2018-02-13 11:39:26 +03:00
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/*
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NAME
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2018-08-19 14:09:57 +03:00
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encoder.go
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2018-02-13 11:39:26 +03:00
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AUTHOR
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2018-08-18 04:57:36 +03:00
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Dan Kortschak <dan@ausocean.org>
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2018-02-28 16:46:59 +03:00
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Saxon Nelson-Milton <saxon@ausocean.org>
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2018-02-13 11:39:26 +03:00
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LICENSE
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2018-08-19 14:09:57 +03:00
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encoder.go is Copyright (C) 2017-2018 the Australian Ocean Lab (AusOcean)
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2018-02-13 11:39:26 +03:00
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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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2018-08-18 04:57:36 +03:00
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along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.
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2018-02-13 11:39:26 +03:00
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*/
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2018-08-18 04:57:36 +03:00
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2018-08-19 13:59:22 +03:00
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package mts
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2017-12-30 11:31:50 +03:00
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2018-02-12 10:58:29 +03:00
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import (
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2018-10-19 03:50:08 +03:00
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"io"
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2018-08-18 06:51:50 +03:00
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"time"
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2019-03-25 04:21:03 +03:00
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"bitbucket.org/ausocean/av/container/mts/meta"
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"bitbucket.org/ausocean/av/container/mts/pes"
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"bitbucket.org/ausocean/av/container/mts/psi"
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2018-12-10 10:14:56 +03:00
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)
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2019-01-07 09:43:50 +03:00
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// Some common manifestations of PSI
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var (
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2019-01-10 03:42:33 +03:00
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// standardPat is a minimal PAT.
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2019-01-08 12:16:24 +03:00
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standardPat = psi.PSI{
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2019-01-07 09:43:50 +03:00
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Pf: 0x00,
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Tid: 0x00,
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Ssi: true,
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Pb: false,
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Sl: 0x0d,
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Tss: &psi.TSS{
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Tide: 0x01,
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V: 0,
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Cni: true,
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Sn: 0,
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Lsn: 0,
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Sd: &psi.PAT{
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Pn: 0x01,
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Pmpid: 0x1000,
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},
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},
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}
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2019-01-11 14:59:48 +03:00
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// standardPmt is a minimal PMT, without descriptors for time and location.
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2019-01-08 12:16:24 +03:00
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standardPmt = psi.PSI{
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2019-01-07 09:43:50 +03:00
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Pf: 0x00,
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Tid: 0x02,
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Ssi: true,
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Sl: 0x12,
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Tss: &psi.TSS{
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Tide: 0x01,
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V: 0,
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Cni: true,
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Sn: 0,
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Lsn: 0,
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Sd: &psi.PMT{
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2019-01-08 12:14:33 +03:00
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Pcrpid: 0x0100,
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2019-01-07 09:43:50 +03:00
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Pil: 0,
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Essd: &psi.ESSD{
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St: 0x1b,
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Epid: 0x0100,
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Esil: 0x00,
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},
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},
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},
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}
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)
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2018-11-20 17:21:57 +03:00
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const (
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2019-02-16 09:03:39 +03:00
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psiInterval = 1 * time.Second
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psiSendCount = 7
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2018-11-20 17:21:57 +03:00
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)
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2018-04-17 08:20:23 +03:00
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2019-02-07 00:59:51 +03:00
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// Meta allows addition of metadata to encoded mts from outside of this pkg.
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// See meta pkg for usage.
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2019-02-07 01:01:02 +03:00
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//
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// TODO: make this not global.
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2019-02-06 02:49:12 +03:00
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var Meta *meta.Data
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2019-02-05 05:44:42 +03:00
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2018-12-14 08:39:53 +03:00
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var (
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2019-01-08 12:16:24 +03:00
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patTable = standardPat.Bytes()
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2019-01-26 10:34:21 +03:00
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pmtTable = standardPmt.Bytes()
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2018-12-14 08:39:53 +03:00
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)
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2018-02-28 17:42:00 +03:00
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2018-01-16 08:49:18 +03:00
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const (
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2019-04-05 08:58:25 +03:00
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sdtPid = 17
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patPid = 0
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pmtPid = 4096
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videoPid = 256
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audioPid = 210
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videoStreamID = 0xe0 // First video stream ID.
