Update synchronized-media.html

[mbgower]

Adds a note to the synchronized media definition clarifying that the definition applies to any form of content that is intended to be part of an experience that combines more than one time-based medium.

Addresses comments such as #1790 (comment) in PR #1790

BB edit: See glossary entry for synchronized-media in preview.

[netlify]

✅ Deploy Preview for wcag2 ready!

Name	Link
🔨 Latest commit	7f02268
🔍 Latest deploy log	https://app.netlify.com/projects/wcag2/deploys/6839fce346779b0008471bc7
😎 Deploy Preview	https://deploy-preview-4371--wcag2.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[patrickhlauke]

"according to the same time base" sounds overly convoluted/impenetrable. perhaps something simpler, like "at the same time", "in parallel", or similar?

I think we've been trying to avoid "e.g.", "i.e.", and so on for simpler language. maybe replace here with "that is" or "for instance"?

maybe expand a bit what's mean by "Asynchronous sound", again using simpler language? Maybe a bit wordy, but something like "For instance, even if a video only includes 'incidental' music that does not explicitly synchronise with any of the visuals, ..."

[mbgower]

BTW, Patrick, "asynchronous" here is meant in its most basic meaning: "not existing or happening at the same time". It doesn't need to be incidental. It could be a voice over. It could be the 'natural sound' replaced by music, etc. It is any visual and audio which do not correspond. Even though they are not in synch it is still "synchronized media", which is about the shared time base of the playback. The definition is about the medium, not the message/material carried on it.

[bruce-usab]

My suggestion on call:

Some multimedia experiences may have artifacts where audio and video are not played exactly at the same time simultaneous but are still considered synchronized.

We also discussed adding examples.

[kfranqueiro]

RE the alternative of adding an example, @dbjorge suggested the following on the May 16 call:

Example: A website presents a slideshow with some background music. If the background music is presenting information, then it is synchronized media. If the background music is synchronized with the slideshow using a time-based interactive component - for example, a pause/play button that affects both the slideshow and the music - then it is also synchronized media. Otherwise, it is not synchronized media.

[mbgower]

If the background music is presenting information, then it is synchronized media... Otherwise, it is not synchronized media.

I don't understand what that first sentence means. The value of the background music is irrelevant. The fact there is an audio track that is timed with the video is what makes it possible to add audio descriptions. That is the only consideration we have in regard to our definition of "synchronized" in the context of audio-video.

@alastc I similarly don't understand the additions you have incorporated into your suggestion 'Both the visual and audio need to be "presenting information".' Do you mean that audio isn't just dead air?

I recommend making the first sentence: "If background music is part of the video, it is synchronized media." That addresses a direct question we had.

If the background music is synchronized with the slideshow using a time-based interactive component - for example, a pause/play button that affects both the slideshow and the music - then it is also synchronized media.

I also find we are getting into the weeds discussing time-based interactive components. If someone wants to create a separate example for an experience that accepts timed user actions, go ahead. But the specific issue here is confusion of what "synchronized" means in regard to audio-video.

All we seem to be doing here is more comprehensively confusing things.

---

I had a discussion this weekend with someone who does weekly AV broadcasts. They confirmed my prior opinion that anyone involved in this field will immediately grasp a concept of a "time base" in regard to synchronized media. A lot of their work is spent time-correcting cameras, monitor playback, etc.

I quickly found an existing definition that shows this term is in use:

Time base
Literally means timing reference. For example, on a typical watch the time base is in seconds. In music/video/film production it pertains to synchronization and has roughly the same meaning, though the units are often frames. The time base is the timing reference to which things are synchronizing.

Given the confusion with our current definition is arising from a technical point, I think we have to incorporate some consideration of a time base or timing reference into our update, without needing to burrow into technical concepts.

[dbjorge]

If the background music is presenting information, then it is synchronized media... Otherwise, it is not synchronized media.

I don't understand what that first sentence means. The value of the background music is irrelevant. The fact there is an audio track that is timed with the video is what makes it possible to add audio descriptions. That is the only consideration we have in regard to our definition of "synchronized" in the context of audio-video.

I feel like we're looking at different definitions. The "presenting information" terminology I used here is a verbatim quote from the normative WCAG 2.2 definition of "synchronized media":

synchronized media
audio or video synchronized with another format for presenting information and/or with time-based interactive components, unless the media is a media alternative for text that is clearly labeled as such

[mbgower]

The "presenting information" terminology I used here is a verbatim quote

IMO, the phrase "presenting information" in the definition you quote is intended generically. It implies no qualitative measure; however, the way it's used in the suggested example for synchronized media that Ken captured, it implies quality.

