bits

package
v0.41.0 Latest Latest
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 Go to latest Published: Jan 12, 2024 License: MIT, MIT Imports: 5 Imported by: 6

Documentation

Overview

Package bits - bit reading and writing including Golomb codes and EBSP.

Beyond plain bit reading and writing, reading of ebsp (Encapsulated Byte Sequence Packets) Golomb codes as used in the AVC/H.264 and HEVC video coding standards.

Index

Constants

This section is empty.

Variables

View Source 
var (
	ErrNotReedSeeker = errors.New("Reader does not support Seek")
)

ESBPReader errors

View Source 
var (
	ErrSliceRead = fmt.Errorf("read too far in SliceReader")
)

SliceReader errors

View Source 
var SliceWriterError = errors.New("overflow in SliceWriter")

Functions

func CeilLog2 added in v0.35.0 

func CeilLog2(n uint) int

CeilLog2 returns nr bits needed to represent numbers 0 - n-1.

func EBSP2rbsp 

func EBSP2rbsp(ebsp []byte) []byte

EBSP2rbsp - convert from EBSP to RBSP by removing start code emulation prevention bytes

Types

type AccErrByteWriter 

type AccErrByteWriter struct {
	// contains filtered or unexported fields
}

AccErrByteWriter - writer that wraps an io.Writer and accumulates error

func NewAccErrByteWriter 

func NewAccErrByteWriter(w io.Writer) *AccErrByteWriter

NewAccErrByteWriter - create accumulated error writer around io.Writer

func (*AccErrByteWriter) AccError 

func (a *AccErrByteWriter) AccError() error

AccError - return accumulated error

func (*AccErrByteWriter) WriteSlice 

func (a *AccErrByteWriter) WriteSlice(s []byte)

WriteSlice - write a slice

func (*AccErrByteWriter) WriteUint16 

func (a *AccErrByteWriter) WriteUint16(u uint16)

WriteUint16 - write uint16

func (*AccErrByteWriter) WriteUint32 

func (a *AccErrByteWriter) WriteUint32(u uint32)

WriteUint32 - write uint32

func (*AccErrByteWriter) WriteUint48 

func (a *AccErrByteWriter) WriteUint48(u uint64)

WriteUint48 - write uint48

func (*AccErrByteWriter) WriteUint64 

func (a *AccErrByteWriter) WriteUint64(u uint64)

WriteUint64 - write uint64

func (*AccErrByteWriter) WriteUint8 

func (a *AccErrByteWriter) WriteUint8(b byte)

WriteUint8 - write a byte

type AccErrEBSPReader 

type AccErrEBSPReader struct {
	// contains filtered or unexported fields
}

AccErrEBSPReader - Reader that drops start code emulation 0x03 after two bytes of 0x00

func NewAccErrEBSPReader 

func NewAccErrEBSPReader(rd io.Reader) *AccErrEBSPReader

NewAccErrEBSPReader - return a new reader accumulating errors.

func (*AccErrEBSPReader) AccError 

func (r *AccErrEBSPReader) AccError() error

AccError - accumulated error

func (*AccErrEBSPReader) IsSeeker 

func (r *AccErrEBSPReader) IsSeeker() bool

IsSeeker - does reader support Seek

func (*AccErrEBSPReader) MoreRbspData 

func (r *AccErrEBSPReader) MoreRbspData() (bool, error)

MoreRbspData - false if next bit is 1 and last 1 in fullSlice. Underlying reader must support ReadSeeker interface to reset after check Return false, nil if underlying error

func (*AccErrEBSPReader) NrBitsRead added in v0.40.0 

func (r *AccErrEBSPReader) NrBitsRead() int

NrBitsRead - how many bits read into parser

func (*AccErrEBSPReader) NrBitsReadInCurrentByte 

func (r *AccErrEBSPReader) NrBitsReadInCurrentByte() int

NrBitsReadInCurrentByte - how many bits have been read

func (*AccErrEBSPReader) NrBytesRead 

func (r *AccErrEBSPReader) NrBytesRead() int

NrBytesRead - how many bytes read into parser

func (*AccErrEBSPReader) Read 

func (r *AccErrEBSPReader) Read(n int) uint

Read - read n bits and return 0 if (previous) error

func (*AccErrEBSPReader) ReadBytes 

func (r *AccErrEBSPReader) ReadBytes(n int) []byte

Read - read n bytes and return nil if (previous) error or if n bytes not available

