H265 reader & writer

H265 raeder & writer

Author: cnderrauber

pkg/media/h265reader/h265reader.go

@@ -0,0 +1,232 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+// Package h265reader implements a H265/HEVC Annex-B Reader
+package h265reader
+
+import (
+	"bytes"
+	"errors"
+	"io"
+)
+
+// H265Reader reads data from stream and constructs h265 nal units.
+type H265Reader struct {
+	stream                      io.Reader
+	nalBuffer                   []byte
+	countOfConsecutiveZeroBytes int
+	nalPrefixParsed             bool
+	readBuffer                  []byte
+	tmpReadBuf                  []byte
+}
+
+var (
+	errNilReader           = errors.New("stream is nil")
+	errDataIsNotH265Stream = errors.New("data is not a H265/HEVC bitstream")
+)
+
+// NewReader creates new H265Reader.
+func NewReader(in io.Reader) (*H265Reader, error) {
+	if in == nil {
+		return nil, errNilReader
+	}
+
+	reader := &H265Reader{
+		stream:          in,
+		nalBuffer:       make([]byte, 0),
+		nalPrefixParsed: false,
+		readBuffer:      make([]byte, 0),
+		tmpReadBuf:      make([]byte, 4096),
+	}
+
+	return reader, nil
+}
+
+// NAL H.265/HEVC Network Abstraction Layer.
+type NAL struct {
+	PictureOrderCount uint32
+
+	/* NAL Unit header https://datatracker.ietf.org/doc/html/rfc7798#section-1.1.4
+	+---------------+---------------+
+	|0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7|
+	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	|F|   Type    |  LayerId  | TID |
+	+-------------+-----------------+
+	*/
+	ForbiddenZeroBit bool
+	NalUnitType      NalUnitType
+	LayerID          uint8
+	TemporalIDPlus1  uint8
+
+	Data []byte // header bytes + rbsp
+}
+
+func (reader *H265Reader) read(numToRead int) (data []byte, e error) {
+	for len(reader.readBuffer) < numToRead {
+		n, err := reader.stream.Read(reader.tmpReadBuf)
+		if err != nil {
+			return nil, err
+		}
+		if n == 0 {
+			break
+		}
+		reader.readBuffer = append(reader.readBuffer, reader.tmpReadBuf[0:n]...)
+	}
+	var numShouldRead int
+	if numToRead <= len(reader.readBuffer) {
+		numShouldRead = numToRead
+	} else {
+		numShouldRead = len(reader.readBuffer)
+	}
+	data = reader.readBuffer[0:numShouldRead]
+	reader.readBuffer = reader.readBuffer[numShouldRead:]
+
+	return data, nil
+}
+
+func (reader *H265Reader) bitStreamStartsWithH265Prefix() (prefixLength int, e error) {
+	nalPrefix3Bytes := []byte{0, 0, 1}
+	nalPrefix4Bytes := []byte{0, 0, 0, 1}
+
+	prefixBuffer, e := reader.read(4)
+	if e != nil {
+		return prefixLength, e
+	}
+
+	n := len(prefixBuffer)
+
+	if n == 0 {
+		return 0, io.EOF
+	}
+
+	if n < 3 {
+		return 0, errDataIsNotH265Stream
+	}
+
+	nalPrefix3BytesFound := bytes.Equal(nalPrefix3Bytes, prefixBuffer[:3])
+	if n == 3 {