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audioStreamID = 0xc0 // First audio stream ID.
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)
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// Video and Audio constants are used to communicate which media type will be encoded when creating a
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// new encoder with NewEncoder.
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const (
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Video = iota
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Audio
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2018-08-18 10:49:26 +03:00
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)
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// Time related constants.
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const (
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// ptsOffset is the offset added to the clock to determine
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2019-01-08 12:12:46 +03:00
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// the current presentation timestamp.
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2018-08-18 06:51:50 +03:00
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ptsOffset = 700 * time.Millisecond
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2018-08-18 10:49:26 +03:00
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// pcrFreq is the base Program Clock Reference frequency.
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pcrFreq = 90000 // Hz
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2018-01-16 08:49:18 +03:00
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)
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2019-05-11 14:44:28 +03:00
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// Encoder encapsulates properties of an MPEG-TS generator.
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2018-08-19 14:09:57 +03:00
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type Encoder struct {
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2019-04-15 02:12:56 +03:00
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dst io.WriteCloser
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2018-08-18 07:06:14 +03:00
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2019-04-05 08:58:25 +03:00
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clock time.Duration
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lastTime time.Time
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writePeriod time.Duration
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ptsOffset time.Duration
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tsSpace [PacketSize]byte
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pesSpace [pes.MaxPesSize]byte
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2018-08-18 07:06:14 +03:00
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continuity map[int]byte
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2019-01-24 07:03:22 +03:00
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2019-02-16 09:03:39 +03:00
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timeBasedPsi bool
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pktCount int
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psiSendCount int
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2019-04-05 08:58:25 +03:00
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mediaPid int
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streamID byte
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2019-02-16 09:03:39 +03:00
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2019-01-24 07:03:22 +03:00
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psiLastTime time.Time
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2017-12-13 09:52:18 +03:00
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}
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2019-04-10 10:48:42 +03:00
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// NewEncoder returns an Encoder with the specified media type and rate eg. if a video stream
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// calls write for every frame, the rate will be the frame rate of the video.
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2019-04-15 02:12:56 +03:00
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func NewEncoder(dst io.WriteCloser, rate float64, mediaType int) *Encoder {
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2019-04-05 08:58:25 +03:00
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var mPid int
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var sid byte
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switch mediaType {
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case Audio:
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mPid = audioPid
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sid = audioStreamID
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case Video:
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mPid = videoPid
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sid = videoStreamID
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}
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2018-08-19 14:09:57 +03:00
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return &Encoder{
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2018-10-19 03:50:08 +03:00
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dst: dst,
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2018-08-18 07:06:14 +03:00
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2019-04-10 10:48:42 +03:00
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writePeriod: time.Duration(float64(time.Second) / rate),
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2019-04-05 08:58:25 +03:00
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ptsOffset: ptsOffset,
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2018-08-18 07:06:14 +03:00
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2019-02-16 09:03:39 +03:00
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timeBasedPsi: true,
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pktCount: 8,
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2019-04-05 08:58:25 +03:00
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mediaPid: mPid,
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streamID: sid,
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2018-08-18 04:57:36 +03:00
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continuity: map[int]byte{
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2019-04-05 08:58:25 +03:00
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patPid: 0,
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pmtPid: 0,
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mPid: 0,
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2018-08-18 04:57:36 +03:00
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},
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}
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2018-01-08 04:12:26 +03:00
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}
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2018-08-18 10:49:26 +03:00
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const (
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hasPayload = 0x1
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hasAdaptationField = 0x2
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)
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const (
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hasDTS = 0x1
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hasPTS = 0x2
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)
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2019-03-02 05:51:46 +03:00
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// TimeBasedPsi allows for the setting of the PSI writing method, therefore, if
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// PSI is written based on some time duration, or based on a packet count.
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// If b is true, then time based PSI is used, otherwise the PSI is written
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// every sendCount.
