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mp4-generator.ts
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/**
* Generate MP4 Box
*/
import { appendUint8Array } from '../utils/mp4-tools';
import type { DemuxedAudioTrack } from '../types/demuxer';
type HdlrTypes = {
video: Uint8Array;
audio: Uint8Array;
};
const UINT32_MAX = Math.pow(2, 32) - 1;
class MP4 {
public static types: Record<string, number[]>;
private static HDLR_TYPES: HdlrTypes;
private static STTS: Uint8Array;
private static STSC: Uint8Array;
private static STCO: Uint8Array;
private static STSZ: Uint8Array;
private static VMHD: Uint8Array;
private static SMHD: Uint8Array;
private static STSD: Uint8Array;
private static FTYP: Uint8Array;
private static DINF: Uint8Array;
static init() {
MP4.types = {
avc1: [], // codingname
avcC: [],
hvc1: [],
hvcC: [],
btrt: [],
dinf: [],
dref: [],
esds: [],
ftyp: [],
hdlr: [],
mdat: [],
mdhd: [],
mdia: [],
mfhd: [],
minf: [],
moof: [],
moov: [],
mp4a: [],
'.mp3': [],
dac3: [],
'ac-3': [],
mvex: [],
mvhd: [],
pasp: [],
sdtp: [],
stbl: [],
stco: [],
stsc: [],
stsd: [],
stsz: [],
stts: [],
tfdt: [],
tfhd: [],
traf: [],
trak: [],
trun: [],
trex: [],
tkhd: [],
vmhd: [],
smhd: [],
};
let i: string;
for (i in MP4.types) {
if (MP4.types.hasOwnProperty(i)) {
MP4.types[i] = [
i.charCodeAt(0),
i.charCodeAt(1),
i.charCodeAt(2),
i.charCodeAt(3),
];
}
}
const videoHdlr = new Uint8Array([
0x00, // version 0
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x00, // pre_defined
0x76,
0x69,
0x64,
0x65, // handler_type: 'vide'
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x00,
0x00,
0x00, // reserved
0x56,
0x69,
0x64,
0x65,
0x6f,
0x48,
0x61,
0x6e,
0x64,
0x6c,
0x65,
0x72,
0x00, // name: 'VideoHandler'
]);
const audioHdlr = new Uint8Array([
0x00, // version 0
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x00, // pre_defined
0x73,
0x6f,
0x75,
0x6e, // handler_type: 'soun'
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x00,
0x00,
0x00, // reserved
0x53,
0x6f,
0x75,
0x6e,
0x64,
0x48,
0x61,
0x6e,
0x64,
0x6c,
0x65,
0x72,
0x00, // name: 'SoundHandler'
]);
MP4.HDLR_TYPES = {
video: videoHdlr,
audio: audioHdlr,
};
const dref = new Uint8Array([
0x00, // version 0
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x01, // entry_count
0x00,
0x00,
0x00,
0x0c, // entry_size
0x75,
0x72,
0x6c,
0x20, // 'url' type
0x00, // version 0
0x00,
0x00,
0x01, // entry_flags
]);
const stco = new Uint8Array([
0x00, // version
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x00, // entry_count
]);
MP4.STTS = MP4.STSC = MP4.STCO = stco;
MP4.STSZ = new Uint8Array([
0x00, // version
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x00, // sample_size
0x00,
0x00,
0x00,
0x00, // sample_count
]);
MP4.VMHD = new Uint8Array([
0x00, // version
0x00,
0x00,
0x01, // flags
0x00,
0x00, // graphicsmode
0x00,
0x00,
0x00,
0x00,
0x00,
0x00, // opcolor
]);
MP4.SMHD = new Uint8Array([
0x00, // version
0x00,
0x00,
0x00, // flags
0x00,
0x00, // balance
0x00,
0x00, // reserved
]);
MP4.STSD = new Uint8Array([
0x00, // version 0
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x01,
]); // entry_count
const majorBrand = new Uint8Array([105, 115, 111, 109]); // isom
const avc1Brand = new Uint8Array([97, 118, 99, 49]); // avc1
const minorVersion = new Uint8Array([0, 0, 0, 1]);
MP4.FTYP = MP4.box(
MP4.types.ftyp,
majorBrand,
minorVersion,
majorBrand,
avc1Brand,
);
MP4.DINF = MP4.box(MP4.types.dinf, MP4.box(MP4.types.dref, dref));
}
static box(type, ...payload: Uint8Array[]) {
let size = 8;
let i = payload.length;
const len = i;
