551 lines
15 KiB
Go
551 lines
15 KiB
Go
package isom
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import (
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"bytes"
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"fmt"
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"github.com/nareix/bits"
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"io"
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"io/ioutil"
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)
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// copied from libavformat/isom.h
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const (
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MP4ESDescrTag = 3
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MP4DecConfigDescrTag = 4
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MP4DecSpecificDescrTag = 5
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)
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var debugReader = false
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var debugWriter = false
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// copied from libavcodec/mpeg4audio.h
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const (
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AOT_AAC_MAIN = 1 + iota ///< Y Main
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AOT_AAC_LC ///< Y Low Complexity
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AOT_AAC_SSR ///< N (code in SoC repo) Scalable Sample Rate
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AOT_AAC_LTP ///< Y Long Term Prediction
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AOT_SBR ///< Y Spectral Band Replication
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AOT_AAC_SCALABLE ///< N Scalable
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AOT_TWINVQ ///< N Twin Vector Quantizer
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AOT_CELP ///< N Code Excited Linear Prediction
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AOT_HVXC ///< N Harmonic Vector eXcitation Coding
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AOT_TTSI = 12 + iota ///< N Text-To-Speech Interface
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AOT_MAINSYNTH ///< N Main Synthesis
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AOT_WAVESYNTH ///< N Wavetable Synthesis
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AOT_MIDI ///< N General MIDI
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AOT_SAFX ///< N Algorithmic Synthesis and Audio Effects
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AOT_ER_AAC_LC ///< N Error Resilient Low Complexity
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AOT_ER_AAC_LTP = 19 + iota ///< N Error Resilient Long Term Prediction
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AOT_ER_AAC_SCALABLE ///< N Error Resilient Scalable
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AOT_ER_TWINVQ ///< N Error Resilient Twin Vector Quantizer
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AOT_ER_BSAC ///< N Error Resilient Bit-Sliced Arithmetic Coding
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AOT_ER_AAC_LD ///< N Error Resilient Low Delay
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AOT_ER_CELP ///< N Error Resilient Code Excited Linear Prediction
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AOT_ER_HVXC ///< N Error Resilient Harmonic Vector eXcitation Coding
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AOT_ER_HILN ///< N Error Resilient Harmonic and Individual Lines plus Noise
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AOT_ER_PARAM ///< N Error Resilient Parametric
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AOT_SSC ///< N SinuSoidal Coding
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AOT_PS ///< N Parametric Stereo
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AOT_SURROUND ///< N MPEG Surround
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AOT_ESCAPE ///< Y Escape Value
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AOT_L1 ///< Y Layer 1
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AOT_L2 ///< Y Layer 2
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AOT_L3 ///< Y Layer 3
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AOT_DST ///< N Direct Stream Transfer
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AOT_ALS ///< Y Audio LosslesS
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AOT_SLS ///< N Scalable LosslesS
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AOT_SLS_NON_CORE ///< N Scalable LosslesS (non core)
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AOT_ER_AAC_ELD ///< N Error Resilient Enhanced Low Delay
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AOT_SMR_SIMPLE ///< N Symbolic Music Representation Simple
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AOT_SMR_MAIN ///< N Symbolic Music Representation Main
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AOT_USAC_NOSBR ///< N Unified Speech and Audio Coding (no SBR)
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AOT_SAOC ///< N Spatial Audio Object Coding
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AOT_LD_SURROUND ///< N Low Delay MPEG Surround
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AOT_USAC ///< N Unified Speech and Audio Coding
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)
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type MPEG4AudioConfig struct {
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SampleRate int
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ChannelCount int
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ObjectType uint
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SampleRateIndex uint
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ChannelConfig uint
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}
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var sampleRateTable = []int{
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96000, 88200, 64000, 48000, 44100, 32000,
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24000, 22050, 16000, 12000, 11025, 8000, 7350,
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}
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var chanConfigTable = []int{
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0, 1, 2, 3, 4, 5, 6, 8,
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}
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func IsADTSPayload(frames []byte) bool {
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return len(frames) > 7 && frames[0]==0xff&&frames[1]&0xf0==0xf0
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}
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func ReadADTSPayload(frames []byte) (config MPEG4AudioConfig, payload []byte, n int, next []byte, err error) {
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if !IsADTSPayload(frames) {
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err = fmt.Errorf("not adts frame")
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return
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}
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config.ObjectType = uint(frames[2]>>6)+1
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config.SampleRateIndex = uint(frames[2]>>2&0xf)
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config.ChannelConfig = uint(frames[2]<<2&0x4|frames[3]>>6&0x3)
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framelen := int(frames[3]&0x3)<<11|int(frames[4])<<3|int(frames[5]>>5)
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n = (int(frames[6]&0x3)+1)*1024
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hdrlen := 7
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if frames[1]&0x1 == 0 {
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hdrlen = 9
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}
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if framelen < hdrlen || len(frames) < framelen {
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err = fmt.Errorf("invalid adts header length")
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return
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}
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payload = append(payload, frames[hdrlen:framelen]...)