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2019-02-16 09:03:39 +03:00
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func (e *Encoder) TimeBasedPsi(b bool, sendCount int) {
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e.timeBasedPsi = b
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e.psiSendCount = sendCount
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2019-02-16 20:05:59 +03:00
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e.pktCount = e.psiSendCount
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2019-02-16 09:03:39 +03:00
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}
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2019-05-11 14:44:28 +03:00
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// Write implements io.Writer. Write takes raw h264 and encodes into MPEG-TS,
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2019-03-10 05:34:15 +03:00
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// then sending it to the encoder's io.Writer destination.
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2019-04-05 08:58:25 +03:00
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func (e *Encoder) Write(data []byte) (int, error) {
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2019-01-24 07:09:14 +03:00
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now := time.Now()
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2019-02-28 10:49:06 +03:00
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if (e.timeBasedPsi && (now.Sub(e.psiLastTime) > psiInterval)) || (!e.timeBasedPsi && (e.pktCount >= e.psiSendCount)) {
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2019-02-16 20:05:59 +03:00
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e.pktCount = 0
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2019-01-23 08:20:25 +03:00
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err := e.writePSI()
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if err != nil {
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2019-03-10 05:30:58 +03:00
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return 0, err
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2019-01-23 08:20:25 +03:00
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}
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2019-01-24 07:09:14 +03:00
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e.psiLastTime = now
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2019-01-23 08:20:25 +03:00
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}
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2019-01-24 07:03:22 +03:00
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2018-08-19 14:58:20 +03:00
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// Prepare PES data.
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pesPkt := pes.Packet{
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2019-04-05 08:58:25 +03:00
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StreamID: e.streamID,
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2018-08-19 14:58:20 +03:00
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PDI: hasPTS,
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PTS: e.pts(),
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2019-04-05 08:58:25 +03:00
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Data: data,
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2018-08-19 14:58:20 +03:00
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HeaderLength: 5,
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}
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2019-04-05 08:58:25 +03:00
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2019-01-02 03:06:46 +03:00
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buf := pesPkt.Bytes(e.pesSpace[:pes.MaxPesSize])
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2018-08-19 14:58:20 +03:00
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pusi := true
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for len(buf) != 0 {
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pkt := Packet{
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PUSI: pusi,
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2019-04-05 08:58:25 +03:00
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PID: uint16(e.mediaPid),
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2018-08-19 14:58:20 +03:00
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RAI: pusi,
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2019-04-05 08:58:25 +03:00
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CC: e.ccFor(e.mediaPid),
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2018-08-19 14:58:20 +03:00
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AFC: hasAdaptationField | hasPayload,
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PCRF: pusi,
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2018-08-18 04:57:36 +03:00
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}
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2018-08-19 14:58:20 +03:00
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n := pkt.FillPayload(buf)
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buf = buf[n:]
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if pusi {
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// If the packet has a Payload Unit Start Indicator
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// flag set then we need to write a PCR.
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pkt.PCR = e.pcr()
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pusi = false
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2018-01-04 10:04:33 +03:00
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}
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2019-01-12 10:06:35 +03:00
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_, err := e.dst.Write(pkt.Bytes(e.tsSpace[:PacketSize]))
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2018-10-19 03:50:08 +03:00
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if err != nil {
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2019-04-05 08:58:25 +03:00
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return len(data), err
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2018-10-19 03:50:08 +03:00
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}
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2019-02-16 09:03:39 +03:00
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e.pktCount++
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2018-01-04 10:04:33 +03:00
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}
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2018-08-19 14:58:20 +03:00
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e.tick()
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2019-04-05 08:58:25 +03:00
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return len(data), nil
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2017-12-13 09:52:18 +03:00
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}
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2018-08-18 04:57:36 +03:00
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2019-05-11 14:44:28 +03:00
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// writePSI creates MPEG-TS with pat and pmt tables - with pmt table having updated
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2018-12-14 09:16:36 +03:00
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// location and time data.
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2018-11-21 05:04:00 +03:00
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func (e *Encoder) writePSI() error {
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2019-01-08 12:12:46 +03:00
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// Write PAT.
