W3C home > Mailing lists > Public > w3c-wai-ua@w3.org > July to September 2009

Action on Increased Speed of Multimedia Playback

From: Kelly Ford <Kelly.Ford@microsoft.com>
Date: Thu, 24 Sep 2009 16:41:04 +0000
To: WAI-UA list <w3c-wai-ua@w3.org>
Message-ID: <3386240A0CB7B345B60441C3B253B2A104773FB0@TK5EX14MBXW653.wingroup.windeploy.ntdev.microsoft.com>
Hello,

Apologies that this is to the list and not a survey.  Here are my proposals to address my action around writing a guideline equivalent to 4.9.6 for increasing the speed of audio.


Current 4.9.6


4.9.6 Slow Multimedia: The user can slow the presentation rate of recognized<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-recognize> prerecorded audio and animation<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-animation> content, such that all of the following are true (Level A):
*         if only an audio track<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-audio-track> is present, provide at least one setting between 75% and 80% of the original speed.
*         if a visual track<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-visual-track> is present, provide at least one setting between 40% and 60% of the original speed.
*         when audio and video tracks are expected to be synchronized, synchronization is maintained as long as they are played at 75% of the original speed or higher.

Proposed 4.9.X

4.9.X Increase Multimedia: The user can increase the presentation rate of recognized<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-recognize> prerecorded audio and animation<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-animation> content, such that all of the following are true (Level AA):
*         if only an audio track<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-audio-track> is present, provide at least one setting between 110% and 140% of the original speed.
*         if a visual track<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-visual-track> is present, provide at least one setting between 110% and 120% of the original speed.
*         when audio and video tracks are expected to be synchronized, synchronization is maintained as long as they are played at 120% of the original speed or lower.

Note:
We might want a level AAA guideline around preserving audio characteristics.  I don't immediately recall the official term but it avoids the "chipmunk" effect when increasing audio playback rates and the deepening of the voice and such when slowing playback and is more common today when such features are offered.  I'm also looking for some official numbers on acceptable rates for playback and the ability to maintain comprehension.

The other guideline I'm talking about might read something like this:


4.9.X Maintain Audio Characteristics: When playing recognized<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-recognize> prerecorded audio and animation<http://www.w3.org/WAI/UA/2009/ED-UAAG20-20090722/#def-animation>  sound at rates other than the default, speech characters are not distorted beyond X range (Level AAA).



I recognize this last is vague and I need to research the technical terminology and such but I hope it gets the point over.



Kelly
Received on Thursday, 24 September 2009 16:42:02 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 27 October 2009 06:52:15 GMT