Re: Why is there no alt attribute associated with the poster attribute on a video element (or, what's the accessible name calculation on a video element

Hi Silvia,

Thanks for your reply. So when you say alt attribute for the video do you
mean it looks like the below example?

Example  -

<video width="320" height="240" poster="/images/w3schools_green.jpg"
controls *alt="Bear catching a fish in a river"*>
   <source src="moviea.mp4" type="video/mp4">
   <source src="movaie.ogg" type="video/ogg">
   Your browser does not support the video tag.
</video>

There is no example of the video's alt attribute that I could find on the
internet.

I agree with you that there should be only one alternative field
describing the video. The poster  image is the visual summary and the alt
attribute is the textual summary of the video. There is no need to have an
alt attribute for the poster image as it's only purpose is to be a visual
summary of the video. This is true only when there exists an alt attribute
for the <video> tag as shown in the above example. Otherwise, the poster
property needs to have an alt attribute.

Another question for you- When the source of an image is broken we display
the alt text of the <img> tag. Does the alt property (if present) for the
<video> tag do the same?

Thanks,
Thrishma

On Sun, May 17, 2020 at 4:56 PM Silvia Pfeiffer <silviapfeiffer1@gmail.com>
wrote:

> Hey John,
>
> That's all a possibility, yes.
>
> So if your poster has different content from the video, your alt text
> should include the poster description, too, because it's supported by
> accessibility software. Introducing another attribute would require all
> accessibility software to be updated with two text alternatives for one
> element, which becomes very confusing very fast.
>
> Hope that helps.
>
> Best regards,
> Silvia.
>
> On Sun, May 17, 2020, 11:17 PM John Foliot <john.foliot@deque.com> wrote:
>
>> Silvia writes:
>>
>> > In essence: the poster is a visual summarisation of the video.
>>
>> Actually,  the poster  is  WAS ENVISIONED TO BE a visual summarisation
>> of the video, by the former HTML5 editor, who also demonstrated on multiple
>> occasions that he knew nothing of the accessibility space: the needs, the
>> users, their user experience, etc. and he frequently demonstrated his lack
>> of empathy in that regard.
>>
>> The reality is that the content author can point that @poster attribute
>> to ANY graphic image URI, including interstitials and/or 'placeholder'
>> slides (which may or may not contain "burned in" text intended for the
>> end-user) a reality that some engineers simply refuse to accept as a
>> possibility.
>>
>> Breaking this down:
>>
>> <video src="file.mp4"   <!-- this is a visual asset that requires a text
>> alternative, AKA an AccessibleName. Given its complexity, it also needs an
>> AccessibleDescription -->
>>
>>            poster="image.png">    <!-- this is a DIFFERENT visual asset
>> that also *potentially *requires a text alternative, AKA an
>> AccessibleName -->
>>
>>
>>
>>
>>
>> > You only need one summary in text.
>>
>>
>> Respectfully, you are wrong. I do not know where or how you arrive at
>> this assertion, but it is simply and clearly wrong:
>>
>> *Success Criterion 1.1.1 Non-text Content (Level A)**:*
>> *All non-text content* that is presented to the user has a text
>> alternative that serves the equivalent purpose... (JF: ALL, not some)
>>
>> The text alternative is not a "summary", it is an alternative to the
>> visual representation. Any time there is an image with text burned into it
>> the textual alternative is not a summarization of that text: it must be
>> faithfully and accurately replicated in text that can be processed by
>> machine (i.e. a screen reader).
>>
>> Evidence for all of this was also brought forward "back in the day",
>> along with multiple impassioned and detailed explanations about this topic
>> by daily screen reader users. Please, listen to the end users - they know
>> better than a sighted engineer will ever understand what they need and want.
>>
>> JF
>>
>> On Fri, May 15, 2020 at 5:18 PM Silvia Pfeiffer <
>> silviapfeiffer1@gmail.com> wrote:
>>
>>> There were lengthy discussions about this back in the day - you should
>>> be able to Google them.
>>>
>>> In essence: the poster is a visual summarisation of the video. The
>>> video's alt tag is a text summarisation of the video. You only need one
>>> summary in text.
>>>
>>> Hope this helps.
>>>
>>> Best regards,
>>> Silvia.
>>>
>>>
>>> On Fri, May 15, 2020, 12:59 AM thrishma reddy <thrishmareddy@gmail.com>
>>> wrote:
>>>
>>>> Hello,
>>>>
>>>> I was wondering if there was ever any solution to the question asked
>>>> here - https://github.com/w3c/html/issues/1431 (Why is there no alt
>>>> attribute associated with the poster attribute on a video element (or,
>>>> what's the accessible name calculation on a video element)?
>>>>
>>>>
>>>> Thanks,
>>>> Thrishma
>>>>
>>>>
>>
>> --
>> *​John Foliot* | Principal Accessibility Strategist | W3C AC
>> Representative
>> Deque Systems - Accessibility for Good
>> deque.com
>> "I made this so long because I did not have time to make it shorter." -
>> Pascal
>>
>>
>>
>>