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[YT seek] Only request header data and stop parsing header after reaching the desired cue

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This commit is contained in:
absidue 2022-01-05 18:48:42 +01:00
parent e5707f049b
commit ce45f3ca62
3 changed files with 48 additions and 18 deletions
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34
play-dl/YouTube/classes/SeekStream.ts
View File

@ -29,6 +29,10 @@ export class SeekStream {
* Calculate per second bytes by using contentLength (Total bytes) / Duration (in seconds)
*/
private per_sec_bytes: number;
/**
* Length of the header in bytes
*/
private header_length: number;
/**
* Total length of audio file in bytes
*/
@ -57,12 +61,20 @@ export class SeekStream {
* @param url Audio Endpoint url.
* @param type Type of Stream
* @param duration Duration of audio playback [ in seconds ]
* @param headerLength Length of the header in bytes.
* @param contentLength Total length of Audio file in bytes.
* @param video_url YouTube video url.
* @param options Options provided to stream function.
*/
constructor(url: string, duration: number, contentLength: number, video_url: string, options: StreamOptions) {
this.stream = new WebmSeeker({
constructor(
url: string,
duration: number,
headerLength: number,
contentLength: number,
video_url: string,
options: StreamOptions
) {
this.stream = new WebmSeeker(options.seek!, {
highWaterMark: 5 * 1000 * 1000,
readableObjectMode: true
});
@ -72,6 +84,7 @@ export class SeekStream {
this.bytes_count = 0;
this.video_url = video_url;
this.per_sec_bytes = Math.ceil(contentLength / duration);
this.header_length = headerLength;
this.content_length = contentLength;
this.request = null;
this.timer = new Timer(() => {
@ -82,21 +95,20 @@ export class SeekStream {
this.timer.destroy();
this.cleanup();
});
this.seek(options.seek!);
this.seek();
}
/**
* **INTERNAL Function**
*
* Uses stream functions to parse Webm Head and gets Offset byte to seek to.
* @param sec No of seconds to seek to
* @returns Nothing
*/
private async seek(sec: number): Promise<void> {
private async seek(): Promise<void> {
const parse = await new Promise(async (res, rej) => {
if (!this.stream.headerparsed) {
const stream = await request_stream(this.url, {
headers: {
range: `bytes=0-`
range: `bytes=0-${this.header_length}`
}
}).catch((err: Error) => err);
@ -111,6 +123,12 @@ export class SeekStream {
this.request = stream;
stream.pipe(this.stream, { end: false });
// headComplete should always be called, leaving this here just in case
stream.once('end', () => {
this.stream.state = WebmSeekerState.READING_DATA;
res('');
});
this.stream.once('headComplete', () => {
stream.unpipe(this.stream);
stream.destroy();
@ -128,9 +146,9 @@ export class SeekStream {
} else if (parse === 400) {
await this.retry();
this.timer.reuse();
return this.seek(sec);
return this.seek();
}
const bytes = this.stream.seek(sec);
const bytes = this.stream.seek();
if (bytes instanceof Error) {
this.stream.emit('error', bytes);
this.bytes_count = 0;

31
play-dl/YouTube/classes/WebmSeeker.ts
View File

@ -31,8 +31,11 @@ export class WebmSeeker extends Duplex {
seekfound: boolean;
private data_size: number;
private data_length: number;
private sec: number;
private time: number;
private foundCue: boolean;
constructor(options: WebmSeekerOptions) {
constructor(sec: number, options: WebmSeekerOptions) {
super(options);
this.state = WebmSeekerState.READING_HEAD;
this.cursor = 0;
@ -42,6 +45,9 @@ export class WebmSeeker extends Duplex {
this.seekfound = false;
this.data_length = 0;
this.data_size = 0;
this.sec = sec;
this.time = Math.floor(sec / 10) * 10;
this.foundCue = false;
}
private get vint_length(): number {
@ -71,17 +77,16 @@ export class WebmSeeker extends Duplex {
_read() {}
seek(sec: number): Error | number {
seek(): Error | number {
let clusterlength = 0,
position = 0;
const time = Math.floor(sec / 10) * 10;
let time_left = (sec - time) * 1000 || 0;
let time_left = (this.sec - this.time) * 1000 || 0;
time_left = Math.round(time_left / 20) * 20;
if (!this.header.segment.cues) return new Error('Failed to Parse Cues');
for (let i = 0; i < this.header.segment.cues.length; i++) {
const data = this.header.segment.cues[i];
if (Math.floor((data.time as number) / 1000) === time) {
if (Math.floor((data.time as number) / 1000) === this.time) {
position = data.position as number;
clusterlength = this.header.segment.cues[i + 1].position! - position - 1;
break;
@ -130,11 +135,6 @@ export class WebmSeeker extends Duplex {
if (ebmlID.name === 'ebml') this.headfound = true;
else return new Error('Failed to find EBML ID at start of stream.');
}
if (ebmlID.name === 'cluster') {
this.emit('headComplete');
this.cursor = this.chunk.length;
break;
}
const data = this.chunk.slice(
this.cursor + this.data_size,
this.cursor + this.data_size + this.data_length
@ -142,6 +142,17 @@ export class WebmSeeker extends Duplex {
const parse = this.header.parse(ebmlID, data);
if (parse instanceof Error) return parse;
// stop parsing the header once we have found the correct cue
if (ebmlID.name === 'cueClusterPosition') {
if (this.foundCue) {
this.emit('headComplete');
this.cursor = this.chunk.length;
break;
} else if (this.time === (this.header.segment.cues!.at(-1)!.time as number) / 1000) {
this.foundCue = true;
}
}
if (ebmlID.type === DataType.master) {
this.cursor += this.data_size;
continue;

1
play-dl/YouTube/stream.ts
View File

@ -92,6 +92,7 @@ export async function stream_from_info(
return new SeekStream(
final[0].url,
info.video_details.durationInSec,
final[0].indexRange.end,
Number(final[0].contentLength),
info.video_details.url,
options