: 10, want: []int{1, 1, 0}, err: nil},
-		{v: -3, cMax: 10, want: nil, err: errNegativeSyntaxVal},
-		{v: 5, cMax: 4, want: nil, err: errInvalidSyntaxVal},
-	}
-
-	for i, test := range tests {
-		got, err := truncUnaryBinarization(test.v, test.cMax)
-		if err != test.err {
-			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
-		}
-
-		if !reflect.DeepEqual(test.want, got) {
-			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
-		}
-	}
-}
-
-func TestUEGkSuffix(t *testing.T) {
-	// Data from https://patents.google.com/patent/US20070092150
-	tests := []struct {
-		v, uCoff, k   int
-		signedValFlag bool
-		want          []int
-	}{
-		0:  {v: 14, uCoff: 14, want: []int{0}},
-		1:  {v: 15, uCoff: 14, want: []int{1, 0, 0}},
-		2:  {v: 16, uCoff: 14, want: []int{1, 0, 1}},
-		3:  {v: 17, uCoff: 14, want: []int{1, 1, 0, 0, 0}},
-		4:  {v: 18, uCoff: 14, want: []int{1, 1, 0, 0, 1}},
-		5:  {v: 19, uCoff: 14, want: []int{1, 1, 0, 1, 0}},
-		6:  {v: 20, uCoff: 14, want: []int{1, 1, 0, 1, 1}},
-		7:  {v: 21, uCoff: 14, want: []int{1, 1, 1, 0, 0, 0, 0}},
-		8:  {v: 22, uCoff: 14, want: []int{1, 1, 1, 0, 0, 0, 1}},
-		9:  {v: 23, uCoff: 14, want: []int{1, 1, 1, 0, 0, 1, 0}},
-		10: {v: 24, uCoff: 14, want: []int{1, 1, 1, 0, 0, 1, 1}},
-		11: {v: 25, uCoff: 14, want: []int{1, 1, 1, 0, 1, 0, 0}},
-	}
-
-	for i, test := range tests {
-		got := suffix(test.v, test.uCoff, test.k, test.signedValFlag)
-		if !reflect.DeepEqual(got, test.want) {
-			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
-		}
-	}
-}
-
-func TestUnaryExpGolombBinarization(t *testing.T) {
-	tests := []struct {
-		v, uCoff, k   int
-		signedValFlag bool
-		want          []int
-	}{
-		0: {v: 7, uCoff: 14, want: []int{1, 1, 1, 1, 1, 1, 1, 0}},
-		1: {v: 17, uCoff: 14, want: []int{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0}},
-		2: {v: 15, uCoff: 14, signedValFlag: true, want: []int{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0}},
-		3: {v: -15, uCoff: 14, signedValFlag: true, want: []int{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1}},
-	}
-
-	for i, test := range tests {
-		got, err := unaryExpGolombBinarization(test.v, test.uCoff, test.k, test.signedValFlag)
-		if err != nil {
-			t.Errorf("did not expect error %v for test %d", err, i)
-		}
-
-		if !reflect.DeepEqual(got, test.want) {
-			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
-		}
-	}
-}
diff --git a/codec/h264/h264dec/cabacenc.go b/codec/h264/h264dec/cabacenc.go
new file mode 100644
index 00000000..f9b0cca5
--- /dev/null
+++ b/codec/h264/h264dec/cabacenc.go
@@ -0,0 +1,243 @@
+/*
+TODO: this file should really be in a 'h264enc' package.
+
+DESCRIPTION
+  cabacenc.go provides functionality for CABAC encoding.
+
+AUTHORS
+  Saxon A. Nelson-Milton <saxon@ausocean.org>
+
+LICENSE
+  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
+  Free Software Foundation, either version 3 of the License, or (at your
+  option) any later version.
+
+  It is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+  for more details.
+
+  You should have received a copy of the GNU General Public License
+  in gpl.txt.  If not, see http://www.gnu.org/licenses.
+*/
+
+package h264dec
+
+import (
+	"errors"
+	"fmt"
+	"math"
+)
+
+// Error used by unaryBinString.
+var errNegativeSyntaxVal = errors.New("cannot get unary binary string of negative value")
+
+// unaryBinString returns the unary binary string of a syntax element having
+// value v, as specified by setion 9.3.2.1 in the specifications.
+func unaryBinString(v int) ([]int, error) {
+	if v < 0 {
+		return nil, errNegativeSyntaxVal
+	}
+	r := make([]int, v+1)
+	for i := 0; i <= v; i++ {
+		if i < v {
+			r[i] = 1
+		}
+	}
+	return r, nil
+}
+
+// Error used by truncUnaryBinString.
+var errInvalidSyntaxVal = errors.New("syntax value cannot be greater than cMax")
+
+// truncUnaryBinString returns the truncated unary binary string of a syntax
+// element v given a cMax as specified in section 9.3.2.2 of the specifications.
+func truncUnaryBinString(v, cMax int) ([]int, error) {
+	if v < 0 {
+		return nil, errNegativeSyntaxVal
+	}
+
+	if v > cMax {
+		return nil, errInvalidSyntaxVal
+	}
+
+	if v == cMax {
+		b, _ := unaryBinString(v)
+		return b[:len(b)-1], nil
+	}
+	return unaryBinString(v)
+}
+
+// Error used by unaryExpGolombBinString.
+var errInvalidUCoff = errors.New("uCoff cannot be less than or equal to zero")
+
+// unaryExpGolombBinString returns the concatendated unary/k-th order
+// Exp-Golomb (UEGk) binary string of a syntax element using the process defined
+// in section 9.3.2.3 of the specifications.
+func unaryExpGolombBinString(v, uCoff, k int, signedValFlag bool) ([]int, error) {
+	if uCoff <= 0 {
+		return nil, errInvalidUCoff
+	}
+
+	prefix, err := truncUnaryBinString(mini(uCoff, absi(v)), uCoff)
+	if err != nil {
+		return nil, err
+	}
+
+	return append(prefix, suffix(v, uCoff, k, signedValFlag)...), nil
+}
+
+// suffix returns the suffix part of a unary k-th Exp-Golomb binar string
+// using the the algorithm as described by pseudo code 9-6 in section 9.3.2.3.
+// TODO: could probably reduce allocations.
+func suffix(v, uCoff, k int, signedValFlag bool) []int {
+	var s []int
+
+	if absi(v) >= uCoff {
+		sufS := absi(v) - uCoff
+		var stop bool
+
+		for {
+			if sufS >= (1 << uint(k)) {
+				s = append(s, 1)
+				sufS = sufS - (1 << uint(k))
+				k++
+			} else {
+				s = append(s, 0)
+				for k = k - 1; k >= 0; k-- {
+					s = append(s, (sufS>>uint(k))&1)
+				}
+				stop = true
+			}
+			if stop {
+				break
+			}
+		}
+	}
+
+	if signedValFlag && v != 0 {
+		if v > 0 {
+			s = append(s, 0)
+		} else {
+			s = append(s, 1)
+		}
+	}
+
+	return s
+}
+
+// Error used by fixedLenBinString.
+var errNegativeValue = errors.New("cannot get fixed length binary string of negative value")
+
+// fixedLenBinString returns the fixed-length (FL) binary string of the syntax
+// element v, given cMax to determine bin length, as specified by section 9.3.2.4
+// of the specifications.
+func fixedLenBinString(v, cMax int) ([]int, error) {
+	if v < 0 {
+		return nil, errNegativeValue
+	}
+	l := int(math.Ceil(math.Log2(float64(cMax + 1))))
+	r := make([]int, l)
+	for i := l - 1; i >= 0; i-- {
+		r[i] = v % 2
+		v = v / 2
+	}
+	return r, nil
+}
+
+// Errors used by mbTypeBinString.
+var (
+	errBadMbType      = errors.New("macroblock type outside of valid range")
+	errBadMbSliceType = errors.New("bad slice type for macroblock")
+)
+
+// mbTypeBinString returns the macroblock type binary string for the given
+// macroblock type value and slice type using the process defined in section
+// 9.3.2.5 of the specifications.
+func mbTypeBinString(v, slice int) ([]int, error) {
+	switch slice {
+	case sliceTypeI:
+		if v < minIMbType || v > maxIMbType {
+			return nil, errBadMbType
+		}
+		return binOfIMBTypes[v], nil
+
+	case sliceTypeSI:
+		if v < minSIMbType || v > maxSIMbType {
+			return nil, errBadMbType
+		}
+		if v == sliceTypeSI {
+			return []int{0}, nil
+		}
+		return append([]int{1}, binOfIMBTypes[v-1]...), nil
+
+	case sliceTypeP, sliceTypeSP:
+		if v < minPOrSPMbType || v > maxPOrSPMbType || v == P8x8ref0 {
+			return nil, errBadMbType
+		}
+		if v < 5 {
+			return binOfPOrSPMBTypes[v], nil
+		}
+		return append([]int{1}, binOfIMBTypes[v-5]...), nil
