avc

package
v0.47.0 Latest Latest
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 Go to latest Published: Nov 12, 2024 License: MIT Imports: 10 Imported by: 4

Documentation

Overview

Package avc parses AVC (H.264) NAL unit headers, slice headers and complete SPS and PPS.

Index

Constants

View Source 
const (
	// NALU_NON_IDR - Non-IDR Slice NAL unit
	NALU_NON_IDR = NaluType(1)
	// NALU_IDR - IDR Random Access Slice NAL Unit
	NALU_IDR = NaluType(5)
	// NALU_SEI - Supplementary Enhancement Information NAL Unit
	NALU_SEI = NaluType(6)
	// NALU_SPS - SequenceParameterSet NAL Unit
	NALU_SPS = NaluType(7)
	// NALU_PPS - PictureParameterSet NAL Unit
	NALU_PPS = NaluType(8)
	// NALU_AUD - AccessUnitDelimiter NAL Unit
	NALU_AUD = NaluType(9)
	// NALU_EO_SEQ - End of Sequence NAL Unit
	NALU_EO_SEQ = NaluType(10)
	// NALU_EO_STREAM - End of Stream NAL Unit
	NALU_EO_STREAM = NaluType(11)
	// NALU_FILL - Filler NAL Unit
	NALU_FILL = NaluType(12)
)
View Source 
const (
	SLICE_P  = SliceType(0)
	SLICE_B  = SliceType(1)
	SLICE_I  = SliceType(2)
	SLICE_SP = SliceType(3)
	SLICE_SI = SliceType(4)
)

AVC slice types

View Source 
const ExtendedSAR = 255

ExtendedSAR - Extended Sample Aspect Ratio Code

Variables

View Source 
var (
	ErrCannotParseAVCExtension = errors.New("Cannot parse SPS extensions")
	ErrLengthSize              = errors.New("Can only handle 4byte NAL length size")
)

AVC parsing errors

View Source 
var (
	ErrNoSliceHeader      = errors.New("No slice header")
	ErrInvalidSliceType   = errors.New("Invalid slice type")
	ErrTooFewBytesToParse = errors.New("Too few bytes to parse symbol")
)

Errors for parsing and handling AVC slices

View Source 
var (
	ErrNotPPS = errors.New("Not an PPS NAL unit")
)

AVC PPS errors

View Source 
var (
	ErrNotSEINalu = errors.New("not an SEI NAL unit")
)
View Source 
var (
	ErrNotSPS = errors.New("Not an SPS NAL unit")
)

SPS errors

Functions

func CodecString 

func CodecString(sampleEntry string, sps *SPS) string

CodecString - sub-parameter for MIME type "codecs" parameter like avc1.42E00C where avc1 is sampleEntry. Defined in ISO/IEC 14496-15 2017.

func ContainsNaluType 

func ContainsNaluType(sample []byte, specificNalType NaluType) bool

ContainsNaluType - is specific NaluType present in sample

func ConvertByteStreamToNaluSample 

func ConvertByteStreamToNaluSample(stream []byte) []byte

ConvertByteStreamToNaluSample changes start codes to 4-byte length fields. This function is codec agnostic.

func ConvertSampleToByteStream 

func ConvertSampleToByteStream(sample []byte) []byte

ConvertSampleToByteStream replaces 4-byte NALU lengths with start codes. This function is codec agnostic.

func ExtractNalusFromByteStream 

func ExtractNalusFromByteStream(data []byte) [][]byte

ExtractNalusFromByteStream extracts NALUs without startcode from ByteStream. This function is codec agnostic.

func ExtractNalusOfTypeFromByteStream 

func ExtractNalusOfTypeFromByteStream(nType NaluType, data []byte, stopAtVideo bool) [][]byte

ExtractNalusOfTypeFromByteStream returns all AVC nalus of wanted type from bytestream. If stopAtVideo, the stream is not scanned beyond the first video NAL unit.

func GetFirstAVCVideoNALUFromByteStream 

func GetFirstAVCVideoNALUFromByteStream(data []byte) []byte

GetFirstAVCVideoNALUFromByteStream returns a slice with the first video nal unit. No new memory is allocated, but a subslice of data is returned.

