mirror of https://bitbucket.org/ausocean/av.git
92 lines
2.5 KiB
Go
92 lines
2.5 KiB
Go
/*
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NAME
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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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DESCRIPTION
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See Readme.md
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AUTHOR
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Saxon Nelson-Milton <saxon.milton@gmail.com>
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LICENSE
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MpegTs.go is Copyright (C) 2017 the Australian Ocean Lab (AusOcean)
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It is free software: you can redistribute it and/or modify them
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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It is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with revid in gpl.txt. If not, see [GNU licenses](http://www.gnu.org/licenses).
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*/
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package packet
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// Length of some fields in bits
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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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type MpegTsPacket struct {
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SyncByte byte
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TEI bool // Transport Error Indicator
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PUSI bool // Payload Unit Start Indicator
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Priority bool
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PID uint16
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TSC byte // Transport Scrambling Control
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AFC byte // Adaption Field Control
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CC byte // Continuity Counter
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AF []byte // Adaption Field
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Payload []byte
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}
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func boolToByte( in bool ) (out uint8){
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if in { out = 1 }
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return
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}
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func (p *MpegTsPacket) ToByteSlice() (output [188]byte) {
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output[0] = p.SyncByte
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output[1] = ( boolToByte(p.TEI) << (8-teiIndex%8) ) |
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( boolToByte(p.PUSI) << (8-pusiIndex%8) ) |
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( boolToByte(p.Priority) << (8-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[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[ii] = p.AF[ii-4]
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}
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headerSize := packetLength-len(p.Payload)
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for ii := headerSize; ii < packetLength; ii++ {
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output[ii] = p.Payload[ii-headerSize]
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}
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return
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}
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