+
+	case sliceTypeB:
+		if v < minBMbType || v > maxBMbType {
+			return nil, errBadMbType
+		}
+		if v < 23 {
+			return binOfBMBTypes[v], nil
+		}
+		return append([]int{1, 1, 1, 1, 0, 1}, binOfIMBTypes[v-23]...), nil
+
+	default:
+		return nil, errBadMbSliceType
+	}
+}
+
+// Error used by subMbTypeBinString.
+var errBadSubMbSliceType = errors.New("bad slice type for sub-macroblock")
+
+// subMbTypeBinString returns the binary string of a sub-macroblock type
+// given the slice in which it is in using the process defined in section
+// 9.3.2.5 of the specifications.
+func subMbTypeBinString(v, slice int) ([]int, error) {
+	switch slice {
+	case sliceTypeP, sliceTypeSP:
+		if v < minPOrSPSubMbType || v > maxPOrSPSubMbType {
+			return nil, errBadMbType
+		}
+		return binOfPOrSPSubMBTypes[v], nil
+
+	case sliceTypeB:
+		if v < minBSubMbType || v > maxBSubMbType {
+			return nil, errBadMbType
+		}
+		return binOfBSubMBTypes[v], nil
+
+	default:
+		return nil, errBadSubMbSliceType
+	}
+}
+
+// codedBlockPatternBinString returns the binarization for the syntax element
+// coded_block_pattern as defined by section 9.3.2.6 in specifications.
+func codedBlockPatternBinString(luma, chroma, arrayType int) ([]int, error) {
+	p, err := fixedLenBinString(luma, 15)
+	if err != nil {
+		return nil, fmt.Errorf("fixed length binarization failed with error: %v", err)
+	}
+
+	if arrayType == 0 || arrayType == 3 {
+		return p, nil
+	}
+
+	s, err := truncUnaryBinString(chroma, 2)
+	if err != nil {
+		return nil, fmt.Errorf("truncated unary binarization failed with error: %v", err)
+	}
+
+	return append(p, s...), nil
+}
diff --git a/codec/h264/h264dec/cabacenc_test.go b/codec/h264/h264dec/cabacenc_test.go
new file mode 100644
index 00000000..d27b1624
--- /dev/null
+++ b/codec/h264/h264dec/cabacenc_test.go
@@ -0,0 +1,237 @@
+/*
+TODO: this file should really be in a 'h264enc' package.
+
+DESCRIPTION
+  cabacenc_test.go provides testing for functionality found in cabacenc.go.
+
+AUTHORS
+  Saxon A. Nelson-Milton <saxon@ausocean.org>
+
+LICENSE
+  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
+  Free Software Foundation, either version 3 of the License, or (at your
+  option) any later version.
+
+  It is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+  for more details.
+
+  You should have received a copy of the GNU General Public License
+  in gpl.txt.  If not, see http://www.gnu.org/licenses.
+*/
+
+package h264dec
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestMbTypeBinString(t *testing.T) {
+	tests := []struct {
+		v, slice int
+		want     []int
+		err      error
+	}{
+		{v: 6, slice: sliceTypeI, want: []int{1, 0, 0, 1, 0, 0, 1}},
+		{v: 26, slice: sliceTypeI, err: errBadMbType},
+		{v: -1, slice: sliceTypeI, err: errBadMbType},
+		{v: 4, slice: sliceTypeSI, want: []int{0}},
+		{v: 6, slice: sliceTypeSI, want: []int{1, 1, 0, 0, 1, 0, 0, 0}},
+		{v: 0, slice: sliceTypeSI, err: errBadMbType},
+		{v: 27, slice: sliceTypeSI, err: errBadMbType},
+		{v: 2, slice: sliceTypeP, want: []int{0, 1, 0}},
+		{v: 3, slice: sliceTypeSP, want: []int{0, 0, 1}},
+		{v: 7, slice: sliceTypeP, want: []int{1, 1, 0, 0, 0, 0, 1}},
+		{v: 7, slice: sliceTypeSP, want: []int{1, 1, 0, 0, 0, 0, 1}},
+		{v: -1, slice: sliceTypeP, err: errBadMbType},
+		{v: 31, slice: sliceTypeP, err: errBadMbType},
+		{v: 8, slice: sliceTypeB, want: []int{1, 1, 0, 1, 0, 1}},
+		{v: 30, slice: sliceTypeB, want: []int{1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0}},
+		{v: -1, slice: sliceTypeB, err: errBadMbType},
+		{v: 49, slice: sliceTypeB, err: errBadMbType},
+		{v: 6, slice: 20, err: errBadMbSliceType},
+	}
+
+	for i, test := range tests {
+		got, err := mbTypeBinString(test.v, test.slice)
+		if err != test.err {
+			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
+		}
+
+		if !reflect.DeepEqual(got, test.want) {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v", i, got, test.want)
+		}
+	}
+}
+
+func TestSubMbTypeBinString(t *testing.T) {
+	tests := []struct {
+		v, slice int
+		want     []int
+		err      error
+	}{
+		{v: 2, slice: sliceTypeP, want: []int{0, 1, 1}},
+		{v: 2, slice: sliceTypeSP, want: []int{0, 1, 1}},
+		{v: -1, slice: sliceTypeSP, err: errBadMbType},
+		{v: 4, slice: sliceTypeSP, err: errBadMbType},
+		{v: 9, slice: sliceTypeB, want: []int{1, 1, 1, 0, 1, 0}},
+		{v: 9, slice: 40, err: errBadSubMbSliceType},
+	}
+
+	for i, test := range tests {
+		got, err := subMbTypeBinString(test.v, test.slice)
+		if err != test.err {
+			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
+		}
+
+		if !reflect.DeepEqual(got, test.want) {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v", i, got, test.want)
+		}
+	}
+}
+
+func TestUnaryBinString(t *testing.T) {
+	// Test data has been extracted from table 9-35 of the specifications.
+	tests := []struct {
+		in   int
+		want []int
+		err  error
+	}{
+		{in: 0, want: []int{0}, err: nil},
+		{in: 1, want: []int{1, 0}, err: nil},
+		{in: 2, want: []int{1, 1, 0}, err: nil},
+		{in: 3, want: []int{1, 1, 1, 0}, err: nil},
+		{in: 4, want: []int{1, 1, 1, 1, 0}, err: nil},
+		{in: 5, want: []int{1, 1, 1, 1, 1, 0}, err: nil},
+		{in: -3, want: nil, err: errNegativeSyntaxVal},
+	}
+
+	for i, test := range tests {
+		got, err := unaryBinString(test.in)
+		if err != test.err {
+			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
+		}
+
+		if !reflect.DeepEqual(test.want, got) {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
+		}
+	}
+}
+
+func TestFixedLengthBinString(t *testing.T) {
+	tests := []struct {
+		v    int
+		cMax int
+		want []int
+		err  error
+	}{
+		{v: 0, cMax: 7, want: []int{0, 0, 0}},
+		{v: 1, cMax: 7, want: []int{0, 0, 1}},
+		{v: 2, cMax: 7, want: []int{0, 1, 0}},
+		{v: 3, cMax: 7, want: []int{0, 1, 1}},
+		{v: 4, cMax: 7, want: []int{1, 0, 0}},
+		{v: 5, cMax: 7, want: []int{1, 0, 1}},
+		{v: 6, cMax: 7, want: []int{1, 1, 0}},
+		{v: 7, cMax: 7, want: []int{1, 1, 1}},
+		{v: -1, cMax: 7, want: nil, err: errNegativeValue},
+	}
+
+	for i, test := range tests {
+		got, err := fixedLenBinString(test.v, test.cMax)
+		if err != test.err {
+			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v\n", i, err, test.err)
+		}
+
+		if !reflect.DeepEqual(test.want, got) {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
+		}
+	}
+}
+
+func TestTruncUnaryBinString(t *testing.T) {
+	tests := []struct {
+		v    int
+		cMax int
+		want []int
+		err  error
+	}{
+		{v: 0, cMax: 10, want: []int{0}, err: nil},
+		{v: 1, cMax: 10, want: []int{1, 0}, err: nil},
+		{v: 2, cMax: 10, want: []int{1, 1, 0}, err: nil},
+		{v: 0, cMax: 0, want: []int{}, err: nil},
+		{v: 4, cMax: 4, want: []int{1, 1, 1, 1}, err: nil},
+		{v: 1, cMax: 10, want: []int{1, 0}, err: nil},
+		{v: 2, cMax: 10, want: []int{1, 1, 0}, err: nil},
+		{v: -3, cMax: 10, want: nil, err: errNegativeSyntaxVal},
+		{v: 5, cMax: 4, want: nil, err: errInvalidSyntaxVal},
+	}
+
+	for i, test := range tests {
+		got, err := truncUnaryBinString(test.v, test.cMax)
+		if err != test.err {
+			t.Errorf("did not get expected error for test %d\nGot: %v\nWant: %v", i, err, test.err)
+		}
+
+		if !reflect.DeepEqual(test.want, got) {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
+		}
+	}
+}
+