func GetNalusFromSample 

func GetNalusFromSample(sample []byte) ([][]byte, error)

GetNalusFromSample - get nalus by following 4 byte length fields

func GetParameterSets 

func GetParameterSets(sample []byte) (sps [][]byte, pps [][]byte)

GetParameterSets - get (multiple) SPS and PPS from a sample

func GetParameterSetsFromByteStream 

func GetParameterSetsFromByteStream(data []byte) (spss, ppss [][]byte)

GetParameterSetsFromByteStream copies AVC SPS and PPS nalus from bytestream (Annex B)

func GetSARfromIDC 

func GetSARfromIDC(index uint) (uint, uint, error)

GetSARfromIDC - get Sample Aspect Ratio from IDC index

func HasParameterSets 

func HasParameterSets(b []byte) bool

HasParameterSets - Check if H.264 SPS and PPS are present

func IsIDRSample 

func IsIDRSample(sample []byte) bool

IsIDRSample - does sample contain IDR NALU

func IsVideoNaluType 

func IsVideoNaluType(naluType NaluType) bool

IsVideoNaluType returns true if nalu type is a VCL nalu.

func ParseSEINalu added in v0.36.0 

func ParseSEINalu(nalu []byte, sps *SPS) ([]sei.SEIMessage, error)

ParseSEINalu - parse SEI NAL unit (incl header) and return messages given SPS. Returns sei.ErrRbspTrailingBitsMissing if the NALU is missing the trailing bits.

Types

type CpbEntry 

type CpbEntry struct {
	BitRateValueMinus1 uint
	CpbSizeValueMinus1 uint
	CbrFlag            bool
}

CpbEntry inside HrdParameters

type DecConfRec 

type DecConfRec struct {
	AVCProfileIndication byte
	ProfileCompatibility byte
	AVCLevelIndication   byte
	SPSnalus             [][]byte
	PPSnalus             [][]byte
	ChromaFormat         byte
	BitDepthLumaMinus1   byte
	BitDepthChromaMinus1 byte
	NumSPSExt            byte
	NoTrailingInfo       bool // To handle strange cases where trailing info is missing
}

DecConfRec - AVCDecoderConfigurationRecord

func CreateAVCDecConfRec 

func CreateAVCDecConfRec(spsNalus [][]byte, ppsNalus [][]byte, includePS bool) (*DecConfRec, error)

CreateAVCDecConfRec - extract information from sps and insert sps, pps if includePS set

func DecodeAVCDecConfRec 

func DecodeAVCDecConfRec(data []byte) (DecConfRec, error)

DecodeAVCDecConfRec - decode an AVCDecConfRec

func (*DecConfRec) Encode 

func (a *DecConfRec) Encode(w io.Writer) error

Encode - write box to w

func (*DecConfRec) EncodeSW 

func (a *DecConfRec) EncodeSW(sw bits.SliceWriter) error

Encode - write an AVCDecConfRec to w

func (*DecConfRec) Size 

func (a *DecConfRec) Size() uint64

Size - total size in bytes

type HrdParameters 

type HrdParameters struct {
	CpbCountMinus1                     uint
	BitRateScale                       uint
	CpbSizeScale                       uint
	CpbEntries                         []CpbEntry
	InitialCpbRemovalDelayLengthMinus1 uint
	CpbRemovalDelayLengthMinus1        uint
	DpbOutputDelayLengthMinus1         uint
	TimeOffsetLength                   uint
}

