Re: voice-volume, absolute and relative volume units [css3-speech][css3-values][CSS-ISSUE-184]

On 07/06/2011 02:34 PM, Daniel Weck wrote:
> On 29 Jun 2011, at 23:43, L. David Baron wrote:
>> defines a relative
>> 'dB' unit (which does make sense as a relative unit), which
>> CSS-ISSUE-184 proposes to move to css3-values.
>> However, the 'voice-volume' property then says its computed value is
>> "specified value", which doesn't make sense for relative values. In
>> particular, an element with 'voice-volume: +5dB' should have a
>> different computed value depending on what its inherited value was.
>> We've had lots of problems in the past when we had properties whose
>> computed values couldn't be represented as valid syntax for the
>> property. I think adding another such case (I think we've fixed the
>> existing ones, e.g., with the 'font-weight' changes in CSS 2.1) is a
>> bad idea. So I think if you want relative units in this manner, you
>> should also have a syntax for combining them with the possible
>> absolute values.
> I understand the problem you are describing, but I can't figure-out
> a way to solve it. Absolute values for the audio amplitude
> level are materialized via the x-soft, soft, medium, loud, x-loud
> keywords, but this is still dependent on the selected voice
> instance (and it is linked to the perceived loudness, i.e. to the user).

I think you need to drop the 'normal' value. At least, I have no idea
what it would mean. The initial value should be 'medium'.

Then make the Computed Value line read something like

   Computed Value: a keyword and, if it is not zero, a decibel value

Then the computed value is always a keyword plus a <decibel>, which
will represent any changes. Then make the value allow both a keyword
and a <decibel> to be specified simultaneously (using ||).

I believe that would solve the problem.


Received on Wednesday, 6 July 2011 22:50:11 UTC