+func TestUEGkSuffix(t *testing.T) {
+	// Data from https://patents.google.com/patent/US20070092150
+	tests := []struct {
+		v, uCoff, k   int
+		signedValFlag bool
+		want          []int
+	}{
+		0:  {v: 14, uCoff: 14, want: []int{0}},
+		1:  {v: 15, uCoff: 14, want: []int{1, 0, 0}},
+		2:  {v: 16, uCoff: 14, want: []int{1, 0, 1}},
+		3:  {v: 17, uCoff: 14, want: []int{1, 1, 0, 0, 0}},
+		4:  {v: 18, uCoff: 14, want: []int{1, 1, 0, 0, 1}},
+		5:  {v: 19, uCoff: 14, want: []int{1, 1, 0, 1, 0}},
+		6:  {v: 20, uCoff: 14, want: []int{1, 1, 0, 1, 1}},
+		7:  {v: 21, uCoff: 14, want: []int{1, 1, 1, 0, 0, 0, 0}},
+		8:  {v: 22, uCoff: 14, want: []int{1, 1, 1, 0, 0, 0, 1}},
+		9:  {v: 23, uCoff: 14, want: []int{1, 1, 1, 0, 0, 1, 0}},
+		10: {v: 24, uCoff: 14, want: []int{1, 1, 1, 0, 0, 1, 1}},
+		11: {v: 25, uCoff: 14, want: []int{1, 1, 1, 0, 1, 0, 0}},
+	}
+
+	for i, test := range tests {
+		got := suffix(test.v, test.uCoff, test.k, test.signedValFlag)
+		if !reflect.DeepEqual(got, test.want) {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
+		}
+	}
+}
+
+func TestUnaryExpGolombBinString(t *testing.T) {
+	tests := []struct {
+		v, uCoff, k   int
+		signedValFlag bool
+		want          []int
+	}{
+		0: {v: 7, uCoff: 14, want: []int{1, 1, 1, 1, 1, 1, 1, 0}},
+		1: {v: 17, uCoff: 14, want: []int{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0}},
+		2: {v: 15, uCoff: 14, signedValFlag: true, want: []int{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0}},
+		3: {v: -15, uCoff: 14, signedValFlag: true, want: []int{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1}},
+	}
+
+	for i, test := range tests {
+		got, err := unaryExpGolombBinString(test.v, test.uCoff, test.k, test.signedValFlag)
+		if err != nil {
+			t.Errorf("did not expect error %v for test %d", err, i)
+		}
+
+		if !reflect.DeepEqual(got, test.want) {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, got, test.want)
+		}
+	}
+}
diff --git a/codec/h264/h264dec/cavlc.go b/codec/h264/h264dec/cavlc.go
new file mode 100644
index 00000000..c477a490
--- /dev/null
+++ b/codec/h264/h264dec/cavlc.go
@@ -0,0 +1,46 @@
+/*
+DESCRIPTION
+  cavlc.go provides utilities for context-adaptive variable-length coding
+  for the parsing of H.264 syntax structure fields.
+
+AUTHORS
+  Saxon A. Nelson-Milton <saxon@ausocean.org>
+
+LICENSE
+  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
+  Free Software Foundation, either version 3 of the License, or (at your
+  option) any later version.
+
+  It is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+  for more details.
+
+  You should have received a copy of the GNU General Public License
+  in gpl.txt.  If not, see http://www.gnu.org/licenses.
+*/
+
+package h264dec
+
+import (
+	"fmt"
+
+	"bitbucket.org/ausocean/av/codec/h264/h264dec/bits"
+)
+
+// parseLevelPrefix parses the level_prefix variable as specified by the process
+// outlined in section 9.2.2.1 in the specifications.
+func parseLevelPrefix(br *bits.BitReader) (int, error) {
+	zeros := -1
+	for b := 0; b != 1; zeros++ {
+		_b, err := br.ReadBits(1)
+		if err != nil {
+			return -1, fmt.Errorf("could not read bit, failed with error: %v", err)
+		}
+		b = int(_b)
+	}
+	return zeros, nil
+}
diff --git a/codec/h264/h264dec/cavlc_test.go b/codec/h264/h264dec/cavlc_test.go
new file mode 100644
index 00000000..a6740858
--- /dev/null
+++ b/codec/h264/h264dec/cavlc_test.go
@@ -0,0 +1,55 @@
+/*
+DESCRIPTION
+  cavlc_test.go provides testing for functionality in cavlc.go.
+
+AUTHORS
+  Saxon A. Nelson-Milton <saxon@ausocean.org>
+
+LICENSE
+  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
+  Free Software Foundation, either version 3 of the License, or (at your
+  option) any later version.
+
+  It is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+  for more details.
+
+  You should have received a copy of the GNU General Public License
+  in gpl.txt.  If not, see http://www.gnu.org/licenses.
+*/
+
+package h264dec
+
+import (
+	"bytes"
+	"testing"
+
+	"bitbucket.org/ausocean/av/codec/h264/h264dec/bits"
+)
+
+func TestParseLevelPrefix(t *testing.T) {
+	tests := []struct {
+		in   string
+		want int
+	}{
+		{in: "00001", want: 4},
+		{in: "0000001", want: 6},
+		{in: "1", want: 0},
+	}
+
+	for i, test := range tests {
+		s, _ := binToSlice(test.in)
+		l, err := parseLevelPrefix(bits.NewBitReader(bytes.NewReader(s)))
+		if err != nil {
+			t.Errorf("did not expect error: %v, for test %d", err, i)
+		}
+
+		if l != test.want {
+			t.Errorf("did not get expected result for test %d\nGot: %d\nWant: %d\n", i, l, test.want)
+		}
+	}
+}
diff --git a/codec/h264/h264dec/frame.go b/codec/h264/h264dec/frame.go
index 82b32ae5..ca85982b 100644
--- a/codec/h264/h264dec/frame.go
+++ b/codec/h264/h264dec/frame.go
@@ -9,7 +9,7 @@ const (
 	naluTypeSlicePartC
 	naluTypeSliceIDRPicture
 	naluTypeSEI
-	naluTypeSPS
+	NALTypeSPS
 	naluTypePPS
 	naluTypeAccessUnitDelimiter
 	naluTypeEndOfSequence
diff --git a/codec/h264/h264dec/read.go b/codec/h264/h264dec/read.go
index c98d46ca..9b283c92 100644
--- a/codec/h264/h264dec/read.go
+++ b/codec/h264/h264dec/read.go
@@ -61,7 +61,7 @@ func (h *H264Reader) Start() {
 		// TODO: need to handle error from this.
 		nalUnit, _, _ := h.readNalUnit()
 		switch nalUnit.Type {
-		case naluTypeSPS:
+		case NALTypeSPS:
 			// TODO: handle this error
 			sps, _ := NewSPS(nalUnit.RBSP, false)
 			h.VideoStreams = append(
diff --git a/codec/h264/parse.go b/codec/h264/parse.go
new file mode 100644
index 00000000..9465fb1c
--- /dev/null
+++ b/codec/h264/parse.go
@@ -0,0 +1,71 @@
+/*
+DESCRIPTION
+  parse.go provides H.264 NAL unit parsing utilities for the extraction of
+	syntax elements.
+
+AUTHORS
+  Saxon A. Nelson-Milton <saxon@ausocean.org>
+  Dan Kortschak <dan@ausocean.org>
+
+LICENSE
+  Copyright (C) 2017-2018 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
+  Free Software Foundation, either version 3 of the License, or (at your
+  option) any later version.
+
+  It is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+  for more details.
+
+  You should have received a copy of the GNU General Public License
+  in gpl.txt.  If not, see http://www.gnu.org/licenses.
+*/
+
+package h264
+
+import "errors"
+
+var errNotEnoughBytes = errors.New("not enough bytes to read")
+
+// NALType returns the NAL type of the given NAL unit bytes. The given NAL unit
+// may be in byte stream or packet format.
+func NALType(n []byte) (int, error) {
+	sc := frameScanner{buf: n}
+	b, ok := sc.readByte()
+	if !ok {
+		return 0, errNotEnoughBytes
+	}
+	for i := 1; b == 0x00 && i != 4; i++ {
+		b, ok = sc.readByte()
+		if !ok {
+			return 0, errNotEnoughBytes
+		}
+		if b != 0x01 || (i != 2 && i != 3) {
+			continue
+		}
+
+		b, ok = sc.readByte()
+		if !ok {
+			return 0, errNotEnoughBytes
+		}
+		return int(b & 0x1f), nil
+	}
+	return int(b & 0x1f), nil
+}
+
+type frameScanner struct {
+	off int
+	buf []byte
+}
+
+func (s *frameScanner) readByte() (b byte, ok bool) {
+	if s.off >= len(s.buf) {
+		return 0, false
+	}
+	b = s.buf[s.off]
+	s.off++
+	return b, true
+}
diff --git a/container/mts/encoder.go b/container/mts/encoder.go
index 5d5533cb..7d968d5f 100644
--- a/container/mts/encoder.go
+++ b/container/mts/encoder.go
@@ -26,14 +26,53 @@ LICENSE
 package mts
 