// calculate the total size we need to allocate
while (i--) {
size += payload[i].byteLength;
}
const result = new Uint8Array(size);
result[0] = (size >> 24) & 0xff;
result[1] = (size >> 16) & 0xff;
result[2] = (size >> 8) & 0xff;
result[3] = size & 0xff;
result.set(type, 4);
// copy the payload into the result
for (i = 0, size = 8; i < len; i++) {
// copy payload[i] array @ offset size
result.set(payload[i], size);
size += payload[i].byteLength;
}
return result;
}
static hdlr(type) {
return MP4.box(MP4.types.hdlr, MP4.HDLR_TYPES[type]);
}
static mdat(data) {
return MP4.box(MP4.types.mdat, data);
}
static mdhd(timescale, duration) {
duration *= timescale;
const upperWordDuration = Math.floor(duration / (UINT32_MAX + 1));
const lowerWordDuration = Math.floor(duration % (UINT32_MAX + 1));
return MP4.box(
MP4.types.mdhd,
new Uint8Array([
0x01, // version 1
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x02, // creation_time
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x03, // modification_time
(timescale >> 24) & 0xff,
(timescale >> 16) & 0xff,
(timescale >> 8) & 0xff,
timescale & 0xff, // timescale
upperWordDuration >> 24,
(upperWordDuration >> 16) & 0xff,
(upperWordDuration >> 8) & 0xff,
upperWordDuration & 0xff,
lowerWordDuration >> 24,
(lowerWordDuration >> 16) & 0xff,
(lowerWordDuration >> 8) & 0xff,
lowerWordDuration & 0xff,
0x55,
0xc4, // 'und' language (undetermined)
0x00,
0x00,
]),
);
}
static mdia(track) {
return MP4.box(
MP4.types.mdia,
MP4.mdhd(track.timescale, track.duration),
MP4.hdlr(track.type),
MP4.minf(track),
);
}
static mfhd(sequenceNumber) {
return MP4.box(
MP4.types.mfhd,
new Uint8Array([
0x00,
0x00,
0x00,
0x00, // flags
sequenceNumber >> 24,
(sequenceNumber >> 16) & 0xff,
(sequenceNumber >> 8) & 0xff,
sequenceNumber & 0xff, // sequence_number
]),
);
}
static minf(track) {
if (track.type === 'audio') {
return MP4.box(
MP4.types.minf,
MP4.box(MP4.types.smhd, MP4.SMHD),
MP4.DINF,
MP4.stbl(track),
);
} else {
return MP4.box(
MP4.types.minf,
MP4.box(MP4.types.vmhd, MP4.VMHD),
MP4.DINF,
MP4.stbl(track),
);
}
}
static moof(sn, baseMediaDecodeTime, track) {
return MP4.box(
MP4.types.moof,
MP4.mfhd(sn),
MP4.traf(track, baseMediaDecodeTime),
);
}
static moov(tracks) {
let i = tracks.length;
const boxes: Uint8Array[] = [];
while (i--) {
boxes[i] = MP4.trak(tracks[i]);
}
return MP4.box.apply(
null,
[MP4.types.moov, MP4.mvhd(tracks[0].timescale, tracks[0].duration)]
.concat(boxes)
.concat(MP4.mvex(tracks)),
);
}
static mvex(tracks) {
let i = tracks.length;
const boxes: Uint8Array[] = [];
while (i--) {
boxes[i] = MP4.trex(tracks[i]);
}
return MP4.box.apply(null, [MP4.types.mvex, ...boxes]);
}
static mvhd(timescale, duration) {
duration *= timescale;
const upperWordDuration = Math.floor(duration / (UINT32_MAX + 1));
const lowerWordDuration = Math.floor(duration % (UINT32_MAX + 1));
const bytes = new Uint8Array([
0x01, // version 1
0x00,
0x00,
0x00, // flags
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x02, // creation_time
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x03, // modification_time
(timescale >> 24) & 0xff,
(timescale >> 16) & 0xff,
(timescale >> 8) & 0xff,
timescale & 0xff, // timescale
upperWordDuration >> 24,
(upperWordDuration >> 16) & 0xff,
(upperWordDuration >> 8) & 0xff,
upperWordDuration & 0xff,
lowerWordDuration >> 24,
(lowerWordDuration >> 16) & 0xff,
(lowerWordDuration >> 8) & 0xff,
lowerWordDuration & 0xff,
0x00,
0x01,
0x00,
0x00, // 1.0 rate
0x01,
0x00, // 1.0 volume
0x00,
0x00, // reserved