HrdParameters inside VUI

type NaluType 

type NaluType uint16

NaluType - AVC NAL unit type

func FindNaluTypes 

func FindNaluTypes(sample []byte) []NaluType

FindNaluTypes - find list of NAL unit types in sample

func FindNaluTypesUpToFirstVideoNALU 

func FindNaluTypesUpToFirstVideoNALU(sample []byte) []NaluType

FindNaluTypesUpToFirstVideoNALU - find list of NAL unit types in sample

func GetNaluType 

func GetNaluType(naluHeader byte) NaluType

GetNaluType - get NALU type from NALU Header byte

func (NaluType) String 

func (a NaluType) String() string

type PPS 

type PPS struct {
	PicParameterSetID                     uint32
	SeqParameterSetID                     uint32
	EntropyCodingModeFlag                 bool
	BottomFieldPicOrderInFramePresentFlag bool
	NumSliceGroupsMinus1                  uint
	SliceGroupMapType                     uint
	RunLengthMinus1                       []uint
	TopLeft                               []uint
	BottomRight                           []uint
	SliceGroupChangeDirectionFlag         bool
	SliceGroupChangeRateMinus1            uint
	PicSizeInMapUnitsMinus1               uint
	SliceGroupID                          []uint
	NumRefIdxI0DefaultActiveMinus1        uint
	NumRefIdxI1DefaultActiveMinus1        uint
	WeightedPredFlag                      bool
	WeightedBipredIDC                     uint
	PicInitQpMinus26                      int
	PicInitQsMinus26                      int
	ChromaQpIndexOffset                   int
	DeblockingFilterControlPresentFlag    bool
	ConstrainedIntraPredFlag              bool
	RedundantPicCntPresentFlag            bool
	Transform8x8ModeFlag                  bool
	PicScalingMatrixPresentFlag           bool
	PicScalingLists                       []ScalingList
	SecondChromaQpIndexOffset             int
}

PPS - Picture Parameter Set

func ParsePPSNALUnit 

func ParsePPSNALUnit(data []byte, spsMap map[uint32]*SPS) (*PPS, error)

ParsePPSNALUnit - Parse AVC PPS NAL unit starting with NAL header

type SPS 

type SPS struct {
	Profile                         uint32
	ProfileCompatibility            uint32
	Level                           uint32
	ParameterID                     uint32
	ChromaFormatIDC                 byte
	SeparateColourPlaneFlag         bool
	BitDepthLumaMinus8              uint
	BitDepthChromaMinus8            uint
	QPPrimeYZeroTransformBypassFlag bool
	SeqScalingMatrixPresentFlag     bool
	SeqScalingLists                 []ScalingList
	Log2MaxFrameNumMinus4           uint
	PicOrderCntType                 uint
	Log2MaxPicOrderCntLsbMinus4     uint
	DeltaPicOrderAlwaysZeroFlag     bool
	OffsetForNonRefPic              uint
	OffsetForTopToBottomField       uint
	RefFramesInPicOrderCntCycle     []uint
	NumRefFrames                    uint
	GapsInFrameNumValueAllowedFlag  bool
	FrameMbsOnlyFlag                bool
	MbAdaptiveFrameFieldFlag        bool
	Direct8x8InferenceFlag          bool
	FrameCroppingFlag               bool
	FrameCropLeftOffset             uint
	FrameCropRightOffset            uint
	FrameCropTopOffset              uint
	FrameCropBottomOffset           uint
	Width                           uint
	Height                          uint
	NrBytesBeforeVUI                int
	NrBytesRead                     int
	VUI                             *VUIParameters
}

SPS - AVC SPS parameters

func ParseSPSNALUnit 

func ParseSPSNALUnit(data []byte, parseVUIBeyondAspectRatio bool) (*SPS, error)

