|
|
// Copyright 2019, Chef. All rights reserved.
|
|
|
// https://github.com/q191201771/lal
|
|
|
//
|
|
|
// Use of this source code is governed by a MIT-style license
|
|
|
// that can be found in the License file.
|
|
|
//
|
|
|
// Author: Chef (191201771@qq.com)
|
|
|
|
|
|
package aac
|
|
|
|
|
|
import (
|
|
|
"errors"
|
|
|
|
|
|
"github.com/q191201771/naza/pkg/nazabits"
|
|
|
"github.com/q191201771/naza/pkg/nazalog"
|
|
|
)
|
|
|
|
|
|
// AudioSpecificConfig(asc)
|
|
|
// keywords: Seq Header,
|
|
|
// e.g. rtmp, flv
|
|
|
//
|
|
|
// ADTS
|
|
|
// e.g. ts
|
|
|
//
|
|
|
// StreamMuxConfig
|
|
|
//
|
|
|
|
|
|
var ErrAac = errors.New("lal.aac: fxxk")
|
|
|
|
|
|
const minAscLength = 2
|
|
|
|
|
|
// Audio Data Transport Stream
|
|
|
type Adts struct {
|
|
|
audioObjectType uint8
|
|
|
samplingFrequencyIndex uint8
|
|
|
channelConfiguration uint8
|
|
|
|
|
|
adtsHeader []byte
|
|
|
}
|
|
|
|
|
|
type SequenceHeader struct {
|
|
|
soundFormat uint8
|
|
|
soundRate uint8
|
|
|
soundSize uint8
|
|
|
soundType uint8
|
|
|
aacPacketType uint8
|
|
|
}
|
|
|
|
|
|
// @param <asc> 2字节的AAC Audio Specifc Config
|
|
|
// 函数调用结束后，内部不持有<asc>内存块
|
|
|
// 注意，如果是rtmp/flv的message/tag，应去除Seq Header头部的2个字节
|
|
|
//
|
|
|
func (a *Adts) InitWithAacAudioSpecificConfig(asc []byte) error {
|
|
|
if len(asc) < minAscLength {
|
|
|
nazalog.Warnf("aac seq header length invalid. len=%d", len(asc))
|
|
|
return ErrAac
|
|
|
}
|
|
|
|
|
|
// <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
|
|
|
br := nazabits.NewBitReader(asc)
|
|
|
a.audioObjectType, _ = br.ReadBits8(5)
|
|
|
a.samplingFrequencyIndex, _ = br.ReadBits8(4)
|
|
|
a.channelConfiguration, _ = br.ReadBits8(4)
|
|
|
//nazalog.Debugf("%+v", a)
|
|
|
|
|
|
if a.adtsHeader == nil {
|
|
|
a.adtsHeader = make([]byte, 7)
|
|
|
}
|
|
|
|
|
|
return nil
|
|
|
}
|
|
|
|
|
|
// 获取ADTS头，由于ADTS头中的字段依赖包的长度，而每个包的长度不同，所以生成的每个包的ADTS头也不同
|
|
|
//
|
|
|
// @param <length> 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 返回的内存块，内部会继续持有，重复使用
|
|
|
//
|
|
|
func (a *Adts) CalcAdtsHeader(length uint16) ([]byte, error) {
|
|
|
if !a.HasInited() {
|
|
|
nazalog.Warn("calc adts header but asc not inited.")
|
|
|
return nil, ErrAac
|
|
|
}
|
|
|
// <ISO_IEC_14496-3.pdf>
|
|
|
// <1.A.2.2.1 Fixed Header of ADTS>, <page 75/110>
|
|
|
// <1.A.2.2.2 Variable Header of ADTS>, <page 76/110>
|
|
|
// <1.A.3.2.1 Definitions: Bitstream elements for ADTS>
|
|
|
// ----------------------------------------------------
|
|
|
// Syncword [12b] '1111 1111 1111'
|
|
|
// ID [1b] 1=MPEG-2 AAC 0=MPEG-4
|
|
|
// Layer [2b]
|
|
|
// protection_absent [1b] 1=no crc check
|
|
|
// Profile_ObjectType [2b]
|
|
|
// sampling_frequency_index [4b]
|
|
|
// private_bit [1b]
|
|
|
// channel_configuration [3b]
|
|
|
// origin/copy [1b]
|
|
|
// home [1b]
|
|
|
// Emphasis???