 import (
+	"fmt"
 	"io"
+	"strconv"
 	"time"
 
+	"bitbucket.org/ausocean/av/codec/h264"
+	"bitbucket.org/ausocean/av/codec/h264/h264dec"
 	"bitbucket.org/ausocean/av/container/mts/meta"
 	"bitbucket.org/ausocean/av/container/mts/pes"
 	"bitbucket.org/ausocean/av/container/mts/psi"
+	"bitbucket.org/ausocean/utils/realtime"
 )
 
+// Media type values.
+// TODO: reference relevant specifications.
+const (
+	H264ID        = 27
+	H265ID        = 36
+	audioStreamID = 0xc0 // First audio stream ID.
+)
+
+// Constants used to communicate which media codec will be packetized.
+const (
+	EncodeH264 = iota
+	EncodeH265
+	EncodeAudio
+)
+
+// Time-related constants.
+const (
+	// ptsOffset is the offset added to the clock to determine
+	// the current presentation timestamp.
+	ptsOffset = 700 * time.Millisecond
+
+	// PCRFrequency is the base Program Clock Reference frequency in Hz.
+	PCRFrequency = 90000
+
+	// PTSFrequency is the presentation timestamp frequency in Hz.
+	PTSFrequency = 90000
+
+	// MaxPTS is the largest PTS value (i.e., for a 33-bit unsigned integer).
+	MaxPTS = (1 << 33) - 1
+)
+
+// If we are not using NAL based PSI intervals then we will send PSI every 7 packets.
+const psiSendCount = 7
+
 // Some common manifestations of PSI.
 var (
 	// StandardPAT is a minimal PAT.
@@ -72,51 +111,20 @@ var (
 	}
 )
 
