Accented characters being displayed twice in 607/608 stream

[mamaddox]

What version of Hls.js are you using?

1.4.10 (But tested on 1.5.8 as well)

What browser (including version) are you using?

Chrome 124.0.6367.62

What OS (including version) are you using?

macOS 12.7.2

Test stream

https://cpac-vod.cdn.vustreams.com/cpac/vod/b69d4bce-1c39-4fb4-9b1e-ad016553bb8b/b69d4bce-1c39-4fb4-9b1e-ad016553bb8b_nodrm_3a7ee1c0-beb8-41eb-8623-d00096e3de23.ism/.m3u8

Configuration

{
  "debug": true,
  "enableWorker": true,
  "lowLatencyMode": true,
  "backBufferLength": 90
}

Additional player setup steps

No response

Checklist

• The issue observed is not already reported by searching on Github under https://github.com/video-dev/hls.js/issues
• The issue occurs in the stable client (latest release) on https://hlsjs.video-dev.org/demo and not just on my page
• The issue occurs in the latest client (main branch) on https://hlsjs-dev.video-dev.org/demo and not just on my page
• The stream has correct Access-Control-Allow-Origin headers (CORS)
• There are no network errors such as 404s in the browser console when trying to play the stream

Steps to reproduce

1. Load the test stream
2. Turn on captions when they become available
3. See that some accented characters are being duplicated

Expected behaviour

Accented characters should be displayed only once

What actually happened?

Certain accented characters are displaying twice

Did a little investigation in the cea-608-parser.ts, and it looks like characters 0x80-0x8f are the special characters that are being duplicated:

hls.js/src/utils/cea-608-parser.ts

Lines 59 to 74 in d97009e

	0x80: 0xae, // Registered symbol (R)
	0x81: 0xb0, // degree sign
	0x82: 0xbd, // 1/2 symbol
	0x83: 0xbf, // Inverted (open) question mark
	0x84: 0x2122, // Trademark symbol (TM)
	0x85: 0xa2, // Cents symbol
	0x86: 0xa3, // Pounds sterling
	0x87: 0x266a, // Music 8'th note
	0x88: 0xe0, // lowercase a, grave accent
	0x89: 0x20, // transparent space (regular)
	0x8a: 0xe8, // lowercase e, grave accent
	0x8b: 0xe2, // lowercase a, circumflex accent
	0x8c: 0xea, // lowercase e, circumflex accent
	0x8d: 0xee, // lowercase i, circumflex accent
	0x8e: 0xf4, // lowercase o, circumflex accent
	0x8f: 0xfb, // lowercase u, circumflex accent

Not sure if it's related to the insertChar function.

hls.js/src/utils/cea-608-parser.ts

Lines 448 to 470 in d97009e

	insertChar(byte: number) {
	if (byte >= 0x90) {
	// Extended char
	this.backSpace();
	}
	const char = getCharForByte(byte);
	if (this.pos >= NR_COLS) {
	this.logger.log(
	VerboseLevel.ERROR,
	() =>
	'Cannot insert ' +
	byte.toString(16) +
	' (' +
	char +
	') at position ' +
	this.pos +
	'. Skipping it!',
	);
	return;
	}
	this.chars[this.pos].setChar(char, this.currPenState);
	this.moveCursor(1);
	}

Console output

[log] > [stream-controller]: media seeking to 226.834, state: ENDED
base-stream-controller.ts:1639 [log] > [stream-controller]: Reset loading state
base-stream-controller.ts:1781 [log] > [stream-controller]: ENDED->IDLE
base-stream-controller.ts:241 [log] > [audio-stream-controller]: media seeking to 226.834, state: ENDED
base-stream-controller.ts:1639 [log] > [audio-stream-controller]: Reset loading state
base-stream-controller.ts:1781 [log] > [audio-stream-controller]: ENDED->IDLE
base-stream-controller.ts:241 [log] > [subtitle-stream-controller]: media seeking to 226.834, state: IDLE
buffer-controller.ts:645 [log] > [buffer-controller] Queueing mediaSource.endOfStream()
base-stream-controller.ts:1781 [log] > [stream-controller]: IDLE->ENDED
buffer-controller.ts:656 [log] > [buffer-controller] Could not call mediaSource.endOfStream(). mediaSource.readyState: ended
buffer-controller.ts:645 [log] > [buffer-controller] Queueing mediaSource.endOfStream()
base-stream-controller.ts:1781 [log] > [audio-stream-controller]: IDLE->ENDED
buffer-controller.ts:656 [log] > [buffer-controller] Could not call mediaSource.endOfStream(). mediaSource.readyState: ended
stream-controller.ts:556 [log] > [stream-controller]: Media seeked to 226.834

Chrome media internals output

No response