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next = frames[framelen:]
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return
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}
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func ExtractADTSPayload(frames []byte) (config MPEG4AudioConfig, payload []byte, total int, err error) {
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for len(frames) > 0 {
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var n int
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if config, payload, n, frames, err = ReadADTSPayload(frames); err != nil {
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return
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}
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total += n
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}
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return
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}
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func ReadADTSHeader(data []byte) (config MPEG4AudioConfig, frameLength int) {
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br := &bits.Reader{R: bytes.NewReader(data)}
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var i uint
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//Structure
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//AAAAAAAA AAAABCCD EEFFFFGH HHIJKLMM MMMMMMMM MMMOOOOO OOOOOOPP (QQQQQQQQ QQQQQQQQ)
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//Header consists of 7 or 9 bytes (without or with CRC).
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// 2 bytes
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//A 12 syncword 0xFFF, all bits must be 1
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br.ReadBits(12)
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//B 1 MPEG Version: 0 for MPEG-4, 1 for MPEG-2
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br.ReadBits(1)
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//C 2 Layer: always 0
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br.ReadBits(2)
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//D 1 protection absent, Warning, set to 1 if there is no CRC and 0 if there is CRC
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br.ReadBits(1)
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//E 2 profile, the MPEG-4 Audio Object Type minus 1
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config.ObjectType, _ = br.ReadBits(2)
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config.ObjectType++
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//F 4 MPEG-4 Sampling Frequency Index (15 is forbidden)
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config.SampleRateIndex, _ = br.ReadBits(4)
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//G 1 private bit, guaranteed never to be used by MPEG, set to 0 when encoding, ignore when decoding
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br.ReadBits(1)
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//H 3 MPEG-4 Channel Configuration (in the case of 0, the channel configuration is sent via an inband PCE)
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config.ChannelConfig, _ = br.ReadBits(3)
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//I 1 originality, set to 0 when encoding, ignore when decoding
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br.ReadBits(1)
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//J 1 home, set to 0 when encoding, ignore when decoding
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br.ReadBits(1)
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//K 1 copyrighted id bit, the next bit of a centrally registered copyright identifier, set to 0 when encoding, ignore when decoding
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br.ReadBits(1)
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//L 1 copyright id start, signals that this frame's copyright id bit is the first bit of the copyright id, set to 0 when encoding, ignore when decoding
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br.ReadBits(1)
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//M 13 frame length, this value must include 7 or 9 bytes of header length: FrameLength = (ProtectionAbsent == 1 ? 7 : 9) + size(AACFrame)
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i, _ = br.ReadBits(13)
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frameLength = int(i)
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//O 11 Buffer fullness
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br.ReadBits(11)
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//P 2 Number of AAC frames (RDBs) in ADTS frame minus 1, for maximum compatibility always use 1 AAC frame per ADTS frame
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br.ReadBits(2)
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//Q 16 CRC if protection absent is 0
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return
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}
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func readObjectType(r *bits.Reader) (objectType uint, err error) {
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if objectType, err = r.ReadBits(5); err != nil {
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return
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}
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if objectType == AOT_ESCAPE {
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var i uint
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if i, err = r.ReadBits(6); err != nil {
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return
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}
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objectType = 32 + i
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}
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return
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}
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func writeObjectType(w *bits.Writer, objectType uint) (err error) {
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if objectType >= 32 {
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if err = w.WriteBits(AOT_ESCAPE, 5); err != nil {
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return
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}
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if err = w.WriteBits(objectType-32, 6); err != nil {
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return
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}
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} else {
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if err = w.WriteBits(objectType, 5); err != nil {
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return
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}
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}
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return
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}
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func readSampleRateIndex(r *bits.Reader) (index uint, err error) {
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if index, err = r.ReadBits(4); err != nil {
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return
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}
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if index == 0xf {
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if index, err = r.ReadBits(24); err != nil {
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return
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}
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}
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return
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}
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func writeSampleRateIndex(w *bits.Writer, index uint) (err error) {
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if index >= 0xf {
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if err = w.WriteBits(0xf, 4); err != nil {
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return
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}
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if err = w.WriteBits(index, 24); err != nil {
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return
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}
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} else {
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if err = w.WriteBits(index, 4); err != nil {
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return
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}
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}
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return
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}
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func (self MPEG4AudioConfig) IsValid() bool {
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return self.ObjectType > 0
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}
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func (self MPEG4AudioConfig) Complete() (config MPEG4AudioConfig) {
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config = self
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if int(config.SampleRateIndex) < len(sampleRateTable) {
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config.SampleRate = sampleRateTable[config.SampleRateIndex]
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}
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if int(config.ChannelConfig) < len(chanConfigTable) {
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config.ChannelCount = chanConfigTable[config.ChannelConfig]
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}
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return