-const (
-	psiInterval  = 1 * time.Second
-	psiSendCount = 7
-)
-
 // Meta allows addition of metadata to encoded mts from outside of this pkg.
 // See meta pkg for usage.
 //
 // TODO: make this not global.
 var Meta *meta.Data
 
+// This will help us obtain a realtime for timestamp meta encoding.
+var RealTime = realtime.NewRealTime()
+
 var (
 	patTable = StandardPAT.Bytes()
 	pmtTable []byte
 )
 
-const (
-	H264ID        = 27
-	H265ID        = 36
-	audioStreamID = 0xc0 // First audio stream ID.
-)
-
-// Constants used to communicate which media codec will be packetized.
-const (
-	EncodeH264 = iota
-	EncodeH265
-	EncodeAudio
-)
-
-// Time-related constants.
-const (
-	// ptsOffset is the offset added to the clock to determine
-	// the current presentation timestamp.
-	ptsOffset = 700 * time.Millisecond
-
-	// PCRFrequency is the base Program Clock Reference frequency in Hz.
-	PCRFrequency = 90000
-
-	// PTSFrequency is the presentation timestamp frequency in Hz.
-	PTSFrequency = 90000
-
-	// MaxPTS is the largest PTS value (i.e., for a 33-bit unsigned integer).
-	MaxPTS = (1 << 33) - 1
-)
-
 // Encoder encapsulates properties of an MPEG-TS generator.
 type Encoder struct {
 	dst io.WriteCloser
@@ -130,13 +138,11 @@ type Encoder struct {
 
 	continuity map[int]byte
 
-	timeBasedPsi bool
+	nalBasedPSI  bool
 	pktCount     int
 	psiSendCount int
 	mediaPid     int
 	streamID     byte
-
-	psiLastTime time.Time
 }
 