func (*AccErrEBSPReader) ReadExpGolomb 

func (r *AccErrEBSPReader) ReadExpGolomb() uint

ReadExpGolomb - Read one unsigned exponential golomb code. Return 0 if error

func (*AccErrEBSPReader) ReadFlag 

func (r *AccErrEBSPReader) ReadFlag() bool

ReadFlag - read 1 bit into bool. Return false if not possible

func (*AccErrEBSPReader) ReadRbspTrailingBits 

func (r *AccErrEBSPReader) ReadRbspTrailingBits() error

ReadRbspTrailingBits - read rbsp_traling_bits. Return error if wrong pattern If other error, return nil and let AccError provide that error

func (*AccErrEBSPReader) ReadSignedGolomb 

func (r *AccErrEBSPReader) ReadSignedGolomb() int

ReadSignedGolomb - Read one signed exponential golomb code. Return 0 if error

func (*AccErrEBSPReader) SetError 

func (r *AccErrEBSPReader) SetError(err error)

SetError - set an error if not already set.

type AccErrReader 

type AccErrReader struct {
	// contains filtered or unexported fields
}

AccErrReader - bit reader that accumulates error First error can be fetched as reader.AccError()

func NewAccErrReader 

func NewAccErrReader(rd io.Reader) *AccErrReader

NewAccErrReader - return a new Reader

func (*AccErrReader) AccError 

func (r *AccErrReader) AccError() error

AccError - accumulated error is first error that occurred

func (*AccErrReader) Read 

func (r *AccErrReader) Read(n int) uint

Read - read n bits. Return 0, if error now or previously

func (*AccErrReader) ReadFlag 

func (r *AccErrReader) ReadFlag() bool

ReadFlag - read 1 bit into flag. Return false if error now or previously

func (*AccErrReader) ReadRemainingBytes 

func (r *AccErrReader) ReadRemainingBytes() []byte

ReadRemainingBytes - read remaining bytes if byte-aligned

func (*AccErrReader) ReadSigned added in v0.41.0 

func (r *AccErrReader) ReadSigned(n int) int

ReadSigned reads a 2-complemented signed int with n bits.

func (*AccErrReader) ReadVInt 

func (r *AccErrReader) ReadVInt(n int) int

ReadFlag - Read i(v) which is 2-complement of n bits

type EBSPReader 

type EBSPReader struct {
	// contains filtered or unexported fields
}

EBSPReader - Reader that drops start code emulation 0x03 after two bytes of 0x00

func NewEBSPReader 

func NewEBSPReader(rd io.Reader) *EBSPReader

NewEBSPReader - return a new Reader.

func (*EBSPReader) IsSeeker 

func (r *EBSPReader) IsSeeker() bool

IsSeeker - does reader support Seek

func (*EBSPReader) MoreRbspData 

func (r *EBSPReader) MoreRbspData() (bool, error)

MoreRbspData - false if next bit is 1 and last 1 in fullSlice Underlying reader must support ReadSeeker interface to reset after check

func (*EBSPReader) MustRead 

func (r *EBSPReader) MustRead(n int) uint

MustRead - read n bits and panic if not possible

func (*EBSPReader) MustReadExpGolomb 

func (r *EBSPReader) MustReadExpGolomb() uint

MustReadExpGolomb - Read one unsigned exponential golomb code. Panic if not possible

func (*EBSPReader) MustReadFlag 

func (r *EBSPReader) MustReadFlag() bool

MustReadFlag - read 1 bit into flag. Panic if not possible

func (*EBSPReader) MustReadSignedGolomb 

func (r *EBSPReader) MustReadSignedGolomb() int

MustReadSignedGolomb - Read one signed exponential golomb code. Panic if not possible

func (*EBSPReader) NrBitsReadInCurrentByte 

func (r *EBSPReader) NrBitsReadInCurrentByte() int

NrBitsReadInCurrentByte - how many bits have been read

func (*EBSPReader) NrBytesRead 

func (r *EBSPReader) NrBytesRead() int

NrBytesRead - how many bytes read into parser

func (*EBSPReader) Read 

func (r *EBSPReader) Read(n int) (uint, error)