+		if nalPrefix3BytesFound {
+			return 0, io.EOF
+		}
+
+		return 0, errDataIsNotH265Stream
+	}
+
+	// n == 4
+	if nalPrefix3BytesFound {
+		reader.nalBuffer = append(reader.nalBuffer, prefixBuffer[3])
+
+		return 3, nil
+	}
+
+	nalPrefix4BytesFound := bytes.Equal(nalPrefix4Bytes, prefixBuffer)
+	if nalPrefix4BytesFound {
+		return 4, nil
+	}
+
+	return 0, errDataIsNotH265Stream
+}
+
+// NextNAL reads from stream and returns then next NAL,
+// and an error if there is incomplete frame data.
+// Returns all nil values when no more NALs are available.
+func (reader *H265Reader) NextNAL() (*NAL, error) {
+	if !reader.nalPrefixParsed {
+		_, err := reader.bitStreamStartsWithH265Prefix()
+		if err != nil {
+			return nil, err
+		}
+
+		reader.nalPrefixParsed = true
+	}
+
+	for {
+		buffer, err := reader.read(1)
+		if err != nil {
+			break
+		}
+
+		n := len(buffer)
+
+		if n != 1 {
+			break
+		}
+		readByte := buffer[0]
+		nalFound := reader.processByte(readByte)
+		if nalFound {
+			naluType := NalUnitType((reader.nalBuffer[0] & 0x7E) >> 1)
+			if naluType == NalUnitTypePrefixSei || naluType == NalUnitTypeSuffixSei {
+				reader.nalBuffer = nil
+
+				continue
+			}
+
+			break
+		}
+
+		reader.nalBuffer = append(reader.nalBuffer, readByte)
+	}
+
+	if len(reader.nalBuffer) == 0 {
+		return nil, io.EOF
+	}
+
+	nal := newNal(reader.nalBuffer)
+	reader.nalBuffer = nil
+	nal.parseHeader()
+
+	return nal, nil
+}
+
+func (reader *H265Reader) processByte(readByte byte) (nalFound bool) {
+	nalFound = false
+
+	switch readByte {
+	case 0:
+		reader.countOfConsecutiveZeroBytes++
+	case 1:
+		if reader.countOfConsecutiveZeroBytes >= 2 {
+			countOfConsecutiveZeroBytesInPrefix := 2
+			if reader.countOfConsecutiveZeroBytes > 2 {
+				countOfConsecutiveZeroBytesInPrefix = 3
+			}
+
+			if nalUnitLength := len(reader.nalBuffer) - countOfConsecutiveZeroBytesInPrefix; nalUnitLength > 0 {
+				reader.nalBuffer = reader.nalBuffer[0:nalUnitLength]
+				nalFound = true
+			}
+		}
+
+		reader.countOfConsecutiveZeroBytes = 0
+	default:
+		reader.countOfConsecutiveZeroBytes = 0
+	}
+
+	return nalFound
+}
+
+func newNal(data []byte) *NAL {
+	return &NAL{
+		PictureOrderCount: 0,
+		ForbiddenZeroBit:  false,
+		NalUnitType:       NalUnitTypeTrailN,
+		LayerID:           0,
+		TemporalIDPlus1:   0,
+		Data:              data,
+	}
+}
+
+func (h *NAL) parseHeader() {
+	if len(h.Data) < 2 {
+		return
+	}
+
+	// H.265 NAL header is 2 bytes
+	firstByte := h.Data[0]
+	secondByte := h.Data[1]
+
+	h.ForbiddenZeroBit = (firstByte & 0x80) != 0
+	h.NalUnitType = NalUnitType((firstByte & 0x7E) >> 1)
+	h.LayerID = ((firstByte & 0x01) << 5) | ((secondByte & 0xF8) >> 3)
+	h.TemporalIDPlus1 = secondByte & 0x07
+}