 // NewEncoder returns an Encoder with the specified media type and rate eg. if a video stream
@@ -174,7 +180,7 @@ func NewEncoder(dst io.WriteCloser, rate float64, mediaType int) *Encoder {
 		writePeriod: time.Duration(float64(time.Second) / rate),
 		ptsOffset:   ptsOffset,
 
-		timeBasedPsi: true,
+		nalBasedPSI: true,
 
 		pktCount: 8,
 
@@ -199,12 +205,8 @@ const (
 	hasPTS = 0x2
 )
 
-// TimeBasedPsi allows for the setting of the PSI writing method, therefore, if
-// PSI is written based on some time duration, or based on a packet count.
-// If b is true, then time based PSI is used, otherwise the PSI is written
-// every sendCount.
-func (e *Encoder) TimeBasedPsi(b bool, sendCount int) {
-	e.timeBasedPsi = b
+func (e *Encoder) NALBasedPSI(b bool, sendCount int) {
+	e.nalBasedPSI = b
 	e.psiSendCount = sendCount
 	e.pktCount = e.psiSendCount
 }
@@ -212,14 +214,24 @@ func (e *Encoder) TimeBasedPsi(b bool, sendCount int) {
 // Write implements io.Writer. Write takes raw video or audio data and encodes into MPEG-TS,
 // then sending it to the encoder's io.Writer destination.
 func (e *Encoder) Write(data []byte) (int, error) {
-	now := time.Now()
-	if (e.timeBasedPsi && (now.Sub(e.psiLastTime) > psiInterval)) || (!e.timeBasedPsi && (e.pktCount >= e.psiSendCount)) {
+	if e.nalBasedPSI {
+		nalType, err := h264.NALType(data)
+		if err != nil {
+			return 0, fmt.Errorf("could not get type from NAL unit, failed with error: %v", err)
+		}
+
+		if nalType == h264dec.NALTypeSPS {
+			err := e.writePSI()
+			if err != nil {
+				return 0, err
+			}
+		}
+	} else if e.pktCount >= e.psiSendCount {
 		e.pktCount = 0
 		err := e.writePSI()
 		if err != nil {
 			return 0, err
 		}
-		e.psiLastTime = now
 	}
 
 	// Prepare PES data.
@@ -328,6 +340,9 @@ func (e *Encoder) ccFor(pid int) byte {
 // contained in the global Meta struct.
 func updateMeta(b []byte) ([]byte, error) {
 	p := psi.PSIBytes(b)
+	if RealTime.IsSet() {
+		Meta.Add("ts", strconv.Itoa(int(RealTime.Get().Unix())))
+	}
 	err := p.AddDescriptor(psi.MetadataTag, Meta.Encode())
 	return []byte(p), err
 }
diff --git a/container/mts/mpegts.go b/container/mts/mpegts.go
index 8ca509ba..fe31b5ce 100644
--- a/container/mts/mpegts.go
+++ b/container/mts/mpegts.go
@@ -650,8 +650,11 @@ func SegmentForMeta(d []byte, key, val string) ([][]byte, error) {
 }
 
 // pid returns the packet identifier for the given packet.
-func pid(p []byte) uint16 {
-	return uint16(p[1]&0x1f)<<8 | uint16(p[2])
+func PID(p []byte) (uint16, error) {
+	if len(p) < PacketSize {
+		return 0, errors.New("packet length less than 188")
+	}
+	return uint16(p[1]&0x1f)<<8 | uint16(p[2]), nil
 }
 
 // Programs returns a map of program numbers and corresponding PMT PIDs for a
@@ -683,10 +686,14 @@ func Streams(p []byte) ([]gotspsi.PmtElementaryStream, error) {
 // but this program may contain different streams, i.e. a video stream + audio
 // stream.
 func MediaStreams(p []byte) ([]gotspsi.PmtElementaryStream, error) {
+	if len(p) < 2*PacketSize {
+		return nil, errors.New("PSI is not two packets or more long")
+	}
 	pat := p[:PacketSize]
 	pmt := p[PacketSize : 2*PacketSize]
 
-	if pid(pat) != PatPid {
+	pid, _ := PID(pat)
+	if pid != PatPid {
 		return nil, errors.New("first packet is not a PAT")
 	}
 
@@ -703,7 +710,8 @@ func MediaStreams(p []byte) ([]gotspsi.PmtElementaryStream, error) {
 		return nil, ErrMultiplePrograms
 	}
 
-	if pid(pmt) != pmtPIDs(m)[0] {
+	pid, _ = PID(pmt)
+	if pid != pmtPIDs(m)[0] {
 		return nil, errors.New("second packet is not desired PMT")
 	}
 
diff --git a/revid/config.go b/revid/config.go
index 42ab2b5d..87fb9139 100644
--- a/revid/config.go
+++ b/revid/config.go
@@ -27,6 +27,7 @@ package revid
 
 import (
 	"errors"
+	"time"
 
 	"bitbucket.org/ausocean/av/codec/codecutil"
 	"bitbucket.org/ausocean/utils/logger"
@@ -102,15 +103,16 @@ const (
 	defaultBurstPeriod = 10 // Seconds
 
 	// Raspivid video defaults.
-	defaultBrightness         = 50
-	defaultExposure           = "auto"
-	defaultAutoWhiteBalance   = "auto"
-	defaultRotation           = 0 // Degrees
-	defaultWidth              = 1280
-	defaultHeight             = 720
-	defaultIntraRefreshPeriod = 100
-	defaultQuantization       = 30
-	defaultBitrate            = 400000
+	defaultBrightness       = 50
+	defaultExposure         = "auto"
+	defaultAutoWhiteBalance = "auto"
+	defaultRotation         = 0 // Degrees
+	defaultWidth            = 1280
+	defaultHeight           = 720
+	defaultMinFrames        = 100
+	defaultClipDuration     = 0
+	defaultQuantization     = 30
+	defaultBitrate          = 400000
 
