pasting changes for voice-balance (more to come)

Author: danielweck

css3-speech/Overview.html

@@ -13,17 +13,17 @@
   <style type="text/css">
       p
       {
-        padding-bottom : 1em;
+          padding-bottom : 1em;
       }
 
       p + p
       {
-        text-indent : 0;
+          text-indent : 0;
       }
 
       *:target
       {
-        border : 1px dashed #66CC66;
+          border : 1px dashed #66CC66;
       }</style>
   <!--
       .prod
@@ -90,13 +90,13 @@
 
    <h1 id=top>CSS Speech Module</h1>
 
-   <h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 08 July 2011</h2>
+   <h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 13 July 2011</h2>
 
    <dl>
     <dt>This version:
 
     <dd>
-     <!--<a href="http://www.w3.org/TR/2011/WD-css3-speech-20110708">http://www.w3.org/TR/2011/ED-css3-speech-20110708/</a>-->
+     <!--<a href="http://www.w3.org/TR/2011/WD-css3-speech-20110713">http://www.w3.org/TR/2011/ED-css3-speech-20110713/</a>-->
      <a
      href="http://dev.w3.org/csswg/css3-speech">http://dev.w3.org/csswg/css3-speech</a>
 
@@ -694,15 +694,55 @@ <h3 id=mixing-props-voice-balance><span class=secno>5.2. </span>The
      <td>specified value
   </table>
 
-  <p>The &lsquo;<a href="#voice-balance"><code
-   class=property>voice-balance</code></a>&rsquo; property manipulates the
-   distribution of audio output between left and right channels in
-   stereo-capable sound devices.
+  <p> The &lsquo;<a href="#voice-balance"><code
+   class=property>voice-balance</code></a>&rsquo; property controls the
+   spatial distribution of audio output across a lateral sound stage: one
+   extremity is on the left, the other extremity is on the right hand side,
+   relative to the listener's position. Authors can specify intermediary
+   steps between left and right extremities, to represent the audio
+   separation along the resulting left-right axis.
 
   <p class=note> Note that the functionality provided by this property has no
    match in the SSML markup language <a href="#SSML"
    rel=biblioentry>[SSML]<!--{{!SSML}}--></a>.
 
+  <ul>
+   <li> When user-agents produce audio via a mono-aural sound system (i.e.
+    single-speaker setup), the &lsquo;<a href="#voice-balance"><code
+    class=property>voice-balance</code></a>&rsquo; property has no effect.
+
+   <li> When user-agents produce audio through a stereo sound system (e.g.
+    two speakers, a pair of headphones), the left-right distribution of audio
+    signals precisely match the authored values for the &lsquo;<a
+    href="#voice-balance"><code
+    class=property>voice-balance</code></a>&rsquo; property.
+
+   <li> When user-agents are capable of mixing audio signals through more
+    than 2 channels (e.g. 5-speakers surround sound system, including a
+    dedicated center channel), the physical distribution of audio signals
+    resulting from the application of the &lsquo;<a
+    href="#voice-balance"><code
+    class=property>voice-balance</code></a>&rsquo; property must be performed
+    so that the listener perceives sound as if it was coming from a basic
+    stereo layout. For example, the center channel as well as the left/right
+    speakers may be used altogether in order to emulate the behavior of the
+    &lsquo;<code class=property>center</code>&rsquo; value (zero, on the
+    [-100,100] scale of the &lsquo;<a href="#voice-balance"><code
+    class=property>voice-balance</code></a>&rsquo; property).
+  </ul>
+
+  <p class=note> Note that sound systems may be configured by users in such a
+   way that it would interfere with the left-right audio distribution
+   specified by document authors. Typically, the various "surround" modes
+   available in modern sound systems (including systems based on basic stereo
+   speakers) tend to greatly alter the perceived spatial arrangement of audio
+   signals. Some users may even configure their system to "downgrade" any
+   rendered sound to a single mono channel, in which case the effect of the
+   &lsquo;<a href="#voice-balance"><code
+   class=property>voice-balance</code></a>&rsquo; property would obviously
+   not be perceivable at all. The rendering fidelity of authored content is
+   therefore dependent on such user customizations.
+
   <dl>
    <dt> <strong>&lt;number&gt;</strong>
 
