aac

Documentation

Index

• Constants
• Variables
• func MakeAscWithAdtsHeader(adtsHeader []byte) (asc []byte, err error)
• func MakeAudioDataSeqHeaderWithAdtsHeader(adtsHeader []byte) (out []byte, err error)
• func MakeAudioDataSeqHeaderWithAsc(asc []byte) (out []byte, err error)
• type AdtsHeaderContext
  • func NewAdtsHeaderContext(adtsHeader []byte) (*AdtsHeaderContext, error)
  • func (ctx *AdtsHeaderContext) Unpack(adtsHeader []byte) error
• type AscContext
  • func NewAscContext(asc []byte) (*AscContext, error)
  • func (ascCtx *AscContext) GetSamplingFrequency() (int, error)
  • func (ascCtx *AscContext) Pack() (asc []byte)
  • func (ascCtx *AscContext) PackAdtsHeader(frameLength int) (out []byte)
  • func (ascCtx *AscContext) PackToAdtsHeader(out []byte, frameLength int) error
  • func (ascCtx *AscContext) Unpack(asc []byte) error
• type SequenceHeaderContext
  • func (shCtx *SequenceHeaderContext) Unpack(b []byte)

Constants

const (
	AdtsHeaderLength = 7

	AscSamplingFrequencyIndex48000 = 3
	AscSamplingFrequencyIndex44100 = 4
)

Variables

var ErrAac = errors.New("lal.aac: fxxk")

Functions

func MakeAscWithAdtsHeader

func MakeAscWithAdtsHeader(adtsHeader []byte) (asc []byte, err error)

@param adtsHeader: 函数调用结束后，内部不持有该内存块

@return asc: 内存块为独立新申请；函数调用结束后，内部不持有该内存块

func MakeAudioDataSeqHeaderWithAdtsHeader

func MakeAudioDataSeqHeaderWithAdtsHeader(adtsHeader []byte) (out []byte, err error)

@param adtsHeader: 函数调用结束后，内部不持有该内存块

@return out: 内存块为独立新申请；函数调用结束后，内部不持有该内存块

func MakeAudioDataSeqHeaderWithAsc

func MakeAudioDataSeqHeaderWithAsc(asc []byte) (out []byte, err error)

@param asc: 函数调用结束后，内部不持有该内存块

@return out: 内存块为独立新申请；函数调用结束后，内部不持有该内存块

Types

type AdtsHeaderContext

type AdtsHeaderContext struct {
	AscCtx AscContext

	AdtsLength uint16 // 字段中的值，包含了adts header + adts frame
}

func NewAdtsHeaderContext

func NewAdtsHeaderContext(adtsHeader []byte) (*AdtsHeaderContext, error)

func (*AdtsHeaderContext) Unpack

func (ctx *AdtsHeaderContext) Unpack(adtsHeader []byte) error

@param adtsHeader: 函数调用结束后，内部不持有该内存块

type AscContext

type AscContext struct {
	AudioObjectType        uint8 // [5b]
	SamplingFrequencyIndex uint8 // [4b]
	ChannelConfiguration   uint8 // [4b]
}

<ISO_IEC_14496-3.pdf> <1.6.2.1 AudioSpecificConfig>, <page 33/110> <1.5.1.1 Audio Object type definition>, <page 23/110> <1.6.3.3 samplingFrequencyIndex>, <page 35/110> <1.6.3.4 channelConfiguration> -------------------------------------------------------- audio object type [5b] 1=AAC MAIN 2=AAC LC samplingFrequencyIndex [4b] 3=48000 4=44100 6=24000 5=32000 11=11025 channelConfiguration [4b] 1=center front speaker 2=left, right front speakers

func NewAscContext

func NewAscContext(asc []byte) (*AscContext, error)

func (*AscContext) GetSamplingFrequency

func (ascCtx *AscContext) GetSamplingFrequency() (int, error)

func (*AscContext) Pack

func (ascCtx *AscContext) Pack() (asc []byte)

@return asc: 内存块为独立新申请；函数调用结束后，内部不持有该内存块

func (*AscContext) PackAdtsHeader

func (ascCtx *AscContext) PackAdtsHeader(frameLength int) (out []byte)

获取ADTS头，由于ADTS头中的字段依赖包的长度，而每个包的长度可能不同，所以每个包的ADTS头都需要独立生成

@param frameLength: raw aac frame的大小

注意，如果是rtmp/flv的message/tag，应去除Seq Header头部的2个字节

@return h: 内存块为独立新申请；函数调用结束后，内部不持有该内存块

func (*AscContext) PackToAdtsHeader

func (ascCtx *AscContext) PackToAdtsHeader(out []byte, frameLength int) error

@param out: 函数调用结束后，内部不持有该内存块

func (*AscContext) Unpack

func (ascCtx *AscContext) Unpack(asc []byte) error

@param asc: 2字节的AAC Audio Specifc Config

注意，如果是rtmp/flv的message/tag，应去除Seq Header头部的2个字节
函数调用结束后，内部不持有该内存块

type SequenceHeaderContext

type SequenceHeaderContext struct {
	SoundFormat   uint8 // [4b]
	SoundRate     uint8 // [2b]
	SoundSize     uint8 // [1b]
	SoundType     uint8 // [1b]
	AacPacketType uint8 // [8b]
}

<spec-video_file_format_spec_v10.pdf>, <Audio tags, AUDIODATA>, <page 10/48> ---------------------------------------------------------------------------- soundFormat [4b] 10=AAC soundRate [2b] 3=44kHz. AAC always 3 soundSize [1b] 0=snd8Bit, 1=snd16Bit soundType [1b] 0=sndMono, 1=sndStereo. AAC always 1 aacPackageType [8b] 0=seq header, 1=AAC raw

func (*SequenceHeaderContext) Unpack

func (shCtx *SequenceHeaderContext) Unpack(b []byte)

@param b: rtmp/flv的message/tag的payload的前2个字节

函数调用结束后，内部不持有该内存块