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Re: [free-aria] Re: Seeking feedback on HTML5 video accessibility ?experiment

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Sun, 2 Aug 2009 13:04:17 +1000
Message-ID: <2c0e02830908012004v5ac8983albb35185e4196facd@mail.gmail.com>
To: Victor Tsaran <vtsaran@yahoo-inc.com>
Cc: wai-xtech@w3.org
Hi Victor, all,

I just watched your video at
http://video.yahoo.com/watch/514676/2686894 after receiving some
private emails from several members of this group. I have promptly
added headers and more comments to the demo at
http://www.annodex.net/~silvia/itext/ . Please note that I am not
experience in general Web accessibility, but only know my way around
video and time-aligned text such as captions and subtitles. This is
the challenge I am addressing.

Now, I have to apologize to everyone because I probably made some
assumptions about the HTML5 video tag that I should not have made
(judging from the emails that I received). So, let me take a step back
and explain about the status of HTML5 video.

Firstly, html5 video is a very new tag that has not been implemented
in all browsers yet - and not all browsers support the Ogg
Theora/Video codec that my demo uses. Only the latest Firefox 3.5
release will support my demo out of the box. For Chrome and Opera you
will have to use the latest nightly build (which I am not even sure
are publicly available). IE does not support it at all. For
Safari/Webkit you will need the latest release and install the XiphQT
quicktime component to provide support for the codec.

My recommendation is clearly to use Firefox 3.5 to try this demo.

Secondly, the standardisation of the HTML5 video tag is still in
process. Some of the attributes have not been validated through
implementations, some of the use cases have not been turned into
specifications, and most importantly to the group here, there have
been very little experiments with accessibility around the HTML5 video

Most of the comments that I received were concerned with the
accessibility of the video controls, which is not an area I intended
to look into, assuming that would already be solved by the browsers.
However, I will have to do some work on it, if simply to enable people
to actually test the demo.

So, let me explain about the video controls.

In HTML5 video, there is a attribute called @controls. If it is
available, the browser is expected to display default controls on top
of the video. Here is what the current specification says:

"This user interface should include features to begin playback, pause
playback, seek to an arbitrary position in the content (if the content
supports arbitrary seeking), change the volume, and show the media
content in manners more suitable to the user (e.g. full-screen video
or in an independent resizable window)."

In Firefox 3.5, the controls attribute currently creates the following controls:
* play/pause button (toggles between the two)
* slider for current playback position and seeking (also displays how
much of the video has currently been downloaded)
* duration display (just display)
* roll-over button for volume on/off and to display slider for volume
* FAIK fullscreen is not currently implemented

Further, the HTML5 specification prescribes that if the @controls
attribute is not available, "user agents may provide controls to
affect playback of the media resource (e.g. play, pause, seeking, and
volume controls), but such features should not interfere with the
page's normal rendering. For example, such features could be exposed
in the media element's context menu."

In Firefox 3.5, this has been implemented with a right-click context
menu, which contains:
* play/pause toggle
* mute/unmute toggle
* show/hide controls toggle

When the controls are being displayed, there are keyboard shortcuts to
control them:
* space bar toggles between play and pause
* left/right arrow winds video forward/back by 5 sec
* CTRL+left/right arrow winds video forward/back by 60sec
* HOME+left/right jumps to beginning/end of video
* when focused on the volume button, up/down arrow increases/decreases volume

As for exposure of these controls to screen readers, Mozilla
implemented this in June, see Marco Zehe's blog post on it:

So, this is the current state of HTML5 video technology.

My work is actually meant to take this further and explore how to deal
with what I call time-aligned text files for video and audio. For the
purposes of this mailing list, we are mainly concerned with subtitles,
captions, and audio descriptions that come in textual form and should
be read out by a screen reader or made available to braille devices.

I am concerned both with time-aligned text that comes within a video
file, but also those that are available as external Web resources and
are just associated to the video through HTML. It is this latter use
case that my demo explored.

To create a nice looking demo, I used a skin for the video player that
was developed by somebody else. Now, I didn't pay attention to whether
that skin was actually accessible and this is the source of most of
the problems that have been mentioned to me thus far.

I will endeavor to make a new demo soon that doesn't use this skin,
but creates a menu for available text tracks in a different manner.
Then, I will post this here again and you should be able to make use
of the existing accessibility functionality for video, as well as the
new features I am proposing.

Best Regards,

On Sat, Aug 1, 2009 at 8:01 PM, Silvia
Pfeiffer<silviapfeiffer1@gmail.com> wrote:
> Hi Victor,
> It is the last control on the bottom right of the video player and it
> is only accessible with the mouse (as far as I know). It's the oval
> blue control. I am not bothering to improve this since the complete
> skin is only a made-up skin for the sake of including the menu for the
> different text tracks. But if you know a way in which to make it
> accessible, please let me know and I'd be more than happy to improve
> the demo with it.
> Thanks,
> Silvia.
> On Sat, Aug 1, 2009 at 2:57 AM, Victor Tsaran<vtsaran@yahoo-inc.com> wrote:
>> Hi Sylvia,
>> "little round thing on the far right", you say? Can you plese be more
>> specific?
>> Thanks,
>> V
>> -----Original Message-----
>> From: wai-xtech-request@w3.org [mailto:wai-xtech-request@w3.org] On
>> Behalf Of Silvia Pfeiffer
>> Sent: Friday, July 31, 2009 12:14 AM
>> To: wai-xtech@w3.org
>> Subject: Re: [free-aria] Re: Seeking feedback on HTML5 video
>> accessibility experiment
>> Further let me point out today's email to the WHATWG mailing list,
>> which contains some more details:
>> http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-July/021658.htm
>> l
>> BTW: the loudness can be changed on the little round thing on the far
>> right.
>> Best Regards,
>> Silvia.
Received on Sunday, 2 August 2009 03:05:14 UTC

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