@@ -713,12 +753,13 @@ <h3 id=mixing-props-voice-balance><span class=secno>5.2. </span>The
      &lsquo;<code class=css>-100</code>&rsquo; are clamped to &lsquo;<code
      class=css>-100</code>&rsquo;. Values greater than &lsquo;<code
      class=css>100</code>&rsquo; are clamped to &lsquo;<code
-     class=css>100</code>&rsquo;. When the value is &lsquo;<code
-     class=css>-100</code>&rsquo;, only the left channel is audible.
-     Conversely, when the value is &lsquo;<code class=css>100</code>&rsquo;
-     only the right channel is audible. When the value is &lsquo;<code
-     class=css>0</code>&rsquo;, left and right channels both have the same
-     sound level, so that the speech appears to be coming from the center.</p>
+     class=css>100</code>&rsquo;. The value &lsquo;<code
+     class=css>-100</code>&rsquo; represents the left side, and the value
+     &lsquo;<code class=css>100</code>&rsquo; represents the right side. The
+     value &lsquo;<code class=css>0</code>&rsquo; represents the center point
+     whereby there is no discernible audio separation between left and right
+     sides (in a stereo sound system, this corresponds to equal distribution
+     of audio signals between left and right speakers).</p>
 
    <dt> <strong>left</strong>
 
@@ -738,31 +779,26 @@ <h3 id=mixing-props-voice-balance><span class=secno>5.2. </span>The
    <dt> <strong>leftwards</strong>
 
    <dd>
-    <p>Moves the sound to the left, relative to the inherited &lsquo;<a
-     href="#voice-balance"><code
-     class=property>voice-balance</code></a>&rsquo;. More precisely, subtract
-     20 from the inherited value and clip the resulting value to the range
-     &lsquo;<code class=css>-100</code>&rsquo; and &lsquo;<code
-     class=css>100</code>&rsquo;.</p>
+    <p>Moves the sound to the left, by subtracting 20 from the inherited
+     &lsquo;<a href="#voice-balance"><code
+     class=property>voice-balance</code></a>&rsquo; value, and by clamping
+     the resulting number to &lsquo;<code class=css>-100</code>&rsquo;.</p>
 
    <dt> <strong>rightwards</strong>
 
    <dd>
-    <p>Moves the sound to the right, relative to the inherited &lsquo;<a
+    <p>Moves the sound to the right, by adding 20 to the inherited &lsquo;<a
      href="#voice-balance"><code
-     class=property>voice-balance</code></a>&rsquo;. More precisely, add 20
-     to the inherited value and clip the resulting value to the range
-     &lsquo;<code class=css>-100</code>&rsquo; and &lsquo;<code
-     class=css>100</code>&rsquo;.</p>
+     class=property>voice-balance</code></a>&rsquo; value, and by clamping
+     the resulting number to &lsquo;<code class=css>100</code>&rsquo;.</p>
   </dl>
 
   <p class=note> Note that many speech synthesizers only generate mono sound,
    and therefore do not intrinsically support the &lsquo;<a
    href="#voice-balance"><code class=property>voice-balance</code></a>&rsquo;
-   property. The distribution of audio signals between left and right
-   channels would consequently occur at post-synthesis stage, for example
-   when a speech-enabled user-agent mixes the various audio sources that may
-   be authored within the document.
+   property. The sound distribution along the left-right axis consequently
+   occurs at post-synthesis stage (when the speech-enabled user-agent mixes
+   the various audio sources authored within the document)
 
   <h2 id=speaking-props><span class=secno>6. </span>Speaking properties</h2>
 

css3-speech/Overview.src.html

@@ -9,17 +9,17 @@
     <style type="text/css">
       p
       {
-        padding-bottom : 1em;
+          padding-bottom : 1em;
       }
 