|
|
|
// ------------------------------------
|
|
|
// copyright_identification_bit [1b]
|
|
|
// copyright_identification_start [1b]
|
|
|
// aac_frame_length [13b]
|
|
|
// adts_buffer_fullness [11b]
|
|
|
// no_raw_data_blocks_in_frame [2b]
|
|
|
|
|
|
// 加上自身adts头的7个字节
|
|
|
length += 7
|
|
|
|
|
|
bw := nazabits.NewBitWriter(a.adtsHeader)
|
|
|
// Syncword 0(8) 1(4)
|
|
|
bw.WriteBits16(12, 0xFFF)
|
|
|
// ID, Layer, protection_absent 1(4)
|
|
|
bw.WriteBits8(4, 0x1)
|
|
|
// 2(2)
|
|
|
bw.WriteBits8(2, a.audioObjectType-1)
|
|
|
// 2(4)
|
|
|
bw.WriteBits8(4, a.samplingFrequencyIndex)
|
|
|
// private_bit 2(1)
|
|
|
bw.WriteBits8(1, 0)
|
|
|
// 2(1) 3(2)
|
|
|
bw.WriteBits8(3, a.channelConfiguration)
|
|
|
// origin/copy, home, copyright_identification_bit, copyright_identification_start 3(4)
|
|
|
bw.WriteBits8(4, 0)
|
|
|
// 3(2) 4(8) 5(3)
|
|
|
bw.WriteBits16(13, length)
|
|
|
// adts_buffer_fullness 5(5) 6(6)
|
|
|
bw.WriteBits16(11, 0x7FF)
|
|
|
// no_raw_data_blocks_in_frame 6(2)
|
|
|
bw.WriteBits8(2, 0)
|
|
|
|
|
|
return a.adtsHeader, nil
|
|
|
}
|
|
|
|
|
|
// 可用于判断，是否调用过ADTS.InitWithAacAudioSpecificConfig
|
|
|
func (a *Adts) HasInited() bool {
|
|
|
return a.adtsHeader != nil
|
|
|
}
|
|
|
|
|
|
// @param <b> rtmp/flv的message/tag的payload部分，包含前面2个字节
|
|
|
// 函数调用结束后，内部不持有<b>内存块
|
|
|
func ParseAacSeqHeader(b []byte) (sh SequenceHeader, adts Adts, err error) {
|
|
|
if len(b) < 4 {
|
|
|
nazalog.Warnf("aac seq header length invalid. len=%d", len(b))
|
|
|
err = ErrAac
|
|
|
return
|
|
|
}
|
|
|
|
|
|
// <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
|
|
|
br := nazabits.NewBitReader(b)
|
|
|
sh.soundFormat, _ = br.ReadBits8(4)
|
|
|
sh.soundRate, _ = br.ReadBits8(2)
|
|
|
sh.soundSize, _ = br.ReadBits8(1)
|
|
|
sh.soundType, _ = br.ReadBits8(1)
|
|
|
sh.aacPacketType, _ = br.ReadBits8(8)
|
|
|
//nazalog.Debugf("%s %+v", hex.Dump(payload[:4]), sh)
|
|
|
|
|
|
err = adts.InitWithAacAudioSpecificConfig(b[2:])
|
|
|
return
|
|
|
}
|
|
|
|
|
|
// @param <asc> 函数调用结束后，内部不继续持有<asc>内存块
|
|
|
//
|
|
|
// @return 返回的内存块为新申请的独立内存块
|
|
|
//
|
|
|
func BuildAacSeqHeader(asc []byte) ([]byte, error) {
|
|
|
if len(asc) < minAscLength {
|
|
|
return nil, ErrAac
|
|
|
}
|
|
|
|
|
|
ret := make([]byte, 2+len(asc))
|
|
|
// <spec-video_file_format_spec_v10.pdf>, <Audio tags, AUDIODATA>, <page 10/48>
|
|
|
ret[0] = 0xaf
|
|
|
ret[1] = 0
|
|
|
copy(ret[2:], asc)
|
|
|
return ret, nil
|
|
|
}
|