W3C home > Mailing lists > Public > w3c-wai-ig@w3.org > January to March 2017

Re: Videos - do we need both captions and transcripts?

From: Michael A. Peters <mpeters@domblogger.net>
Date: Fri, 3 Feb 2017 10:35:48 -0800
To: w3c-wai-ig@w3.org
Message-ID: <63cf097c-98c3-09ce-c55a-b395a791e14f@domblogger.net>
On 02/03/2017 09:43 AM, Gregg C Vanderheiden wrote:
>> On Feb 3, 2017, at 6:07 PM, John Foliot <john@foliot.ca
>> <mailto:john@foliot.ca>> wrote:
>> Both captions and video descriptions are synchronized to the "Master"
>> timeline of the video: their utility is based on this synchronization.
>> Transcripts (Gregg called them scripts, but I am unsure what his
>> differentiation is, however the *actual* WCAG definition is
>> for alternative for time-based
>> media - https://www.w3.org/TR/WCAG20/#alt-time-based-mediadef)
>> traditionally are not synced to the video resource, but (per the MAUR)
>> should instead take advantage of semantic structure (good headings,
>> inter-document navigation, etc.)
> A transcript is a text doc that contains a transcript of audio.
>   * It is only an alternative to a audio recording (or a talking head
>     where there is nothing to describe regarding the video).
> a Script is a text doc that contains a transcript of the audio and a
> text description of the important visual information
>   * a script is an alternative to an AV recording (a video or  movie)
> Synchronized media
>   * any time based media that needs to be synchronized with something
>     else such as video or audio or interaction
>   * Examples of media this is synchronized and not
>      1. an audio recording - is NOT Synchronized media
>      2. an video only recording - is NOT Synchronized media
>      3. an audio/video recording - IS Synchronized media
>      4. an audio recording that has  “press now” in it where what
>         happens depends on pressing at that point in time  - IS
>         Synchronized media
>      5. a video only recording where doing an action at different points
>         in the video has different results (e.g. clicking when you see
>         the car you want)  - IS Synchronized media
> The proper alternatives to the above  5 items
>  1. audio only —  alt is transcript
>  2. video only -   alt is either described video or a text description
>     of the video (the latter is better for deaf-blind access and is faster )
>  3. audio/video -  alt is captioned and described video — or a SCRIPT
>     containing all dialog and sounds and all important visual
>     information  (best for deaf blind)
>  4. Audio with time-based interaction — alt is a transcript with links
>     at the appropriate points in the transcript
>  5. video only with time based interaction — alt is a text description
>     of the visual information with links at the appropriate points in
>     the text description
> it would probably be a good idea to grab this and save it someplace like
> the Understanding WCAG 2.0  - maybe under the general GUIDELINE.
> best
> gregg

For html5 video it might be good to have examples for adding subtitles 
to the video itself rather than just as html5 track element because 
videos are often saved for stand-alone play.

I beliebe WebVTT subtitles can be added to mkv containers (and hence 
WebM) directly with mkvmerge, I'm not sure what has to be done to get 
WebVTT into MP4 containers, it may need to be converted to another format.
Received on Friday, 3 February 2017 18:36:19 UTC

This archive was generated by hypermail 2.3.1 : Friday, 3 February 2017 18:36:19 UTC