       p + p
       {
-        text-indent : 0;
+          text-indent : 0;
       }
 
       *:target
       {
-        border : 1px dashed #66CC66;
+          border : 1px dashed #66CC66;
       }</style>
     <!--
       .prod
@@ -412,20 +412,48 @@ <h3 id="mixing-props-voice-balance">The 'voice-balance' property</h3>
         </tr>
       </tbody>
     </table>
-    <p>The 'voice-balance' property manipulates the distribution of audio output between left and
-      right channels in stereo-capable sound devices.</p>
+    <p> The 'voice-balance' property controls the spatial distribution of audio output across a
+      lateral sound stage: one extremity is on the left, the other extremity is on the right hand
+      side, relative to the listener's position. Authors can specify intermediary steps between left
+      and right extremities, to represent the audio separation along the resulting left-right axis. </p>
+
     <p class="note"> Note that the functionality provided by this property has no match in the SSML
       markup language [[!SSML]]. </p>
+
+    <ul>
+      <li> When user-agents produce audio via a mono-aural sound system (i.e. single-speaker setup),
+        the 'voice-balance' property has no effect. </li>
+      <li> When user-agents produce audio through a stereo sound system (e.g. two speakers, a pair
+        of headphones), the left-right distribution of audio signals precisely match the authored
+        values for the 'voice-balance' property. </li>
+      <li> When user-agents are capable of mixing audio signals through more than 2 channels (e.g.
+        5-speakers surround sound system, including a dedicated center channel), the physical
+        distribution of audio signals resulting from the application of the 'voice-balance' property
+        must be performed so that the listener perceives sound as if it was coming from a basic
+        stereo layout. For example, the center channel as well as the left/right speakers may be
+        used altogether in order to emulate the behavior of the 'center' value (zero, on the
+        [-100,100] scale of the 'voice-balance' property). </li>
+    </ul>
+
+    <p class="note"> Note that sound systems may be configured by users in such a way that it would
+      interfere with the left-right audio distribution specified by document authors. Typically, the
+      various "surround" modes available in modern sound systems (including systems based on basic
+      stereo speakers) tend to greatly alter the perceived spatial arrangement of audio signals.
+      Some users may even configure their system to "downgrade" any rendered sound to a single mono
+      channel, in which case the effect of the 'voice-balance' property would obviously not be
+      perceivable at all. The rendering fidelity of authored content is therefore dependent on such
+      user customizations. </p>
     <dl>
       <dt>
         <strong>&lt;number&gt;</strong>
       </dt>
       <dd>
         <p>A <a href="#number-def">number</a> between '-100' and '100' (inclusive). Values smaller
-          than '-100' are clamped to '-100'. Values greater than '100' are clamped to '100'. When
-          the value is '-100', only the left channel is audible. Conversely, when the value is '100'
-          only the right channel is audible. When the value is '0', left and right channels both
-          have the same sound level, so that the speech appears to be coming from the center.</p>
+          than '-100' are clamped to '-100'. Values greater than '100' are clamped to '100'. The
+          value '-100' represents the left side, and the value '100' represents the right side. The
+          value '0' represents the center point whereby there is no discernible audio separation
+          between left and right sides (in a stereo sound system, this corresponds to equal
+          distribution of audio signals between left and right speakers). </p>
       </dd>
       <dt>
         <strong>left</strong>
@@ -449,24 +477,21 @@ <h3 id="mixing-props-voice-balance">The 'voice-balance' property</h3>
         <strong>leftwards</strong>
       </dt>
       <dd>
-        <p>Moves the sound to the left, relative to the inherited 'voice-balance'. More precisely,
-          subtract 20 from the inherited value and clip the resulting value to the range '-100' and
-          '100'.</p>
+        <p>Moves the sound to the left, by subtracting 20 from the inherited 'voice-balance' value,
+          and by clamping the resulting number to '-100'.</p>
       </dd>
       <dt>
         <strong>rightwards</strong>
       </dt>
       <dd>
-        <p>Moves the sound to the right, relative to the inherited 'voice-balance'. More precisely,
-          add 20 to the inherited value and clip the resulting value to the range '-100' and
-          '100'.</p>
+        <p>Moves the sound to the right, by adding 20 to the inherited 'voice-balance' value, and by
+          clamping the resulting number to '100'.</p>
       </dd>
     </dl>
     <p class="note"> Note that many speech synthesizers only generate mono sound, and therefore do
-      not intrinsically support the 'voice-balance' property. The distribution of audio signals
-      between left and right channels would consequently occur at post-synthesis stage, for example
-      when a speech-enabled user-agent mixes the various audio sources that may be authored within
-      the document. </p>
+      not intrinsically support the 'voice-balance' property. The sound distribution along the
+      left-right axis consequently occurs at post-synthesis stage (when the speech-enabled
+      user-agent mixes the various audio sources authored within the document) </p>
     <h2 id="speaking-props">Speaking properties</h2>
     <h3 id="speaking-props-speak">The 'speak' property</h3>
     <table class="propdef" summary="name: syntax">