Re: [css3-speech] pitch alteration expressed in semitones and Hertz

Just in case this isn't obvious to those who are not familiar with the  
previous CSS3-Speech draft [1]:

The 'voice-pitch' and 'voice-pitch-range' properties were already  
featured, but only with support for fixed Hertz values, predefined  
named values, and percentage values (allowing relative changes in a  
multiplicative fashion). There was a pending issue regarding a  
discrepancy with SSML 1.0, which enables relative changes in an  
additive fashion (increments and decrements of non-percentage / fixed  
values) using both Hertz units and semitones.

I addressed this issue by adding an extra "value type" for the  
aforementioned properties, so the current specification is backward- 
compatible with the previous draft (none of the previous "value types"  
are affected by the change). Existing implementations only need to  
update the parsing algorithm, and to add the conversion from semitone  
offsets to fixed Hertz frequencies (which is based on trivial  

Regards, Daniel


On 19 Jan 2011, at 18:12, Daniel Weck wrote:

> Dear all,
> The latest editor's draft of the CSS3 Speech Module [1] now includes  
> support for pitch alteration ('voice-pitch' and 'voice-pitch-range')  
> based on relative changes (decrement or increment) expressed with  
> semitones and Hertz values. This addition provides better  
> compatibility with SSML 1.0 [2], and enables more sophisticated  
> authoring scenarios. The impact in terms of implementation costs is  
> relatively low (simple new parsing rules, and basic arithmetics to  
> compute pitch frequencies).
> Comments welcome.
> Regards, Daniel
> [1]
> [2]

Daniel Weck

Received on Wednesday, 19 January 2011 21:20:05 UTC