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[media] what to do about "clean audio"

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Thu, 19 May 2011 10:36:13 +1000
Message-ID: <BANLkTikh06uNof1PFH92AHaBFvkt3M+aUQ@mail.gmail.com>
To: HTML Accessibility Task Force <public-html-a11y@w3.org>
In today's call we discussed what to do about the new information
about "clean audio" as dug up by Sean.

We are considering the following and would like to ask for your
thoughts / concerns / objections.


1. Dealing with "clean audio" in the Web Audio API

"Clean audio" is a technology that is being standardized by ETSI [1]
and EBU [2] in Europe. It is being defined on the audio channel level,
i.e. the level in which stereo is handled, too. For example, it
defines that the center channel in a 5.1 audio channel mix would
consist only of speech and could be amplified separately to all the
other channels. It is important to understand that it is being defined
on the audio channel level and not the audio track level. Therefore,
trying to add a track kind of "clean audio" to the track API of HTML
media elements is not going to work since this doesn't allow us to
separately control the volume of the "clean audio" channel in
comparison to the other channels.

The suggestion here is that this problem will be solved through the
Web Audio API. The Web Audio API indeed has controls for separately
addressing channels and changing the mix of different channels [3].
Therefore, the "clean audio" use case seems to be appropriately solved
through Web Audio API means.


2. Rename @track="clear audio" to @kind="speech"

While "clean audio" refers to a particular type of technology which
works on the channel level, the idea of providing a separate stream of
speech-only audio data that can be controlled seaprately in volume to
the normal/background audio is appealing and also allows to achieve
the "clean audio" effect, since it allows users to separately control
the volume of a speech track. This is not the "clean audio"
technology, so we should not use that same name for such a track.
Therefore, the suggestion is to call such a track "speech", which
seems semantically appropriate.

This will then require us to change the request in the @kind bug [4]
from asking for @kind="clearaudio" to @kind="speech". It would also
close the multitrack bug [5].

We plan to make those changes to these bugs after next week's phone
call, so hereby ask for input from everyone. In particular if you know
a "clean audio" expert, please ask him/her for advice on whether this
is the right way to approach it.

Best Regards,
Silvia.

[1] http://www.etsi.org/deliver/etsi_ts/101100_101199/101154/01.09.01_60/ts_101154v010901p.pdf
[2] http://tech.ebu.ch/docs/tech/tech3333.pdf
[3] http://www.w3.org/2011/audio/
[4] http://www.w3.org/Bugs/Public/show_bug.cgi?id=12544
[5] http://www.w3.org/Bugs/Public/show_bug.cgi?id=11593
Received on Thursday, 19 May 2011 00:37:00 GMT

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