pkg/media/h265reader/h265reader_test.go

@@ -0,0 +1,123 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package h265reader
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestH265Reader_NextNAL(t *testing.T) {
+	// Test with invalid data
+	reader, err := NewReader(bytes.NewReader([]byte{0xFF, 0xFF, 0xFF, 0xFF}))
+	assert.NoError(t, err)
+
+	_, err = reader.NextNAL()
+	assert.Equal(t, errDataIsNotH265Stream.Error(), err.Error())
+
+	// Test with valid H265 prefix but no NAL data
+	reader, err = NewReader(bytes.NewReader([]byte{0, 0, 1}))
+	assert.NoError(t, err)
+
+	_, err = reader.NextNAL()
+	assert.Equal(t, io.EOF, err)
+
+	// Test with valid H265 NAL unit (VPS example)
+	nalData := []byte{
+		0x0, 0x0, 0x0, 0x1, 0x40, 0x01, 0x0C, 0x01, 0xFF, 0xFF, 0x01, 0x60, 0x00,
+		0x00, 0x03, 0x00, 0x90, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x78, 0xAC, 0x09,
+	}
+	reader, err = NewReader(bytes.NewReader(nalData))
+	assert.NoError(t, err)
+
+	nal, err := reader.NextNAL()
+	assert.NoError(t, err)
+	assert.NotNil(t, nal)
+
+	assert.Equal(t, NalUnitTypeVps, nal.NalUnitType)
+	assert.False(t, nal.ForbiddenZeroBit)
+
+	// Test reading multiple NAL units
+	nalData = append(nalData, []byte{
+		0x0, 0x0, 0x0, 0x1, 0x42, 0x01, 0x01, 0x01, 0x60, 0x00, 0x00, 0x03,
+		0x00, 0x90, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x78, 0xA0,
+		0x03, 0xC0, 0x80, 0x10, 0xE5, 0x96, 0x56, 0x69, 0x24, 0xCA, 0xE0,
+		0x10, 0x00, 0x00, 0x03, 0x00, 0x10, 0x00, 0x00, 0x03, 0x01, 0xE0, 0x80,
+	}...)
+	reader, err = NewReader(bytes.NewReader(nalData))
+	assert.NoError(t, err)
+
+	// First NAL (VPS)
+	nal1, err := reader.NextNAL()
+	assert.NoError(t, err)
+	assert.Equal(t, NalUnitTypeVps, nal1.NalUnitType)
+
+	// Second NAL (SPS)
+	nal2, err := reader.NextNAL()
+	assert.NoError(t, err)
+	assert.Equal(t, NalUnitTypeSps, nal2.NalUnitType)
+
+	// Test EOF
+	_, err = reader.NextNAL()
+	assert.Equal(t, io.EOF, err)
+}
+
+func TestH265Reader_processByte(t *testing.T) {
+	reader := &H265Reader{
+		nalBuffer:                   []byte{1, 2, 3, 0, 0},
+		countOfConsecutiveZeroBytes: 2,
+	}
+
+	// Test finding NAL boundary
+	nalFound := reader.processByte(1)
+	assert.True(t, nalFound)
+	assert.Equal(t, 3, len(reader.nalBuffer))
+
+	// Test zero byte counting
+	reader.countOfConsecutiveZeroBytes = 0
+	nalFound = reader.processByte(0)
+	assert.False(t, nalFound)
+	assert.Equal(t, 1, reader.countOfConsecutiveZeroBytes)
+
+	// Test non-zero, non-one byte
+	reader.countOfConsecutiveZeroBytes = 5
+	nalFound = reader.processByte(0xFF)
+	assert.False(t, nalFound)
+	assert.Equal(t, 0, reader.countOfConsecutiveZeroBytes)
+}
+
+func TestNAL_parseHeader(t *testing.T) {
+	// Test VPS NAL header parsing
+	data := []byte{0x40, 0x01, 0x0C, 0x01} // VPS NAL unit
+	nal := newNal(data)
+	nal.parseHeader()
+
+	assert.False(t, nal.ForbiddenZeroBit)
+	assert.Equal(t, NalUnitTypeVps, nal.NalUnitType)
+	assert.Equal(t, uint8(0), nal.LayerID)
+	assert.Equal(t, uint8(1), nal.TemporalIDPlus1)
+
+	// Test SPS NAL header parsing
+	data = []byte{0x42, 0x01, 0x01, 0x01} // SPS NAL unit
+	nal = newNal(data)
+	nal.parseHeader()
+
+	assert.False(t, nal.ForbiddenZeroBit)
+	assert.Equal(t, NalUnitTypeSps, nal.NalUnitType)
+
+	// Test with insufficient data
+	data = []byte{0x40} // Only one byte
+	nal = newNal(data)
+	nal.parseHeader() // Should not panic
+
+	// Test forbidden bit set
+	data = []byte{0x80, 0x01} // Forbidden bit set
+	nal = newNal(data)
+	nal.parseHeader()
+
+	assert.True(t, nal.ForbiddenZeroBit)
+}