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x01,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x01,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x40,
0x00,
0x00,
0x00, // transformation: unity matrix
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00, // pre_defined
0xff,
0xff,
0xff,
0xff, // next_track_ID
]);
return MP4.box(MP4.types.mvhd, bytes);
}
static sdtp(track) {
const samples = track.samples || [];
const bytes = new Uint8Array(4 + samples.length);
let i;
let flags;
// leave the full box header (4 bytes) all zero
// write the sample table
for (i = 0; i < samples.length; i++) {
flags = samples[i].flags;
bytes[i + 4] =
(flags.dependsOn << 4) |
(flags.isDependedOn << 2) |
flags.hasRedundancy;
}
return MP4.box(MP4.types.sdtp, bytes);
}
static stbl(track) {
return MP4.box(
MP4.types.stbl,
MP4.stsd(track),
MP4.box(MP4.types.stts, MP4.STTS),
MP4.box(MP4.types.stsc, MP4.STSC),
MP4.box(MP4.types.stsz, MP4.STSZ),
MP4.box(MP4.types.stco, MP4.STCO),
);
}
static avc1(track) {
let sps: number[] = [];
let pps: number[] = [];
let i;
let data;
let len;
// assemble the SPSs
for (i = 0; i < track.sps.length; i++) {
data = track.sps[i];
len = data.byteLength;
sps.push((len >>> 8) & 0xff);
sps.push(len & 0xff);
// SPS
sps = sps.concat(Array.prototype.slice.call(data));
}
// assemble the PPSs
for (i = 0; i < track.pps.length; i++) {
data = track.pps[i];
len = data.byteLength;
pps.push((len >>> 8) & 0xff);
pps.push(len & 0xff);
pps = pps.concat(Array.prototype.slice.call(data));
}
const avcc = MP4.box(
MP4.types.avcC,
new Uint8Array(
[
0x01, // version
sps[3], // profile
sps[4], // profile compat
sps[5], // level
0xfc | 3, // lengthSizeMinusOne, hard-coded to 4 bytes
0xe0 | track.sps.length, // 3bit reserved (111) + numOfSequenceParameterSets
]
.concat(sps)
.concat([
track.pps.length, // numOfPictureParameterSets
])
.concat(pps),
),
); // "PPS"
const width = track.width;
const height = track.height;
const hSpacing = track.pixelRatio[0];
const vSpacing = track.pixelRatio[1];
return MP4.box(
MP4.types.avc1,
new Uint8Array([
0x00,
0x00,
0x00, // reserved
0x00,
0x00,
0x00, // reserved
0x00,
0x01, // data_reference_index
0x00,
0x00, // pre_defined
0x00,
0x00, // reserved
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00, // pre_defined
(width >> 8) & 0xff,
width & 0xff, // width
(height >> 8) & 0xff,
height & 0xff, // height
0x00,
0x48,
0x00,
0x00, // horizresolution
0x00,
0x48,
0x00,
0x00, // vertresolution
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x01, // frame_count
0x12,
0x64,
0x61,
0x69,
0x6c, // dailymotion/hls.js
0x79,
0x6d,
0x6f,
0x74,
0x69,
0x6f,
0x6e,
0x2f,
0x68,
0x6c,
0x73,
0x2e,
0x6a,
0x73,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00, // compressorname
0x00,
0x18, // depth = 24
0x11,
0x11,
]), // pre_defined = -1
avcc,
MP4.box(
MP4.types.btrt,
new Uint8Array([
0x00,
0x1c,
0x9c,
0x80, // bufferSizeDB
0x00,
0x2d,
0xc6,
0xc0, // maxBitrate
0x00,
0x2d,
0xc6,
0xc0,
]),
), // avgBitrate
MP4.box(
MP4.types.pasp,
new Uint8Array([
hSpacing >> 24, // hSpacing
(hSpacing >> 16) & 0xff,
(hSpacing >> 8) & 0xff,
hSpacing & 0xff,
vSpacing >> 24, // vSpacing
(vSpacing >> 16) & 0xff,
(vSpacing >> 8) & 0xff,
vSpacing & 0xff,
]),
),
);
}
static esds(track: DemuxedAudioTrack) {
const config = track.config as [number, number];
return new Uint8Array([
0x00, // version 0
0x00,
0x00,
0x00, // flags
0x03, // descriptor_type
0x19, // length
0x00,
0x01, // es_id
0x00, // stream_priority
0x04, // descriptor_type
0x11, // length
0x40, // codec : mpeg4_audio
0x15, // stream_type
0x00,
0x00,
0x00, // buffer_size
0x00,
0x00,
0x00,
0x00, // maxBitrate
0x00,
0x00,
0x00,
