1703444 - [webvtt] NOTE as subtitle in Firefox 87.0

Status: RESOLVED FIXED

(Core :: Audio/Video: Playback, defect, P3)

Description

[github]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0

Steps to reproduce:

1. Create a vtt file with this subtitle:
   00:00.000 --> 00:02.000
   NOTE A
2. Put it in a "track" element and start a video with this subtitle file.

Actual results:

Firefox 87 doesn't show a subtitle.

Expected results:

Firefox should show "NOTE A" as subtitle.
Chromium 89.0 shows this.
Also see here: https://stackoverflow.com/questions/66903928/webvtt-escape-note-in-subtitle-for-firefox-87-0

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Audio/Video: Playback' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 2

[Jon Bauman [:jbauman:]]

Thanks for the bug report!

Per https://www.w3.org/TR/webvtt1/#introduction-comments

Comments are just blocks that are preceded by a blank line

So, it does seem like Firefox should render a line starting with NOTE when it's in a cue position like the example.

As a workaround, you can precede the NOTE with a space, and Firefox appears to render it.

Comment 3

[Alastor Wu [:alwu]]

Yes, this is Firefox bug, currently we would skip all line starting with NOTE [1] and we should handle the NOTE in a better way.

[1] https://searchfox.org/mozilla-central/rev/62135a96327f42fd1ccf8a04feb62be04b102195/dom/media/webvtt/vtt.jsm#1372-1374

Comment 4

[Alastor Wu [:alwu]]

Attachment: Bug 1703444 - part1 : comment block should be preceded by a blank line.

Comment 5

[Alastor Wu [:alwu]]

Attachment: Bug 1703444 - part2 : add more debug log.

Depends on D111300

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b5a9076a78b5
part1 : comment block should be preceded by a blank line. r=jbauman
https://hg.mozilla.org/integration/autoland/rev/200e93289ab1
part2 : add more debug log. r=jbauman

Comment 7

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/28419 for changes under testing/web-platform/tests

Comment 8

[Cristian Brindusan [:cbrindusan]]

Backed out 2 changesets (bug 1703444) for causing xpcshell failures at test_parser.js.
https://hg.mozilla.org/integration/autoland/rev/2f1e4b2f76b16861e311e716e390da55b84dd689

Push with failures:
https://treeherder.mozilla.org/jobs?repo=autoland&revision=200e93289ab15fe055dedfd6c54edd1491d7340f&selectedTaskRun=ANCtwc0eRAaJZ1Kib5MwlA.0

Failure log:
https://treeherder.mozilla.org/logviewer?job_id=335907796&repo=autoland&lineNumber=8713

Comment 9

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Upstream PR was closed without merging

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a3a331a5c7bf
part1 : comment block should be preceded by a blank line. r=jbauman
https://hg.mozilla.org/integration/autoland/rev/9e7725587bbf
part2 : add more debug log. r=jbauman

Comment 11

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/a3a331a5c7bf
https://hg.mozilla.org/mozilla-central/rev/9e7725587bbf

Comment 12

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot