Testing Video, Audio and Time Limits

Why it matters

When media or timing has a defect, content is not just harder to use, it is unavailable: a deaf learner cannot follow an uncaptioned lesson, a blind user misses the steps a demo only shows, a screen-reader user cannot hear their screen reader over audio that started on its own, and someone who types slowly with a switch device or a screen reader loses a half-finished form when the session expires. For a product this means support calls, lost sales and, where accessibility is required by law or contract, a compliance gap.

Most of these defects are also invisible to automated checkers. A scanner can see that a <track> element exists, but not whether the captions match the speech, name the speakers or keep pace with the video, and it will not wait 15 minutes for a session warning. This is manual work, and a tester who knows the criteria can raise most of it while the video is still a script.

Which media criteria apply: 1.2.1 to 1.2.5

Start by classifying each piece of media, because the criteria depend on what it contains and whether it is live. WCAG calls sound and moving pictures together synchronized media; a podcast is audio-only and a silent product animation is video-only.

Three alternatives appear in the criteria. Captions are synchronized text for the speech and for the non-speech sounds needed to understand the content, such as a doorbell, laughter or music, with the speaker identified; that is what separates them from dialogue-only subtitles, although some countries call both subtitles. Audio description is narration added to the soundtrack that describes important visual information the soundtrack does not already convey. An alternative for time-based media, called a full text alternative in this lesson, describes what is seen and heard in the correct order; a transcript with visual descriptions is the common form. It is not the same as the short text alternative (alt text) of an image.

• 1.2.1 Audio-only and Video-only (Prerecorded), Level A: a transcript for prerecorded audio; a full text alternative or an audio track with the same information for prerecorded silent video.
• 1.2.2 Captions (Prerecorded), A: captions for all prerecorded audio in synchronized media.
• 1.2.3 Audio Description or Media Alternative (Prerecorded), A: audio description of the video, or a full text alternative.
• 1.2.4 Captions (Live), AA: captions for live audio in synchronized media, such as a webinar or a live stream.
• 1.2.5 Audio Description (Prerecorded), AA: audio description is required; the text alternative that was enough for 1.2.3 no longer suffices. Where everything shown is already said in the audio, no description is needed.
• 1.2.1 to 1.2.3 exempt a media version of text that is already on the page when it is clearly labelled as such. Level AAA adds sign language, extended audio description, a full media alternative and live audio-only alternatives (1.2.6 to 1.2.9).

Testing caption and transcript quality

WCAG requires captions but sets no numeric accuracy target, so the expected result comes from the source: the script, or a careful listen. Watch the whole video with sound and captions on. Treat automatic captions as an unreviewed draft: they often mishear names, product terms and numbers, and rarely identify speakers or sounds. Captions usually come as a WebVTT file (.vtt), the format browsers load through the HTML <track> element: in it the <v> tag names the speaker, and by convention a sound is written in square brackets.

• Synchronization: each caption appears with its speech and leaves when the speaker stops. Check the start, the middle and the end, because a file timed for a different edit drifts away from the audio.
• Accuracy: words, names and numbers match the audio. Paste the script and the caption text, without the timing lines, into a text diff in word mode to see every difference at once.
• Speakers: when more than one person talks, or the speaker is off screen, the caption says who is speaking.
• Sound cues: meaningful sounds appear in square brackets, such as [alarm beeping] or [music stops].
• Arabic captions: lines read right to left. The browser takes each caption line's direction from its first strong character, the first letter with a fixed direction (Arabic or Latin; digits and punctuation do not count). A line that starts with a Latin brand name or an English term is therefore laid out left to right, with its full stop at the right end. Test such lines on purpose (a right-to-left mark, U+200F, at the start of the line fixes them), and check that the track is marked srclang="ar" and has a readable label in the captions menu.
• Transcripts: a link next to the player, and the full text with speaker names, sound cues and, for video, a description of what is shown.

WEBVTT

00:00:01.000 --> 00:00:04.200
<v Trainer>Open Orders and filter by status.

00:00:04.200 --> 00:00:05.500
[notification chime]

00:00:05.500 --> 00:00:09.000
<v Customer>Why is my order still pending?

00:00:09.000 --> 00:00:12.800
<v Trainer>Pending means the payment
has not been confirmed yet.

Try it: Text Diff Try it: Arabic Test Data Generator

Autoplay and the media player

1.4.2 Audio Control (A): if any audio on a page plays automatically for more than 3 seconds, there must be a way to pause or stop it, or to set its volume independently of the system volume. WCAG lists it among the criteria that apply to all content on a page, because a failure interferes with using anything else there. Browsers block some autoplay with sound, but their rules differ and they usually allow sound once the user has interacted with the site, so test with sound autoplay allowed in the browser's site settings, and again by opening the page after you have clicked elsewhere on the site.

The player itself must work without a mouse and make sense to a screen reader. The keyboard accessibility guide covers the method; for a player, check these points:

• Every control is reachable with Tab in a logical order, works with Enter or Space, and shows visible focus against the dark video (2.1.1, 2.4.3, 2.4.7).
• Seek and volume sliders move with the arrow keys and announce a useful value, such as "1 minute 20 seconds of 4 minutes", not "0.33".
• Buttons have names and states that update: Play becomes Pause, and Captions is announced as on or off (4.1.2).
• Focus can leave an embedded player, including a third-party iframe, with Tab and Shift+Tab, or with another key the page tells the user about (2.1.2 No Keyboard Trap), and Escape leaves full screen.
• Single-key shortcuts such as K or M work only while the player has focus, or can be turned off, or remapped to a combination with Ctrl or Alt (2.1.4 Character Key Shortcuts).