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}
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// copied from libavcodec/mpeg4audio.c avpriv_mpeg4audio_get_config()
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func ReadMPEG4AudioConfig(r io.Reader) (config MPEG4AudioConfig, err error) {
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br := &bits.Reader{R: r}
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if config.ObjectType, err = readObjectType(br); err != nil {
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return
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}
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if config.SampleRateIndex, err = readSampleRateIndex(br); err != nil {
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return
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}
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if config.ChannelConfig, err = br.ReadBits(4); err != nil {
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return
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}
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return
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}
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func WriteMPEG4AudioConfig(w io.Writer, config MPEG4AudioConfig) (err error) {
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bw := &bits.Writer{W: w}
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if err = writeObjectType(bw, config.ObjectType); err != nil {
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return
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}
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if config.SampleRateIndex == 0 {
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for i, rate := range sampleRateTable {
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if rate == config.SampleRate {
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config.SampleRateIndex = uint(i)
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}
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}
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}
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if err = writeSampleRateIndex(bw, config.SampleRateIndex); err != nil {
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return
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}
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if config.ChannelConfig == 0 {
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for i, count := range chanConfigTable {
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if count == config.ChannelCount {
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config.ChannelConfig = uint(i)
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}
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}
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}
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if err = bw.WriteBits(config.ChannelConfig, 4); err != nil {
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return
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}
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if err = bw.FlushBits(); err != nil {
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return
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}
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return
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}
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func readDesc(r io.Reader) (tag uint, data []byte, err error) {
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if tag, err = bits.ReadUIntBE(r, 8); err != nil {
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return
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}
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var length uint
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for i := 0; i < 4; i++ {
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var c uint
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if c, err = bits.ReadUIntBE(r, 8); err != nil {
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return
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}
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length = (length << 7) | (c & 0x7f)
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if c&0x80 == 0 {
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break
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}
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}
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data = make([]byte, length)
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if _, err = r.Read(data); err != nil {
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return
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}
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return
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}
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func writeDesc(w io.Writer, tag uint, data []byte) (err error) {
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if err = bits.WriteUIntBE(w, tag, 8); err != nil {
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return
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}
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length := uint(len(data))
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for i := 3; i > 0; i-- {
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if err = bits.WriteUIntBE(w, (length>>uint(7*i))&0x7f|0x80, 8); err != nil {
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return
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}
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}
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if err = bits.WriteUIntBE(w, length&0x7f, 8); err != nil {
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return
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}
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if _, err = w.Write(data); err != nil {
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return
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}
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return
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}
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func readESDesc(r io.Reader) (err error) {
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var ES_ID uint
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// ES_ID
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if ES_ID, err = bits.ReadUIntBE(r, 16); err != nil {
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return
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}
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var flags uint
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if flags, err = bits.ReadUIntBE(r, 8); err != nil {
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return
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}
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//streamDependenceFlag
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if flags&0x80 != 0 {
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if _, err = bits.ReadUIntBE(r, 16); err != nil {
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return
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}
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}
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//URL_Flag
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if flags&0x40 != 0 {
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var length uint
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if length, err = bits.ReadUIntBE(r, 8); err != nil {
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return
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}
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if _, err = io.CopyN(ioutil.Discard, r, int64(length)); err != nil {
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return
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}
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}
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//OCRstreamFlag
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if flags&0x20 != 0 {
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if _, err = bits.ReadUIntBE(r, 16); err != nil {
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return
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}
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}
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if debugReader {
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println("readESDesc:", ES_ID, flags)
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}
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return
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}
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func writeESDesc(w io.Writer, ES_ID uint) (err error) {
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// ES_ID
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if err = bits.WriteUIntBE(w, ES_ID, 16); err != nil {
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return
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}
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// flags
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if err = bits.WriteUIntBE(w, 0, 8); err != nil {
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return
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}
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return
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}
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func readDescByTag(r io.Reader, targetTag uint) (data []byte, err error) {
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var found bool
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for {
