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Improving mpegts file to allow for setting of pcr
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@ -1,7 +1,7 @@
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/*
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/*
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NAME
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NAME
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MpegTs.go - provides a data structure intended to encapsulate the properties
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MpegTs.go - provides a data structure intended to encapsulate the properties
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of an MpegTs packet.
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of an MpegTs packet and also functions to allow manipulation of these packets.
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DESCRIPTION
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DESCRIPTION
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See Readme.md
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See Readme.md
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@ -28,77 +28,106 @@ LICENSE
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package packets
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package packets
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import _ "fmt"
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/*
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The below data struct encapsulates the fields of an MPEG-TS packet. Below is
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// Length of some fields in bits
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the formatting of an MPEG-TS packet for reference!
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const (
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syncByteLength = 8
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teiLength = 1
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pusiLength = 1
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priorityLength = 1
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pidLength = 13
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tscLength = 2
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afcLength = 2
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ccLength = 4
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packetLength = 188
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)
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// Index of the fields
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const (
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syncByteIndex = 0
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teiIndex = syncByteIndex + syncByteLength
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pusiIndex = teiIndex + teiLength
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priorityIndex = pusiIndex + pusiLength
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pidIndex = priorityIndex + priorityLength
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tscIndex = pidIndex + pidLength
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afcIndex = tscIndex + tscLength
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ccIndex = afcIndex + afcLength
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afIndex = ccIndex + ccLength
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)
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MPEG-TS Packet Formatting
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============================================================================
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| octet no | bit 0 | bit 1 | bit 2 | bit 3 | bit 4 | bit 5 | bit 6 | bit 7 |
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============================================================================
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| octet 0 | sync byte (0x47) |
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----------------------------------------------------------------------------
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| octet 1 | TEI | PUSI | Prior | PID |
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----------------------------------------------------------------------------
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| octet 2 | PID cont. |
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----------------------------------------------------------------------------
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| octet 3 | TSC | AFC | CC |
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----------------------------------------------------------------------------
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| octet 4 | AFL |
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----------------------------------------------------------------------------
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| octet 5 | DI | RAI | ESPI | PCRF | OPCRF | SPF | TPDF | AFEF |
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----------------------------------------------------------------------------
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| optional | PCR (48 bits => 6 bytes) |
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----------------------------------------------------------------------------
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| - | PCR cont. |
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----------------------------------------------------------------------------
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| - | PCR cont. |
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----------------------------------------------------------------------------
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| - | PCR cont. |
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----------------------------------------------------------------------------
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| - | PCR cont. |
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----------------------------------------------------------------------------
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| - | PCR cont. |
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----------------------------------------------------------------------------
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| optional | OPCR (48 bits => 6 bytes) |
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----------------------------------------------------------------------------
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| - | OPCR cont. |
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----------------------------------------------------------------------------
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| - | OPCR cont. |
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----------------------------------------------------------------------------
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| - | OPCR cont. |
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----------------------------------------------------------------------------
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| - | OPCR cont. |
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----------------------------------------------------------------------------
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| - | OPCR cont. |
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----------------------------------------------------------------------------
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| optional | SC |
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----------------------------------------------------------------------------
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| optional | TPDL |
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----------------------------------------------------------------------------
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| optional | TPD (variable length) |
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----------------------------------------------------------------------------
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| - | ... |
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----------------------------------------------------------------------------
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| optional | Extension (variable length) |
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----------------------------------------------------------------------------