 	// Audio defaults.
 	defaultAudioInputCodec = codecutil.ADPCM
@@ -202,9 +204,16 @@ type Config struct {
 	// are using Raspivid input.
 	Quantization uint
 
-	// IntraRefreshPeriod defines the frequency of video parameter NAL units for
-	// Raspivid input.
-	IntraRefreshPeriod uint
+	// MinFrames defines the frequency of key NAL units SPS, PPS and IDR in
+	// number of NAL units. This will also determine the frequency of PSI if the
+	// output container is MPEG-TS. If ClipDuration is less than MinFrames,
+	// ClipDuration will default to MinFrames.
+	MinFrames uint
+
+	// ClipDuration is the duration of MTS data that is sent using HTTP or RTP
+	// output. This defaults to 0, therefore MinFrames will determine the length of
+	// clips by default.
+	ClipDuration time.Duration
 
 	// Logger holds an implementation of the Logger interface as defined in revid.go.
 	// This must be set for revid to work correctly.
@@ -383,9 +392,18 @@ func (c *Config) Validate() error {
 		return errors.New("invalid bitrate")
 	}
 
-	if c.IntraRefreshPeriod == 0 {
-		c.Logger.Log(logger.Info, pkg+"no intra refresh defined, defaulting", "intraRefresh", defaultIntraRefreshPeriod)
-		c.IntraRefreshPeriod = defaultIntraRefreshPeriod
+	if c.MinFrames == 0 {
+		c.Logger.Log(logger.Info, pkg+"no min period defined, defaulting", "MinFrames", defaultMinFrames)
+		c.MinFrames = defaultMinFrames
+	} else if c.MinFrames < 0 {
+		return errors.New("refresh period is less than 0")
+	}
+
+	if c.ClipDuration == 0 {
+		c.Logger.Log(logger.Info, pkg+"no clip duration defined, defaulting", "ClipDuration", defaultClipDuration)
+		c.ClipDuration = defaultClipDuration
+	} else if c.ClipDuration < 0 {
+		return errors.New("clip duration is less than 0")
 	}
 
 	if c.Quantization != 0 && (c.Quantization < 10 || c.Quantization > 40) {
diff --git a/revid/revid.go b/revid/revid.go
index 9e11844a..fa1156b1 100644
--- a/revid/revid.go
+++ b/revid/revid.go
@@ -51,6 +51,7 @@ import (
 	"bitbucket.org/ausocean/iot/pi/netsender"
 	"bitbucket.org/ausocean/utils/ioext"
 	"bitbucket.org/ausocean/utils/logger"
+	"bitbucket.org/ausocean/utils/ring"
 )
 
 // RTMP connection properties.
@@ -230,9 +231,8 @@ func (r *Revid) setupPipeline(mtsEnc func(dst io.WriteCloser, rate float64) (io.
 			w = newMtsSender(
 				newHttpSender(r.ns, r.config.Logger.Log),
 				r.config.Logger.Log,
-				r.config.MTSRBSize,
-				r.config.MTSRBElementSize,
-				0,
+				ring.NewBuffer(r.config.MTSRBSize, r.config.MTSRBElementSize, 0),
+				r.config.ClipDuration,
 			)
 			mtsSenders = append(mtsSenders, w)
 		case RTP:
@@ -456,13 +456,21 @@ func (r *Revid) Update(vars map[string]string) error {
 				break
 			}
 			r.config.Quantization = uint(v)
-		case "IntraRefreshPeriod":
-			p, err := strconv.ParseUint(value, 10, 0)
+		case "MinFrames":
+			v, err := strconv.Atoi(value)
 			if err != nil {
-				r.config.Logger.Log(logger.Warning, pkg+"invalid intrarefreshperiod param", "value", value)
+				r.config.Logger.Log(logger.Warning, pkg+"invalid MinFrames param", "value", value)
 				break
 			}
-			r.config.IntraRefreshPeriod = uint(p)
+			r.config.MinFrames = uint(v)
+
+		case "ClipDuration":
+			v, err := strconv.Atoi(value)
+			if err != nil {
+				r.config.Logger.Log(logger.Warning, pkg+"invalid ClipDuration param", "value", value)
+				break
+			}
+			r.config.ClipDuration = time.Duration(v) * time.Second
 
 		case "HorizontalFlip":
 			switch strings.ToLower(value) {
@@ -577,7 +585,7 @@ func (r *Revid) startRaspivid() (func() error, error) {
 		args = append(args,
 			"--codec", "H264",
 			"--inline",
-			"--intra", fmt.Sprint(r.config.IntraRefreshPeriod),
+			"--intra", fmt.Sprint(r.config.MinFrames),
 		)
 		if r.config.Quantization != 0 {
 			args = append(args, "-qp", fmt.Sprint(r.config.Quantization))
diff --git a/revid/senders.go b/revid/senders.go
index 303663ec..a6a593bd 100644
--- a/revid/senders.go
+++ b/revid/senders.go
@@ -29,11 +29,11 @@ LICENSE
 package revid
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net"
 	"os"
-	"strconv"
 	"sync"
 	"time"
 
@@ -118,7 +118,7 @@ func extractMeta(r string, log func(lvl int8, msg string, args ...interface{}))
 		log(logger.Warning, pkg+"No timestamp in reply")
 	} else {
 		log(logger.Debug, fmt.Sprintf("%v got timestamp: %v", pkg, t))
-		mts.Meta.Add("ts", strconv.Itoa(t))
+		mts.RealTime.Set(time.Unix(int64(t), 0))
 	}
 
 	// Extract location from reply
@@ -156,8 +156,8 @@ func (s *fileSender) Close() error { return s.file.Close() }
 