Read - read n bits and return error if not possible

func (*EBSPReader) ReadExpGolomb 

func (r *EBSPReader) ReadExpGolomb() (uint, error)

ReadExpGolomb - Read one unsigned exponential golomb code

func (*EBSPReader) ReadFlag 

func (r *EBSPReader) ReadFlag() (bool, error)

ReadFlag - read 1 bit into flag. Return error if not possible

func (*EBSPReader) ReadRbspTrailingBits 

func (r *EBSPReader) ReadRbspTrailingBits() error

ReadRbspTrailingBits - read rbsp_traling_bits. Return false if wrong pattern

func (*EBSPReader) ReadSignedGolomb 

func (r *EBSPReader) ReadSignedGolomb() (int, error)

ReadSignedGolomb - Read one signed exponential golomb code

type EBSPWriter 

type EBSPWriter struct {
	// contains filtered or unexported fields
}

EBSPWriter - write bits and insert start-code emulation prevention bytes as necessary. Cease writing at first error. Errors that have occurred can later be checked with AccError().

func NewEBSPWriter 

func NewEBSPWriter(w io.Writer) *EBSPWriter

NewEBSPWriter - returns a new Writer

func (*EBSPWriter) AccError 

func (w *EBSPWriter) AccError() error

AccError - return accumulated error

func (*EBSPWriter) BitsInBuffer 

func (w *EBSPWriter) BitsInBuffer() (bits, n uint)

BitsInBuffer - n bits written in buffer byte, not written to underlying writer

func (*EBSPWriter) NrBitsInBuffer 

func (w *EBSPWriter) NrBitsInBuffer() uint

NrBitsInBuffer - number bits written in buffer byte

func (*EBSPWriter) StuffByteWithZeros 

func (w *EBSPWriter) StuffByteWithZeros()

StuffByteWithZeros - write zero bits until byte boundary (0-7bits)

func (*EBSPWriter) Write 

func (w *EBSPWriter) Write(bits uint, n int)

Write - write n bits from bits and save error state

func (*EBSPWriter) WriteExpGolomb 

func (w *EBSPWriter) WriteExpGolomb(nr uint)

WriteExpGolomb - write an exponential Golomb code

func (*EBSPWriter) WriteRbspTrailingBits 

func (w *EBSPWriter) WriteRbspTrailingBits()

WriteRbspTrailingBits - write rbsp trailing bits (a 1 followed by zeros to a byte boundary)

func (*EBSPWriter) WriteSEIValue 

func (w *EBSPWriter) WriteSEIValue(val uint)

WriteSEIValue insert 0xFF until value is less than 255. Used in SEI payload type and size.

type FixedSliceReader 

type FixedSliceReader struct {
	// contains filtered or unexported fields
}

FixedSliceReader - read integers and other data from a fixed slice. Accumulates error, and the first error can be retrieved. If err != nil, 0 or empty string is returned

func NewFixedSliceReader 

func NewFixedSliceReader(data []byte) *FixedSliceReader

bits.NewFixedSliceReader creates a new slice reader reading from data

func (*FixedSliceReader) AccError 

func (s *FixedSliceReader) AccError() error

AccError - get accumulated error after read operations

func (*FixedSliceReader) GetPos 

func (s *FixedSliceReader) GetPos() int

GetPos - get read position is slice

func (*FixedSliceReader) Length 

func (s *FixedSliceReader) Length() int

Length - get length of slice

func (*FixedSliceReader) LookAhead added in v0.33.0 

func (s *FixedSliceReader) LookAhead(offset int, data []byte) error

LookAhead returns data ahead of current pos if within bounds.

func (*FixedSliceReader) NrRemainingBytes 

func (s *FixedSliceReader) NrRemainingBytes() int

NrRemainingBytes - return number of bytes remaining

func (*FixedSliceReader) ReadBytes 

func (s *FixedSliceReader) ReadBytes(n int) []byte

ReadBytes - read a slice of n bytes Return empty slice if n bytes not available

func (*FixedSliceReader) ReadFixedLengthString 

func (s *FixedSliceReader) ReadFixedLengthString(n int) string

ReadFixedLengthString - read string of specified length n. Sets err and returns empty string if full length not available