0x00, // avgBitrate
0x05, // descriptor_type
0x02, // length
...config,
0x06,
0x01,
0x02, // GASpecificConfig)); // length + audio config descriptor
]);
}
static audioStsd(track) {
const samplerate = track.samplerate;
return new Uint8Array([
0x00,
0x00,
0x00, // reserved
0x00,
0x00,
0x00, // reserved
0x00,
0x01, // data_reference_index
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
track.channelCount, // channelcount
0x00,
0x10, // sampleSize:16bits
0x00,
0x00,
0x00,
0x00, // reserved2
(samplerate >> 8) & 0xff,
samplerate & 0xff, //
0x00,
0x00,
]);
}
static mp4a(track) {
return MP4.box(
MP4.types.mp4a,
MP4.audioStsd(track),
MP4.box(MP4.types.esds, MP4.esds(track)),
);
}
static mp3(track) {
return MP4.box(MP4.types['.mp3'], MP4.audioStsd(track));
}
static ac3(track) {
return MP4.box(
MP4.types['ac-3'],
MP4.audioStsd(track),
MP4.box(MP4.types.dac3, track.config),
);
}
static stsd(track) {
if (track.type === 'audio') {
if (track.segmentCodec === 'mp3' && track.codec === 'mp3') {
return MP4.box(MP4.types.stsd, MP4.STSD, MP4.mp3(track));
}
if (track.segmentCodec === 'ac3') {
return MP4.box(MP4.types.stsd, MP4.STSD, MP4.ac3(track));
}
return MP4.box(MP4.types.stsd, MP4.STSD, MP4.mp4a(track));
} else if (track.segmentCodec === 'avc') {
return MP4.box(MP4.types.stsd, MP4.STSD, MP4.avc1(track));
} else {
return MP4.box(MP4.types.stsd, MP4.STSD, MP4.hvc1(track));
}
}
static tkhd(track) {
const id = track.id;
const duration = track.duration * track.timescale;
const width = track.width;
const height = track.height;
const upperWordDuration = Math.floor(duration / (UINT32_MAX + 1));
const lowerWordDuration = Math.floor(duration % (UINT32_MAX + 1));
return MP4.box(
MP4.types.tkhd,
new Uint8Array([
0x01, // version 1
0x00,
0x00,
0x07, // flags
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x02, // creation_time
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x03, // modification_time
(id >> 24) & 0xff,
(id >> 16) & 0xff,
(id >> 8) & 0xff,
id & 0xff, // track_ID
0x00,
0x00,
0x00,
0x00, // reserved
upperWordDuration >> 24,
(upperWordDuration >> 16) & 0xff,
(upperWordDuration >> 8) & 0xff,
upperWordDuration & 0xff,
lowerWordDuration >> 24,
(lowerWordDuration >> 16) & 0xff,
(lowerWordDuration >> 8) & 0xff,
lowerWordDuration & 0xff,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00, // reserved
0x00,
0x00, // layer
0x00,
0x00, // alternate_group
0x00,
0x00, // non-audio track volume
0x00,
0x00, // reserved
0x00,
0x01,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x01,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x40,
0x00,
0x00,
0x00, // transformation: unity matrix
(width >> 8) & 0xff,
width & 0xff,
0x00,
0x00, // width
(height >> 8) & 0xff,
height & 0xff,
0x00,
0x00, // height
]),
);
}
static traf(track, baseMediaDecodeTime) {
const sampleDependencyTable = MP4.sdtp(track);
const id = track.id;
const upperWordBaseMediaDecodeTime = Math.floor(
baseMediaDecodeTime / (UINT32_MAX + 1),
);
const lowerWordBaseMediaDecodeTime = Math.floor(
baseMediaDecodeTime % (UINT32_MAX + 1),
);
return MP4.box(
MP4.types.traf,
MP4.box(
MP4.types.tfhd,
new Uint8Array([
0x00, // version 0
0x00,
0x00,
0x00, // flags
id >> 24,
(id >> 16) & 0xff,
(id >> 8) & 0xff,
id & 0xff, // track_ID
]),
),
MP4.box(
MP4.types.tfdt,
new Uint8Array([
0x01, // version 1
0x00,
0x00,
0x00, // flags
upperWordBaseMediaDecodeTime >> 24,
(upperWordBaseMediaDecodeTime >> 16) & 0xff,
(upperWordBaseMediaDecodeTime >> 8) & 0xff,
upperWordBaseMediaDecodeTime & 0xff,
lowerWordBaseMediaDecodeTime >> 24,
(lowerWordBaseMediaDecodeTime >> 16) & 0xff,