 // mtsSender implements io.WriteCloser and provides sending capability specifically
 // for use with MPEGTS packetization. It handles the construction of appropriately
-// lengthed clips based on PSI. It also accounts for discontinuities by
-// setting the discontinuity indicator for the first packet of a clip.
+// lengthed clips based on clip duration and PSI. It also accounts for
+// discontinuities by setting the discontinuity indicator for the first packet of a clip.
 type mtsSender struct {
 	dst      io.WriteCloser
 	buf      []byte
@@ -166,19 +166,22 @@ type mtsSender struct {
 	pkt      packet.Packet
 	repairer *mts.DiscontinuityRepairer
 	curPid   int
+	clipDur  time.Duration
+	prev     time.Time
 	done     chan struct{}
 	log      func(lvl int8, msg string, args ...interface{})
 	wg       sync.WaitGroup
 }
 
 // newMtsSender returns a new mtsSender.
-func newMtsSender(dst io.WriteCloser, log func(lvl int8, msg string, args ...interface{}), ringSize int, ringElementSize int, wTimeout time.Duration) *mtsSender {
+func newMtsSender(dst io.WriteCloser, log func(lvl int8, msg string, args ...interface{}), rb *ring.Buffer, clipDur time.Duration) *mtsSender {
 	s := &mtsSender{
 		dst:      dst,
 		repairer: mts.NewDiscontinuityRepairer(),
 		log:      log,
-		ring:     ring.NewBuffer(ringSize, ringElementSize, wTimeout),
+		ring:     rb,
 		done:     make(chan struct{}),
+		clipDur:  clipDur,
 	}
 	s.wg.Add(1)
 	go s.output()
@@ -229,15 +232,20 @@ func (s *mtsSender) output() {
 
 // Write implements io.Writer.
 func (s *mtsSender) Write(d []byte) (int, error) {
+	if len(d) < mts.PacketSize {
+		return 0, errors.New("do not have full MTS packet")
+	}
+
 	if s.next != nil {
 		s.buf = append(s.buf, s.next...)
 	}
 	bytes := make([]byte, len(d))
 	copy(bytes, d)
 	s.next = bytes
-	copy(s.pkt[:], bytes)
-	s.curPid = s.pkt.PID()
-	if s.curPid == mts.PatPid && len(s.buf) > 0 {
+	p, _ := mts.PID(bytes)
+	s.curPid = int(p)
+	if time.Now().Sub(s.prev) >= s.clipDur && s.curPid == mts.PatPid && len(s.buf) > 0 {
+		s.prev = time.Now()
 		_, err := s.ring.Write(s.buf)
 		if err != nil {
 			s.log(logger.Warning, pkg+"mtsSender: ringBuffer write error", "error", err.Error())
diff --git a/revid/senders_test.go b/revid/senders_test.go
index d92f19f4..3fe2f291 100644
--- a/revid/senders_test.go
+++ b/revid/senders_test.go
@@ -39,6 +39,7 @@ import (
 	"bitbucket.org/ausocean/av/container/mts"
 	"bitbucket.org/ausocean/av/container/mts/meta"
 	"bitbucket.org/ausocean/utils/logger"
+	"bitbucket.org/ausocean/utils/ring"
 )
 
 var (
@@ -133,12 +134,12 @@ func TestMtsSenderSegment(t *testing.T) {
 	// Create ringBuffer, sender, sender and the MPEGTS encoder.
 	const numberOfClips = 11
 	dst := &destination{t: t, done: make(chan struct{}), doneAt: numberOfClips}
-	sender := newMtsSender(dst, (*dummyLogger)(t).log, defaultMTSRBSize, defaultMTSRBElementSize, 0)
+	sender := newMtsSender(dst, (*dummyLogger)(t).log, ring.NewBuffer(defaultMTSRBSize, defaultMTSRBElementSize, 0), 0)
 	encoder := mts.NewEncoder(sender, 25, mts.EncodeH264)
 
 	// Turn time based PSI writing off for encoder.
 	const psiSendCount = 10
-	encoder.TimeBasedPsi(false, psiSendCount)
+	encoder.NALBasedPSI(false, psiSendCount)
 
 	// Write the packets to the encoder, which will in turn write to the mtsSender.
 	// Payload will just be packet number.
@@ -211,12 +212,12 @@ func TestMtsSenderFailedSend(t *testing.T) {
 	// Create destination, the mtsSender and the mtsEncoder
 	const clipToFailAt = 3
 	dst := &destination{t: t, testFails: true, failAt: clipToFailAt, done: make(chan struct{})}
-	sender := newMtsSender(dst, (*dummyLogger)(t).log, defaultMTSRBSize, defaultMTSRBElementSize, 0)
+	sender := newMtsSender(dst, (*dummyLogger)(t).log, ring.NewBuffer(defaultMTSRBSize, defaultMTSRBElementSize, 0), 0)
 	encoder := mts.NewEncoder(sender, 25, mts.EncodeH264)
 
 	// Turn time based PSI writing off for encoder and send PSI every 10 packets.
 	const psiSendCount = 10
-	encoder.TimeBasedPsi(false, psiSendCount)
+	encoder.NALBasedPSI(false, psiSendCount)
 
 	// Write the packets to the encoder, which will in turn write to the mtsSender.
 	// Payload will just be packet number.
@@ -291,12 +292,12 @@ func TestMtsSenderDiscontinuity(t *testing.T) {
 	// Create destination, the mtsSender and the mtsEncoder.
 	const clipToDelay = 3
 	dst := &destination{t: t, sendDelay: 10 * time.Millisecond, delayAt: clipToDelay, done: make(chan struct{})}
-	sender := newMtsSender(dst, (*dummyLogger)(t).log, 1, defaultMTSRBElementSize, 0)
+	sender := newMtsSender(dst, (*dummyLogger)(t).log, ring.NewBuffer(1, defaultMTSRBElementSize, 0), 0)
 	encoder := mts.NewEncoder(sender, 25, mts.EncodeH264)
 
 	// Turn time based PSI writing off for encoder.
 	const psiSendCount = 10
-	encoder.TimeBasedPsi(false, psiSendCount)
+	encoder.NALBasedPSI(false, psiSendCount)
 
 	// Write the packets to the encoder, which will in turn write to the mtsSender.
 	// Payload will just be packet number.