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2018-11-21 05:04:00 +03:00
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patPkt := Packet{
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2019-01-30 08:07:15 +03:00
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PUSI: true,
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PID: PatPid,
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CC: e.ccFor(PatPid),
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2019-05-07 16:40:03 +03:00
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AFC: hasPayload,
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2019-01-30 08:07:15 +03:00
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Payload: psi.AddPadding(patTable),
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2018-11-21 05:04:00 +03:00
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}
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2019-01-12 10:06:35 +03:00
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_, err := e.dst.Write(patPkt.Bytes(e.tsSpace[:PacketSize]))
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2018-11-21 05:04:00 +03:00
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if err != nil {
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return err
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}
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2019-02-16 09:03:39 +03:00
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e.pktCount++
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2019-02-05 15:54:00 +03:00
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pmtTable, err = updateMeta(pmtTable)
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2019-02-05 15:48:05 +03:00
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if err != nil {
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2019-01-30 08:07:15 +03:00
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return err
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}
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2018-12-13 04:52:06 +03:00
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2019-01-08 12:12:46 +03:00
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// Create mts packet from pmt table.
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2018-11-21 05:04:00 +03:00
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pmtPkt := Packet{
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2019-01-30 08:07:15 +03:00
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PUSI: true,
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PID: PmtPid,
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CC: e.ccFor(PmtPid),
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2019-05-07 16:40:03 +03:00
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AFC: hasPayload,
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2019-01-30 08:07:15 +03:00
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Payload: psi.AddPadding(pmtTable),
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2018-11-21 05:04:00 +03:00
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}
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2019-01-12 10:06:35 +03:00
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_, err = e.dst.Write(pmtPkt.Bytes(e.tsSpace[:PacketSize]))
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2018-11-21 05:04:00 +03:00
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if err != nil {
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return err
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}
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2019-02-16 09:03:39 +03:00
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e.pktCount++
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2018-11-21 05:04:00 +03:00
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return nil
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}
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2018-08-18 07:06:14 +03:00
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// tick advances the clock one frame interval.
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2018-08-19 14:09:57 +03:00
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|
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func (e *Encoder) tick() {
|
2019-04-05 08:58:25 +03:00
|
|
|
e.clock += e.writePeriod
|
2018-08-18 07:06:14 +03:00
|
|
|
}
|
|
|
|
|
|
|
|
// pts retuns the current presentation timestamp.
|
2018-08-19 14:09:57 +03:00
|
|
|
func (e *Encoder) pts() uint64 {
|
|
|
|
return uint64((e.clock + e.ptsOffset).Seconds() * pcrFreq)
|
2018-08-18 04:57:36 +03:00
|
|
|
}
|
|
|
|
|
2018-08-18 07:06:14 +03:00
|
|
|
// pcr returns the current program clock reference.
|
2018-08-19 14:09:57 +03:00
|
|
|
func (e *Encoder) pcr() uint64 {
|
|
|
|
return uint64(e.clock.Seconds() * pcrFreq)
|
2018-08-18 04:57:36 +03:00
|
|
|
}
|
|
|
|
|
|
|
|
// ccFor returns the next continuity counter for pid.
|
2018-08-19 14:09:57 +03:00
|
|
|
func (e *Encoder) ccFor(pid int) byte {
|
|
|
|
cc := e.continuity[pid]
|
2019-01-12 10:04:43 +03:00
|
|
|
const continuityCounterMask = 0xf
|
|
|
|
e.continuity[pid] = (cc + 1) & continuityCounterMask
|
2018-08-18 04:57:36 +03:00
|
|
|
return cc
|
|
|
|
}
|
2019-01-26 15:12:31 +03:00
|
|
|
|
2019-02-04 14:47:39 +03:00
|
|
|
// updateMeta adds/updates a metaData descriptor in the given psi bytes using data
|
|
|
|
// contained in the global Meta struct.
|
2019-02-05 15:54:00 +03:00
|
|
|
func updateMeta(b []byte) ([]byte, error) {
|
|
|
|
p := psi.PSIBytes(b)
|
2019-02-01 04:09:47 +03:00
|
|
|
err := p.AddDescriptor(psi.MetadataTag, Meta.Encode())
|
2019-02-05 15:54:00 +03:00
|
|
|
return []byte(p), err
|
2019-01-26 15:12:31 +03:00
|
|
|
}
|
2019-04-15 02:12:56 +03:00
|
|
|
|
|
|
|
func (e *Encoder) Close() error {
|
|
|
|
return e.dst.Close()
|
|
|
|
}
|