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MPEG-TS probe improvement #5186

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merged 1 commit into from
Feb 1, 2023
Merged

MPEG-TS probe improvement #5186

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41 changes: 30 additions & 11 deletions src/demux/tsdemuxer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -98,14 +98,24 @@ class TSDemuxer implements Demuxer {
return syncOffset !== -1;
}

static syncOffset(data: Uint8Array) {
static syncOffset(data: Uint8Array): number {
const scanwindow =
Math.min(PACKET_LENGTH * 5, data.length - PACKET_LENGTH * 2) + 1;
Math.min(PACKET_LENGTH * 5, data.length - PACKET_LENGTH) + 1;
let i = 0;
while (i < scanwindow) {
// a TS init segment should contain at least 2 TS packets: PAT and PMT, each starting with 0x47
if (data[i] === 0x47 && data[i + PACKET_LENGTH] === 0x47) {
return i;
let foundPat = false;
for (let j = 0; j < scanwindow; j += PACKET_LENGTH) {
if (data[j] === 0x47) {
if (!foundPat && parsePID(data, j) === 0) {
foundPat = true;
}
if (foundPat && j + PACKET_LENGTH > scanwindow) {
return i;
}
} else {
break;
}
}
i++;
}
Expand Down Expand Up @@ -245,8 +255,7 @@ class TSDemuxer implements Demuxer {
for (let start = syncOffset; start < len; start += PACKET_LENGTH) {
if (data[start] === 0x47) {
const stt = !!(data[start + 1] & 0x40);
// pid is a 13-bit field starting at the last bit of TS[1]
const pid = ((data[start + 1] & 0x1f) << 8) + data[start + 2];
const pid = parsePID(data, start);
const atf = (data[start + 3] & 0x30) >> 4;

// if an adaption field is present, its length is specified by the fifth byte of the TS packet header.
Expand Down Expand Up @@ -312,6 +321,7 @@ class TSDemuxer implements Demuxer {
}

pmtId = this._pmtId = parsePAT(data, offset);
// logger.log('PMT PID:' + this._pmtId);
break;
case pmtId: {
if (stt) {
Expand Down Expand Up @@ -355,7 +365,7 @@ class TSDemuxer implements Demuxer {
pmtParsed = this.pmtParsed = true;
break;
}
case 17:
case 0x11:
case 0x1fff:
break;
default:
Expand Down Expand Up @@ -988,13 +998,22 @@ function createAVCSample(
};
}

function parsePAT(data, offset) {
function parsePID(data: Uint8Array, offset: number): number {
// pid is a 13-bit field starting at the last bit of TS[1]
return ((data[offset + 1] & 0x1f) << 8) + data[offset + 2];
}

function parsePAT(data: Uint8Array, offset: number): number {
// skip the PSI header and parse the first PMT entry
return ((data[offset + 10] & 0x1f) << 8) | data[offset + 11];
// logger.log('PMT PID:' + this._pmtId);
}

function parsePMT(data, offset, typeSupported, isSampleAes) {
function parsePMT(
data: Uint8Array,
offset: number,
typeSupported: TypeSupported,
isSampleAes: boolean
) {
const result = { audio: -1, avc: -1, id3: -1, segmentCodec: 'aac' };
const sectionLength = ((data[offset + 1] & 0x0f) << 8) | data[offset + 2];
const tableEnd = offset + 3 + sectionLength - 4;
Expand All @@ -1005,7 +1024,7 @@ function parsePMT(data, offset, typeSupported, isSampleAes) {
// advance the offset to the first entry in the mapping table
offset += 12 + programInfoLength;
while (offset < tableEnd) {
const pid = ((data[offset + 1] & 0x1f) << 8) | data[offset + 2];
const pid = parsePID(data, offset);
switch (data[offset]) {
case 0xcf: // SAMPLE-AES AAC
if (!isSampleAes) {
Expand Down