ParseSPSNALUnit - Parse AVC SPS NAL unit starting with NAL header

func (*SPS) ChromaArrayType 

func (s *SPS) ChromaArrayType() byte

ChromaArrayType as defined in Section 7.4.2.1.1 under separate_colour_plane_flag

func (*SPS) ConstraintFlags 

func (a *SPS) ConstraintFlags() byte

ConstraintFlags - return the four ConstraintFlag bits

func (*SPS) CpbDpbDelaysPresent 

func (s *SPS) CpbDpbDelaysPresent() bool

CpbDbpDelaysPresent signals if Cpb and Dbp can be found in Picture Timing SEI

func (*SPS) PicStructPresent 

func (s *SPS) PicStructPresent() bool

PicStructPresent signals if pic struct can be found in Picture Timing SEI

type ScalingList 

type ScalingList []int

ScalingList - 4x4 or 8x8 Scaling lists. Nil if not present

type SliceHeader 

type SliceHeader struct {
	SliceType                     SliceType
	FirstMBInSlice                uint32
	PicParamID                    uint32
	SeqParamID                    uint32
	ColorPlaneID                  uint32
	FrameNum                      uint32
	IDRPicID                      uint32
	PicOrderCntLsb                uint32
	DeltaPicOrderCntBottom        int32
	DeltaPicOrderCnt              [2]int32
	RedundantPicCnt               uint32
	NumRefIdxL0ActiveMinus1       uint32
	NumRefIdxL1ActiveMinus1       uint32
	ModificationOfPicNumsIDC      uint32
	AbsDiffPicNumMinus1           uint32
	LongTermPicNum                uint32
	AbsDiffViewIdxMinus1          uint32
	LumaLog2WeightDenom           uint32
	ChromaLog2WeightDenom         uint32
	DifferenceOfPicNumsMinus1     uint32
	LongTermFramIdx               uint32
	MaxLongTermFrameIdxPlus1      uint32
	CabacInitIDC                  uint32
	SliceQPDelta                  int32
	SliceQSDelta                  int32
	DisableDeblockingFilterIDC    uint32
	SliceAlphaC0OffsetDiv2        int32
	SliceBetaOffsetDiv2           int32
	SliceGroupChangeCycle         uint32
	Size                          uint32
	FieldPicFlag                  bool
	BottomFieldFlag               bool
	DirectSpatialMvPredFlag       bool
	NumRefIdxActiveOverrideFlag   bool
	RefPicListModificationL0Flag  bool
	RefPicListModificationL1Flag  bool
	NoOutputOfPriorPicsFlag       bool
	LongTermReferenceFlag         bool
	SPForSwitchFlag               bool
	AdaptiveRefPicMarkingModeFlag bool
}

func ParseSliceHeader 

func ParseSliceHeader(nalu []byte, spsMap map[uint32]*SPS, ppsMap map[uint32]*PPS) (*SliceHeader, error)

ParseSliceHeader parses AVC slice header following the syntax in ISO/IEC 14496-10 section 7.3.3

type SliceType 

type SliceType uint

SliceType - AVC slice type

func GetSliceTypeFromNALU 

func GetSliceTypeFromNALU(data []byte) (sliceType SliceType, err error)

GetSliceTypeFromNALU - parse slice header to get slice type in interval 0 to 4

func (SliceType) String 

func (s SliceType) String() string

type VUIParameters 

type VUIParameters struct {
	SampleAspectRatioWidth             uint
	SampleAspectRatioHeight            uint
	OverscanInfoPresentFlag            bool
	OverscanAppropriateFlag            bool
	VideoSignalTypePresentFlag         bool
	VideoFormat                        uint
	VideoFullRangeFlag                 bool
	ColourDescriptionFlag              bool
	ColourPrimaries                    uint
	TransferCharacteristics            uint
	MatrixCoefficients                 uint
	ChromaLocInfoPresentFlag           bool
	ChromaSampleLocTypeTopField        uint
	ChromaSampleLocTypeBottomField     uint
	TimingInfoPresentFlag              bool
	NumUnitsInTick                     uint
	TimeScale                          uint
	FixedFrameRateFlag                 bool
	NalHrdParametersPresentFlag        bool
	NalHrdParameters                   *HrdParameters
	VclHrdParametersPresentFlag        bool
	VclHrdParameters                   *HrdParameters
	LowDelayHrdFlag                    bool // Only present with HrdParameters
	PicStructPresentFlag               bool
	BitstreamRestrictionFlag           bool
	MotionVectorsOverPicBoundariesFlag bool
	MaxBytesPerPicDenom                uint
	MaxBitsPerMbDenom                  uint
	Log2MaxMvLengthHorizontal          uint
	Log2MaxMvLengthVertical            uint
	MaxNumReorderFrames                uint
	MaxDecFrameBuffering               uint
}

VUIParameters - extra parameters according to 14496-10, E.1

Source Files

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