Proposed minimal requirements for audio/speech checkpoints.

Hello,

I propose that minimal requirements for the following checkpoints
from the 10 June draft [1] be established on the basis of 
property values in the CSS2 Recommendation [2]:

  4.8 Allow the user to configure and control the audio volume. 
  4.9 Allow the user to configure and control synthesized speech 
      playback rate.
  4.11 Allow the user to configure synthesized speech pitch, gender, 
       and other articulation characteristics.

The relevant CSS2 properties are 'volume' (in CSS, for speech
only, but we can generalize its values here) and the voice
characteristics properties of section 19.8 [3]: 

This is not a requirement for user agents to implement CSS, 
but to allow the same range of abstract values as specified in CSS.
CSS also allows numbers and percentages, but I don't want to
make those requirements.

For instance, for volume, the following range would be mapped to 
six "real" levels by the user agent: silent, x-soft, soft,
medium, loud, x-loud. Similarly, for speech-rate: x-slow,
slow, medium, fast, x-fast. The relative rates "faster" and
"slower" are relative values specific to CSS inheritance,
so would not be required.

I will write out the specific values for checkpoints 4.8, 4.9,
and 4.11, but for now I want to get feedback as to whether
people think that this is a reasonable approach. 

IMPORTANT: I propose that we delete "and other articulation
characteristics" from checkpoint 4.11 since that makes it
much harder to specify minimal requirements.

 - Ian

[1] http://www.w3.org/WAI/UA/WD-UAAG10-20000610/
[2] http://www.w3.org/TR/1998/REC-CSS2-19980512
[3]
http://www.w3.org/TR/1998/REC-CSS2-19980512/aural.html#voice-char-props
-- 
Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel:                         +1 831 457-2842
Cell:                        +1 917 450-8783

Received on Monday, 12 June 2000 15:13:07 UTC