avc

Documentation

Index

• Constants
• func ContainsNaluType(sample []byte, specificNalType NaluType) bool
• func GetParameterSets(sample []byte) (sps [][]byte, pps [][]byte)
• func HasParameterSets(b []byte) bool
• func IsIDRSample(sample []byte) bool
• type AVCDecoderConfigurationRecord
  • func (b *AVCDecoderConfigurationRecord) RecordRead(r io.Reader) (err error)
  • func (b *AVCDecoderConfigurationRecord) RecordSize() (size uint32)
  • func (b *AVCDecoderConfigurationRecord) RecordWrite(w io.Writer) (err error)
• type AVCPictureParameterSet
• type AVCSequenceParameterSet
• type AVCSequenceParameterSetExt
• type NaluType
  • func FindNaluTypes(sample []byte) []NaluType
  • func GetNaluType(naluHeader byte) NaluType
  • func (a NaluType) String() string

Constants

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_SSP - 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)
)

Functions

func ContainsNaluType

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

ContainsNaluType - is specific NaluType present in sample

func GetParameterSets

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

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

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

Types

type AVCDecoderConfigurationRecord

type AVCDecoderConfigurationRecord struct {
	ConfigurationVersion uint8

	// contains the profile code as defined in ISO/IEC 14496-10.
	AVCProfileIndication uint8

	// is a byte defined exactly the same as the byte that occurs between the
	// profile_IDC and level_IDC in a sequence parameter set (SPS), as defined
	// in ISO/IEC 14496-10.
	ProfileCompatibility uint8

	// contains the level code as defined in ISO/IEC 14496-10.
	AVCLevelIndication uint8

	// indicates the length in bytes of the NALUnitLength field in an AVC video
	// sample or AVC parameter set sample of the associated stream minus one.
	// For example, a size of one byte is indicated with a value of 0. The value
	// of this field shall be one of 0, 1, or 3 corresponding to a length
	// encoded with 1, 2, or 4 bytes, respectively.
	LengthSizeMinusOne uint8

	// SPSs that are used as the initial set of SPSs for decoding the AVC
	// elementary stream.
	SequenceParameterSets []AVCSequenceParameterSet

	// picture parameter sets (PPSs) that are used as the initial set of PPSs
	// for decoding the AVC elementary stream.
	PictureParameterSets []AVCPictureParameterSet

	// contains the chroma_format indicator as defined by the chroma_format_idc
	// parameter in ISO/IEC 14496-10.
	ChromaFormat uint8

	// indicates the bit depth of the samples in the Luma arrays. For example, a
	// bit depth of 8 is indicated with a value of zero (BitDepth = 8 +
	// bit_depth_luma_minus8). The value of this field shall be in the range of
	// 0 to 4, inclusive.
	BitDepthLumaMinus8 uint8

	// indicates the bit depth of the samples in the Chroma arrays. For example,
	// a bit depth of 8 is indicated with a value of zero (BitDepth = 8 +
	// bit_depth_chroma_minus8). The value of this field shall be in the range
	// of 0 to 4, inclusive.
	BitDepthChromaMinus8 uint8

	// Sequence Parameter Set Extensions that are used for decoding the AVC
	// elementary stream.
	SequenceParameterSetExts []AVCSequenceParameterSetExt
}

This record contains the size of the length field used in each sample to indicate the length of its contained NAL units as well as the initial parameter sets. This record is externally framed (its size shall be supplied by the structure that contains it).

This record contains a version field. This version of the specification defines version 1 of this record. Incompatible changes to the record will be indicated by a change of version number. Readers shall not attempt to decode this record or the streams to which it applies if the version number is unrecognized.

Compatible extensions to this record will extend it and will not change the configuration version code. Readers should be prepared to ignore unrecognized data beyond the definition of the data they understand (e.g. after the parameter sets in this specification).

When used to provide the configuration of

— a parameter set elementary stream, and
— a video elementary stream used in conjunction with a parameter set
  elementary stream,

the configuration record shall contain no sequence or picture parameter sets (numOfSequenceParameterSets and numOfPictureParameterSets shall both have the value 0).

