av/stream/mts/psi/psi.go

package psi

const (
	ESSDDefLen = 5
	DescDefLen = 2
	PMTDefLen  = 4
	PATLen     = 4
)

// Program specific information
type PSI struct {
	pf  byte   // Point field
	pfb []byte // Pointer filler bytes
	tid byte   // Table ID
	ssi bool   // Section syntax indicator (1 for PAT, PMT, CAT)
	pb  bool   // Private bit (0 for PAT, PMT, CAT)
	sl  uint16 // Section length
	tss *TSS   // Table syntax section (length defined by SL) if length 0 then nil
}

// Table syntax section
type TSS struct {
	tie uint16 // Table ID extension
	v   byte   // Version number
	cni bool   // Current/next indicator
	sn  byte   // Section number
	lsn byte   // Last section number
	sd  SD     // Specific data PAT/PMT
	crc []byte // crc32 of entire table excluding pointer field, pointer filler bytes and the trailing CRC32
}

// Specific Data, (could be PAT or PMT)
type SD interface {
	Bytes() []byte
}

// Program association table, implements SD
type PAT struct {
	pn    uint16 // Program Number
	pmpid uint16 // Program map PID
}

// Program mapping table, implements SD
type PMT struct {
	pcrpid uint16 // Program clock reference pid
	pil    uint16 // Program info length
	pd     []Desc // Program descriptors
	essd   []ESSD // Elementary stream specific data
}

// Elementary stream specific data
type ESSD struct {
	st   byte   // Stream type
	epid uint16 // Elementary pid
	esil uint16 // Elementary stream
	esd  []Desc // Elementary stream desriptors
}

// Descriptor
type Desc struct {
	dt byte   // Descriptor tag
	dl byte   // Descriptor length
	dd []byte // Descriptor data
}

func ReadPSI(data []byte) *PSI {
	return nil
}

func (p *PSI) Bytes() (out []byte) {
	return nil
}

func (t *TSS) Fill(s []byte) {
}

func (p *PAT) Bytes() []byte {
	out := make([]byte, PATLen)
	out[0] = byte(p.pn >> 8)
	out[1] = byte(p.pn)
	out[2] = 0xe0 | (0x1f & byte(p.pmpid>>8))
	out[3] = byte(p.pmpid)
	return out
}

func (p *PMT) Bytes() []byte {
	out := make([]byte, PMTDefLen)
	out[0] = 0xe0 | (0x1f & byte(p.pcrpid>>8))
	out[1] = byte(p.pcrpid)
	out[2] = 0xf0 | (0x03 & byte(p.pil>>8))
	out[3] = byte(p.pil)
	for _, d := range p.pd {
		out = append(out, d.Bytes()...)
	}
	for _, e := range p.essd {
		out = append(out, e.Bytes()...)
	}
	return out
}

func (d *Desc) Bytes() []byte {
	out := make([]byte, DescDefLen)
	out[0] = d.dt
	out[1] = d.dl
	out = append(out, d.dd...)
	return out
}

func (e *ESSD) Bytes() []byte {
	out := make([]byte, ESSDDefLen)
	out[0] = e.st
	out[1] = 0xe0 | (0x1f & byte(e.epid>>8))
	out[2] = byte(e.epid)
	out[3] = 0xf0 | (0x03 & byte(e.esil>>8))
	out[4] = byte(e.esil)
	for _, d := range e.esd {
		out = append(out, d.Bytes()...)
	}
	return out
}