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if tag, _data, err := readDesc(r); err != nil {
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break
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} else {
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if tag == targetTag {
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data = _data
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found = true
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}
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if debugReader {
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println("readDescByTag:", tag, len(_data))
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}
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}
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}
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if !found {
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err = fmt.Errorf("tag not found")
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return
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}
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return
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}
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// copied from libavformat/isom.c ff_mp4_read_dec_config_descr()
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func readDecConfDesc(r io.Reader) (decConfig []byte, err error) {
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var objectId uint
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var streamType uint
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var bufSize uint
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var maxBitrate uint
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var avgBitrate uint
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// objectId
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if objectId, err = bits.ReadUIntBE(r, 8); err != nil {
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return
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}
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// streamType
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if streamType, err = bits.ReadUIntBE(r, 8); err != nil {
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return
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}
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// buffer size db
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if bufSize, err = bits.ReadUIntBE(r, 24); err != nil {
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return
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}
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// max bitrate
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if maxBitrate, err = bits.ReadUIntBE(r, 32); err != nil {
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return
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}
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// avg bitrate
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if avgBitrate, err = bits.ReadUIntBE(r, 32); err != nil {
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return
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}
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if debugReader {
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println("readDecConfDesc:", objectId, streamType, bufSize, maxBitrate, avgBitrate)
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}
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if decConfig, err = readDescByTag(r, MP4DecSpecificDescrTag); err != nil {
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return
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}
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return
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}
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// copied from libavformat/movenc.c mov_write_esds_tag()
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func writeDecConfDesc(w io.Writer, objectId uint, streamType uint, decConfig []byte) (err error) {
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// objectId
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if err = bits.WriteUIntBE(w, objectId, 8); err != nil {
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return
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}
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// streamType
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if err = bits.WriteUIntBE(w, streamType, 8); err != nil {
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return
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}
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// buffer size db
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if err = bits.WriteUIntBE(w, 0, 24); err != nil {
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return
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}
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// max bitrate
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if err = bits.WriteUIntBE(w, 200000, 32); err != nil {
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return
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}
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// avg bitrate
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if err = bits.WriteUIntBE(w, 0, 32); err != nil {
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return
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}
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if err = writeDesc(w, MP4DecSpecificDescrTag, decConfig); err != nil {
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return
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}
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return
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}
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// copied from libavformat/mov.c ff_mov_read_esds()
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func ReadElemStreamDesc(r io.Reader) (decConfig []byte, err error) {
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if debugReader {
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println("ReadElemStreamDesc: start")
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}
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var data []byte
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if data, err = readDescByTag(r, MP4ESDescrTag); err != nil {
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return
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}
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r = bytes.NewReader(data)
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if err = readESDesc(r); err != nil {
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return
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}
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if data, err = readDescByTag(r, MP4DecConfigDescrTag); err != nil {
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return
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}
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r = bytes.NewReader(data)
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if decConfig, err = readDecConfDesc(r); err != nil {
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return
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}
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if debugReader {
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println("ReadElemStreamDesc: end")
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}
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return
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}
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func ReadElemStreamDescAAC(r io.Reader) (config MPEG4AudioConfig, err error) {
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var data []byte
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if data, err = ReadElemStreamDesc(r); err != nil {
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return
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}
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if debugReader {
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println("decConfig: ", len(data))
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}
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if config, err = ReadMPEG4AudioConfig(bytes.NewReader(data)); err != nil {
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return
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}
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return
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}
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func WriteElemStreamDescAAC(w io.Writer, config MPEG4AudioConfig, trackId uint) (err error) {
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// MP4ESDescrTag(ESDesc MP4DecConfigDescrTag(objectId streamType bufSize avgBitrate MP4DecSpecificDescrTag(decConfig)))
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buf := &bytes.Buffer{}
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WriteMPEG4AudioConfig(buf, config)
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data := buf.Bytes()
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buf = &bytes.Buffer{}
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// 0x40 = ObjectType AAC
|
|
// 0x15 = Audiostream
|
|
writeDecConfDesc(buf, 0x40, 0x15, data)
|
|
data = buf.Bytes()
|
|
|
|
buf = &bytes.Buffer{}
|
|
writeDesc(buf, MP4DecConfigDescrTag, data) // 4
|
|
data = buf.Bytes()
|
|
|
|
buf = &bytes.Buffer{}
|
|
writeESDesc(buf, trackId)
|
|
buf.Write(data)
|
|
writeDesc(buf, 0x06, []byte{0x02})
|
|
data = buf.Bytes()
|
|
|
|
buf = &bytes.Buffer{}
|
|
writeDesc(buf, MP4ESDescrTag, data) // 3
|
|
data = buf.Bytes()
|
|
|
|
if _, err = w.Write(data); err != nil {
|
|
return
|
|
}
|
|
return
|
|
}
|