When used to provide the configuration of a video elementary stream used without a parameter set elementary stream, the configuration record may or may not contain sequence or picture parameter sets (numOfSequenceParameterSets or numOfPictureParameterSets may or may not have the value 0).

The values for AVCProfileIndication, AVCLevelIndication, and the flags that indicate profile compatibility shall be valid for all parameter sets of the stream described by this record. The level indication shall indicate a level of capability equal to or greater than the highest level indicated in the included parameter sets; each profile compatibility flag may only be set if all the included parameter sets set that flag. The profile indication shall indicate a profile to which the entire stream associated with this configuration record conforms. If the sequence parameter sets are marked with different profiles, and the relevant profile compatibility flags are all zero, then the stream may need examination to determine which profile, if any, the entire stream conforms to. If the entire stream is not examined, or the examination reveals that there is no profile to which the entire stream conforms, then the stream shall be split into two or more sub-streams with separate configuration records in which these rules can be met.

Explicit indication can be provided in the AVC Decoder Configuration Record about the chroma format and bit depth used by the AVC video elementary stream. The parameter ʹchroma_format_idcʹ present in the sequence parameter set in AVC specifies the chroma sampling relative to the luma sampling. Similarly the parameters ʹbit_depth_luma_minus8ʹ and ʹbit_depth_chroma_minus8ʹ in the sequence parameter set specify the bit depth of the samples of the luma and chroma arrays. The values of chroma_format_idc, bit_depth_luma_minus8ʹ and ʹbit_depth_chroma_minus8ʹ shall be identical in all sequence parameter sets in a single AVC configuration record. If two sequences differ in any of these values, two different AVC configuration records will be needed. If the two sequences differ in color space indications in their VUI information, then two different configuration records are also required.

The array of sequence parameter sets, and the array of picture parameter sets, may contain SEI messages of a “declarative” nature, that is, those that provide information about the stream as a whole. An example of such an SEI is a user-data SEI. Such SEIs may also be placed in a parameter set elementary stream. NAL unit types that are reserved in ISO/IEC 14496-10 and in this specification may acquire a definition in future, and readers should ignore NAL units with reserved values of NAL unit type when they are present in these arrays.

NOTE 1 This “tolerant” behaviour is designed so that errors are not raised, allowing the possibility of backwards-compatible extensions to these arrays in future specifications.

When Sequence Parameter Set Extension NAL units occur in this record in profiles other than those indicated for the array specific to such NAL units (profile_idc not equal to any of 100, 110, 122, 144), they should be placed in the Sequence Parameter Set Array.

NOTE 2 The profile identified by profile_idc value 144 is deprecated in ISO/IEC 14496-10.

func (*AVCDecoderConfigurationRecord) RecordRead

func (b *AVCDecoderConfigurationRecord) RecordRead(r io.Reader) (err error)

func (*AVCDecoderConfigurationRecord) RecordSize

func (b *AVCDecoderConfigurationRecord) RecordSize() (size uint32)

func (*AVCDecoderConfigurationRecord) RecordWrite

func (b *AVCDecoderConfigurationRecord) RecordWrite(w io.Writer) (err error)

type AVCPictureParameterSet

type AVCPictureParameterSet struct {
	// contains a PPS NAL unit, as specified in ISO/IEC 14496-10. PPSs shall
	// occur in order of ascending parameter set identifier with gaps being
	// allowed.
	NALUnit []byte
}

type AVCSequenceParameterSet

type AVCSequenceParameterSet struct {
	// contains a SPS NAL unit, as specified in ISO/IEC 14496-10. SPSs shall
	// occur in order of ascending parameter set identifier with gaps being
	// allowed.
	NALUnit []byte
}

type AVCSequenceParameterSetExt

type AVCSequenceParameterSetExt struct {
	// contains a SPS Extension NAL unit, as specified in ISO/IEC 14496-10.
	NALUnit []byte
}

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 GetNaluType

func GetNaluType(naluHeader byte) NaluType

Get NaluType from NAL Unit Header byte

func (NaluType) String

func (a NaluType) String() string