It suggests there exists some kind of music that contains no information, and that somehow we're supposed to be able to tell what that is.

[TestPartners]

I don't agree that muzak is information. That's like saying the background colour of a page is information. The muzak that accompanies videos could usually be replaced by any other tune or none at all, just as the background colour of a page can be any colour. The muzak and background colour clearly do not convey any information if they can be replaced without changing the meaning of the content. That is not the case when music is specifically chosen to convey a feeling such as danger or suspense and different music would convey a different feeling. I don't think it's difficult to tell the difference.

[dbjorge]

IMO, the phrase "presenting information" in the definition you quote is intended generically. It implies no qualitative measure

I agree that the wording is more ambiguous than I'd like for normative language, but I don't think it's reasonable to pick a meaning that assumes those words were included for no reason.

It suggests there exists some kind of music that contains no information, and that somehow we're supposed to be able to tell what that is.

This is no different from other parts of WCAG, where we expect evaluators to make exactly this determination to, for example, decide whether an image counts as "pure decoration".

[mbgower]

This is no different from other parts of WCAG, where we expect evaluators to make exactly this determination to, for example, decide whether an image counts as "pure decoration".

What I don't understand about this position is that it makes synchronized media a qualitative assessment. I see zero grounds for that.

Mechanically it makes no sense

For the purposes of audio descriptions, all we care about is that the audio and video are combined and synchronized, which 1) allows there to be an audio track (i.e., not video-only), and 2) allows someone to align the timing of the audio descriptions in the audio track with the appearance of the relevant visuals.

Audio descriptions are about visuals

Audio descriptions are not about providing an equivalent for sound, so what do we care what the nature of the existing audio is? The only way the soundtrack even enters into considerations for audio descriptions is in regard to identifying "pauses". We also have a potential consideration of a proposed sufficient technique (not yet approved) to use audio ducking. But those are both orthogonal to the synchronized media definition.

Time-based interactions seem unrelated

Finally, the reason I've been pushing back about attempts to incorporate a time-based interaction factor into this discussion is that it has no direct association with audio descriptions. Time-based interactions apply to a certain kind of synchronized media, but it's a consideration for which I've never seen any issues. And if there were any issues flagged, I cannot see how audio quality would fit into the synchronized media definition in that context either.

Perhaps the solution here is to put in a note in the audio descriptions definition that specifically talks about synchronized media in this context, instead of adding it as a note for the synchronized media definition?

[mbgower]

For example:

Note 5:
In the context of audio descriptions, "synchronized media" primarily refers to all audio and video content intended to be played to the same time base, which allows an author to align the timing of the audio descriptions in the audio track with the appearance of the relevant visuals in the video.
Intentionally asynchronous sound can take place in the context of time-based, synchronized media. A video that has poorly synchronized audio and video is still "synchronized media", as is a video accompanied only by background music.

[mbgower]

It might help to look at the definition of “synchronized media” with its definitions spelled out:

Synchronized media:
the technology of sound reproduction or the technology of moving or sequenced pictures or images synchronized with another format for presenting information and/or with time-based interactive components

You’ll note all that’s being talked about is technologies.

I feel like folks are trying to use the flimsy, undefined word “information” here for a qualitative argument, instead of focusing on the much more obvious idea that accessibility solutions of certain kinds only occur when audio and video are presented together.

It is incidental to the video information.

The argument has been advanced that because muzak is meaningless, a video with audio track wholly composed of muzak is not synchronized media. But that would mean no one is required to provide audio descriptions for the important visual information that is occurring at the same time. Is that really what people want?

Or, in another case, because the only thing being shown visually is a blank screen (i.e., black), I do not need to be providing captions of the dialogue taking place while the blank screen is shown.

Why would we even want that as a defence?

Think of it this way: because there is synchronized media, we can have a caption (on video), or an audio description (on audio). What is in the AV production and what is included (or not included) through either of these alternatives is immaterial to the technical ability to achieve the alternatives.

The author decides (and is judged) at the SC level on what is a sufficient alternative, but we must have the technical reality to even supply the alternative.

[bruce-usab]

Discussed on backlog call 5/30.