func (*FixedSliceReader) ReadInt16 

func (s *FixedSliceReader) ReadInt16() int16

ReadInt16 - read int16 from slice

func (*FixedSliceReader) ReadInt32 

func (s *FixedSliceReader) ReadInt32() int32

ReadInt32 - read int32 from slice

func (*FixedSliceReader) ReadInt64 

func (s *FixedSliceReader) ReadInt64() int64

ReadInt64 - read int64 from slice

func (*FixedSliceReader) ReadUint16 

func (s *FixedSliceReader) ReadUint16() uint16

ReadUint16 - read uint16 from slice

func (*FixedSliceReader) ReadUint24 

func (s *FixedSliceReader) ReadUint24() uint32

ReadUint24 - read uint24 from slice

func (*FixedSliceReader) ReadUint32 

func (s *FixedSliceReader) ReadUint32() uint32

ReadUint32 - read uint32 from slice

func (*FixedSliceReader) ReadUint64 

func (s *FixedSliceReader) ReadUint64() uint64

ReadUint64 - read uint64 from slice

func (*FixedSliceReader) ReadUint8 

func (s *FixedSliceReader) ReadUint8() byte

ReadUint8 - read uint8 from slice

func (*FixedSliceReader) ReadZeroTerminatedString 

func (s *FixedSliceReader) ReadZeroTerminatedString(maxLen int) string

ReadZeroTerminatedString - read string until zero byte but at most maxLen Set err and return empty string if no zero byte found

func (*FixedSliceReader) RemainingBytes 

func (s *FixedSliceReader) RemainingBytes() []byte

RemainingBytes - return remaining bytes of this slice

func (*FixedSliceReader) SetPos 

func (s *FixedSliceReader) SetPos(pos int)

SetPos - set read position is slice

func (*FixedSliceReader) SkipBytes 

func (s *FixedSliceReader) SkipBytes(n int)

SkipBytes - skip passed n bytes

type FixedSliceWriter 

type FixedSliceWriter struct {
	// contains filtered or unexported fields
}

FixedSliceWriter - write numbers to a fixed []byte slice

func NewFixedSliceWriter 

func NewFixedSliceWriter(size int) *FixedSliceWriter

NewSliceWriter - create slice writer with fixed size.

func NewFixedSliceWriterFromSlice 

func NewFixedSliceWriterFromSlice(data []byte) *FixedSliceWriter

NewFixedSliceWriter - create writer around slice. The slice will not grow, but stay the same size. If too much data is written, there will be an accumuluated error. Can be retrieved with AccError()

func (*FixedSliceWriter) AccError 

func (sw *FixedSliceWriter) AccError() error

AccError - return accumulated erro

func (*FixedSliceWriter) Bytes 

func (sw *FixedSliceWriter) Bytes() []byte

Bytes - return buf up to what's written

func (*FixedSliceWriter) Capacity 

func (sw *FixedSliceWriter) Capacity() int

Capacity - max length of FixedSliceWriter buffer

func (*FixedSliceWriter) FlushBits 

func (sw *FixedSliceWriter) FlushBits()

FlushBits - write remaining bits to the underlying .Writer. bits will be left-shifted and zeros appended to fill up a byte.

func (*FixedSliceWriter) Len 

func (sw *FixedSliceWriter) Len() int

Len - length of FixedSliceWriter buffer written. Same as Offset()

func (*FixedSliceWriter) Offset 

func (sw *FixedSliceWriter) Offset() int

Offset - offset for writing in FixedSliceWriter buffer

func (*FixedSliceWriter) WriteBits 

func (sw *FixedSliceWriter) WriteBits(bits uint, n int)

func (*FixedSliceWriter) WriteBytes 

func (sw *FixedSliceWriter) WriteBytes(byteSlice []byte)

WriteBytes - write []byte

func (*FixedSliceWriter) WriteFlag 

func (sw *FixedSliceWriter) WriteFlag(f bool)

WriteFlag writes a flag as 1 bit.

func (*FixedSliceWriter) WriteInt16 

func (sw *FixedSliceWriter) WriteInt16(n int16)

WriteInt16 - write int16 to slice

func (*FixedSliceWriter) WriteInt32 

func (sw *FixedSliceWriter) WriteInt32(n int32)

WriteInt32 - write int32 to slice

func (*FixedSliceWriter) WriteInt64 

func (sw *FixedSliceWriter) WriteInt64(n int64)