Time limits, session time-outs and carousels

2.2.1 Timing Adjustable (A) applies to each time limit the content sets: a session that ends after inactivity, a timed offer that holds a price or seats for 10 minutes, a form that must be finished in time. At least one option must hold: the user can turn the limit off beforehand; adjust it to at least ten times the default; or is warned before it expires, gets at least 20 seconds to extend it with a simple action such as pressing one key, and can extend it at least ten times. The exceptions are real-time events such as an auction where no alternative to the limit is possible, limits where more time would invalidate the activity (essential), and limits longer than 20 hours.

To test a 15-minute session without waiting, ask the developers to shorten it in the test environment. Then check that the warning appears in time, is announced by a screen reader, can be reached at once from the keyboard, and that extending really renews the server session, not only the visible counter. After expiry, 2.2.5 Re-authenticating (AAA) asks that the user can sign in again and continue without losing data; many teams treat that as good practice.

2.2.2 Pause, Stop, Hide (A), introduced in the visual accessibility guide for motion, also covers auto-updating content. Moving, blinking or scrolling content that starts automatically, lasts more than five seconds and sits beside other content needs a way to pause, stop or hide it; content that updates by itself, such as a news ticker or live scores, needs a way to pause, stop or hide it or to control how often it updates. Both parts make an exception for movement or updating that is essential to the activity.

• Carousel: a pause or stop control that works with the keyboard (2.2.2). The ARIA Authoring Practices carousel pattern places it first in the Tab order inside the carousel, before the rotating slides.
• Rotation stops when keyboard focus enters the carousel, and also while the mouse hovers over it, as the same pattern describes; stopping on hover alone is not enough, because keyboard and touch users cannot hover.
• Once stopped by focus or by the pause control, the carousel stays stopped until the user starts it again.

Worked example: a course page checklist and its defects

A training platform's course page has an English intro video with English and Arabic captions, a podcast episode, a background video in the page header, a promo carousel and a 15-minute session time-out. The intro video's presenter says aloud everything shown on screen, so it needs captions but no audio description. The tester first lists every media item and every time limit, then runs the checklist at the end of this section with the keyboard, a screen reader and the sound on, in both languages.

The defects found, written as bug titles with the criterion:

• “Header background video plays music with sound on load and has no controls at all” (1.4.2, 2.2.2)
• “Intro video: automatic English captions not reviewed; at 02:14 ‘fifteen minutes’ is captioned ‘fifty minutes’” (1.2.2)
• “Arabic captions: lines that start with the brand name are laid out left to right, with the full stop at the right end” (Arabic caption quality)
• “Podcast episode 7 has no transcript” (1.2.1)
• “Captions button is announced only as ‘button’, with no name and no on/off state” (4.1.2)
• “Session ends after 15 minutes idle with no warning; the half-written assignment is lost” (2.2.1)
• “Promo carousel advances every 4 seconds with no pause control and keeps rotating while focus is inside” (2.2.2)

MEDIA AND TIMING CHECKLIST: course page, build 4.12, en + ar

Inventory
[ ] Every media item classified: audio-only, video-only or synchronized; live or not
[ ] Every time limit listed: session, holds, countdowns, auto-advancing content
Prerecorded media
[ ] Audio-only: transcript linked next to the player (1.2.1)
[ ] Captions: in sync, accurate, speakers named, sound cues, to the end (1.2.2)
[ ] Visual-only information: audio description, or not needed (1.2.3, 1.2.5)
[ ] Arabic captions: right-to-left lines, Latin words and digits in order
Live media
[ ] Live sessions have captions (1.2.4)
Player
[ ] No sound over 3 s on load without pause, stop or volume control (1.4.2)
[ ] Tab, Enter/Space, arrows on sliders, visible focus (2.1.1, 2.4.7)
[ ] Names and states: Play/Pause, Captions on/off (4.1.2)
[ ] No trap in an embedded player; letter shortcuts only on focus (2.1.2, 2.1.4)
Timing
[ ] Each time limit can be turned off, adjusted (x10) or extended (2.2.1)
[ ] Extend: warning first, >= 20 s, one simple action, at least 10 times
[ ] Carousels, tickers: pause control (2.2.2); placed first, stops on focus (APG)

Try it: Test Case Generator Try it: AI QA Checklist Generator

Frequently asked questions

References

• Web Content Accessibility Guidelines (WCAG) 2.2W3C · 2024The W3C Recommendation that defines the testable success criteria for accessible web content, organised under four principles and three conformance levels (A, AA, AAA).
• Understanding WCAG 2.2W3C Web Accessibility Initiative (WAI)The informative explanation of each WCAG 2.2 guideline and success criterion: intent, who benefits, examples and techniques (not normative).
• ARIA Authoring Practices Guide (APG)W3C Web Accessibility Initiative (WAI)Patterns for common widgets (tabs, menus, dialogs, comboboxes) with the expected keyboard interaction and ARIA usage — the reference testers compare custom components against.
• HTML Living StandardWHATWGThe HTML language, including named character references (entities) and the parsing rules browsers follow.