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| - | ... |
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----------------------------------------------------------------------------
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| optional | Stuffing (variable length) |
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----------------------------------------------------------------------------
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| - | ... |
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----------------------------------------------------------------------------
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| optional | Payload (variable length) |
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----------------------------------------------------------------------------
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| - | ... |
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----------------------------------------------------------------------------
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*/
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type MpegTsPacket struct {
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type MpegTsPacket struct {
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// syncByte byte // (octet:0 bit:0 - octet:0 bit:7)
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TEI bool // Transport Error Indicator
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TEI bool // (octet:1 bit:0) Transport Error Indicator
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PUSI bool // Payload Unit Start Indicator
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PUSI bool // (octet:1 bit:1) Payload Unit Start Indicator
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Priority bool // Tranposrt priority indicator
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Priority bool // (octet:1 bit:2) Tranposrt priority indicator
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PID uint16 // Packet identifier
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PID uint16 // (octet:1 bit:3 - octect:3 bit:7) Packet identifier
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TSC byte // Transport Scrambling Control
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TSC byte // (octet:4 bit:0 - octect:4 bit:1) Transport Scrambling Control
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AFC byte // Adaption Field Control
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AFC byte // (octet:4 bit:2 - octect:4 bit:3) Adaption Field Control
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CC byte // Continuity Counter
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CC byte // (octet:4 bit:4 - octect:4 bit:7) Continuity Counter
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AFL byte // Adaptation field length
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AFL byte // (octet:5 bit:0 - octect:5 bit:7) Adaptation field length
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DI bool // Discontinouty indicator
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DI bool // (octet:6 bit:0) Discontinouty indicator
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RAI bool // random access indicator
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RAI bool // (octet:6 bit:1) random access indicator
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ESPI bool // Elementary stream priority indicator
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ESPI bool // (octet:6 bit:2) Elementary stream priority indicator
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PCRF bool // PCR flag
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PCRF bool // (octet:6 bit:3) pcr flag
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OPCRF bool // OPCR flag
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OPCRF bool // (octet:6 bit:4) opcr flag
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SPF bool // Splicing point flag
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SPF bool // (octet:6 bit:5) splicing point flag
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TPDF bool // Transport private data flag
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TPDF bool // (octet:6 bit:6) transport private data flag
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AFEF bool // Adaptation field extension flag
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AFEF bool // (octet:6 bit:7) adaptation field extension flag
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PCR uint64 // Program clock reference
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PCR uint64 // (optional 48 bits) program clock reference
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OPCR uint64 // Original program clock reference
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OPCR uint64 // (optional 48 bits) Original program clock reference
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SC byte // Splice countdown
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SC byte // (optional 8 bits) splice countdown
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TPDL byte // Tranposrt private data length
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TPDL byte // (optional 8 bits) tranposrt private data length
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TPD []byte // Private data
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TPD []byte // (optional variable length) private data
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Extension []byte // Adaptation field extension
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Extension []byte // (optional variable length) adaptation field extension
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Stuffing []byte // Stuffing bytes
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Stuffing []byte // (optional variable length) stuffing bytes
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Payload []byte // Mpeg ts payload
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Payload []byte // (optional variable length) mpeg ts payload
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}
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}
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func (p *MpegTsPacket) ToByteSlice() (output []byte) {
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func (p *MpegTsPacket) ToByteSlice() (output []byte) {
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output = make([]byte, 188)
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output = make([]byte, 188)
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output[0] = 0x47 // sync byte always the same
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output[0] = 0x47
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output[1] = (boolToByte(p.TEI) << (7 - teiIndex%8)) |
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output[1] = boolToByte(p.TEI) << 7 | boolToByte(p.PUSI) << 6 |
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(boolToByte(p.PUSI) << (7 - pusiIndex%8)) |
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boolToByte(p.Priority) << 5 | byte((p.PID&0xFF00) >> 8)
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(boolToByte(p.Priority) << (7 - priorityIndex%8)) |
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byte((p.PID&0xFF00)>>8)
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output[2] = byte(p.PID & 0x00FF)
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output[2] = byte(p.PID & 0x00FF)
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output[3] = (p.TSC << 6) | (p.AFC << 4) | p.CC
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output[3] = p.TSC << 6 | (p.AFC << 4) | p.CC
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for ii := 4; ii-4 < len(p.AF); ii++ {
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output[4] = p.AFL
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output[ii] = p.AF[ii-4]
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output[5] =
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}
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payloadIndex := 4 + len(p.AF)
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for ii := payloadIndex; ii < packetLength; ii++ {
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output[ii] = p.Payload[ii-payloadIndex]
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}
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return
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return
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}
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}
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