WriteInt64 - write int64 to slice

func (*FixedSliceWriter) WriteString 

func (sw *FixedSliceWriter) WriteString(s string, addZeroEnd bool)

WriteString - write string to slice with or without zero end

func (*FixedSliceWriter) WriteUint16 

func (sw *FixedSliceWriter) WriteUint16(n uint16)

WriteUint16 - write uint16 to slice

func (*FixedSliceWriter) WriteUint24 

func (sw *FixedSliceWriter) WriteUint24(n uint32)

WriteUint24 - write uint24 to slice

func (*FixedSliceWriter) WriteUint32 

func (sw *FixedSliceWriter) WriteUint32(n uint32)

WriteUint32 - write uint32 to slice

func (*FixedSliceWriter) WriteUint48 

func (sw *FixedSliceWriter) WriteUint48(u uint64)

WriteUint48 - write uint48

func (*FixedSliceWriter) WriteUint64 

func (sw *FixedSliceWriter) WriteUint64(n uint64)

WriteUint64 - write uint64 to slice

func (*FixedSliceWriter) WriteUint8 

func (sw *FixedSliceWriter) WriteUint8(n byte)

WriteUint8 - write byte to slice

func (*FixedSliceWriter) WriteUnityMatrix 

func (sw *FixedSliceWriter) WriteUnityMatrix()

WriteUnityMatrix - write a unity matrix for mvhd or tkhd

func (*FixedSliceWriter) WriteZeroBytes 

func (sw *FixedSliceWriter) WriteZeroBytes(n int)

WriteZeroBytes - write n byte of zeroes

type Reader 

type Reader struct {
	// contains filtered or unexported fields
}

Reader - read bits from the given io.Reader

func NewReader 

func NewReader(rd io.Reader) *Reader

NewReader - return a new Reader

func (*Reader) MustRead 

func (r *Reader) MustRead(n int) uint

MustRead - Read bits and panic if not possible

func (*Reader) MustReadFlag 

func (r *Reader) MustReadFlag() bool

MustReadFlag - read 1 bit into flag and panic if not possible

func (*Reader) Read 

func (r *Reader) Read(n int) (uint, error)

Read - read n bits

func (*Reader) ReadFlag 

func (r *Reader) ReadFlag() (bool, error)

ReadFlag - read 1 bit into flag

type SliceReader 

type SliceReader interface {
	AccError() error
	ReadUint8() byte
	ReadUint16() uint16
	ReadInt16() int16
	ReadUint24() uint32
	ReadUint32() uint32
	ReadInt32() int32
	ReadUint64() uint64
	ReadInt64() int64
	ReadFixedLengthString(n int) string
	ReadZeroTerminatedString(maxLen int) string
	ReadBytes(n int) []byte
	RemainingBytes() []byte
	NrRemainingBytes() int
	SkipBytes(n int)
	SetPos(pos int)
	GetPos() int
	Length() int
	LookAhead(offset int, data []byte) error
}

type SliceWriter 

type SliceWriter interface {
	Len() int
	Capacity() int
	Offset() int
	Bytes() []byte
	AccError() error
	WriteUint8(n byte)
	WriteUint16(n uint16)
	WriteInt16(n int16)
	WriteUint24(n uint32)
	WriteUint32(n uint32)
	WriteInt32(n int32)
	WriteUint48(u uint64)
	WriteUint64(n uint64)
	WriteInt64(n int64)
	WriteString(s string, addZeroEnd bool)
	WriteZeroBytes(n int)
	WriteBytes(byteSlice []byte)
	WriteUnityMatrix()
	WriteBits(bits uint, n int)
	WriteFlag(f bool)
	FlushBits()
}

type Writer 

type Writer struct {
	// contains filtered or unexported fields
}

Writer writes bits into underlying io.Writer. Stops writing at first error. Errors that have occurred can later be checked with Error().

func NewWriter 

func NewWriter(w io.Writer) *Writer

NewWriter - returns a new Writer

func (*Writer) Error 

func (w *Writer) Error() error

Error - error that has occurred and stopped writing

func (*Writer) Flush 

func (w *Writer) Flush()

Flush - write remaining bits to the underlying io.Writer. bits will be left-shifted.

func (*Writer) Write 

func (w *Writer) Write(bits uint, n int)

Write - write n bits from bits and save error state

Source Files

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