[Accessibility] TTS API - voice selection

[Jonathan Duddington]

Some questions/clarifications:

1. Can an application call set_voice_by_properties() without a previous
call of set_driver() ?  i.e. use a default (preferred) synthesizer
which has been set up in Speech Dispatcher as a whole rather than
particular synthesizer which is known to the application?


2. set_voice_by_properties() states that fields in voice_description_t
may be "blank".  Does "blank" mean a NULL pointer, or a pointer to a
zero character (i.e. an empty string), or either?  This should be
specified.


3. list_drivers() and list_voices() return lists of driver and voice
descriptions.  It should be specified how the end of these lists is
indicated.


4. Can an application call set_voice_by_properties() with a
voice_description_t which has ALL its fields blank?  i.e. to choose the
default voice in the default language (as currently set in Speech
Dispatcher).  For example, an email client may not know the language of
the text that it's displaying.


5. Consider an application which wants to indicate text spoken either
with the "default" voice or an "alternate" voice.  For example, an
"alternate voice" may be wanted by a word processor speaking italic
text, or a web browser speaking "blockquote" text, or an email client
speaking quoted text.

Does the application simply call set_voice_by_properties() with blank
voice_descripton fields and variant=0 to select the default voice, and
then variant=1 to select an alternative voice (and variant=2 for a
additional level of quoting)?  Or should that be variant=1, 2, and 3?


6. While speaking SSML, if a <voice> <s> or <p> tag within the text
indicates a change to a language which is not supported by the current
synthesizer, is it intended that the synthesizer should report this to
S.D. which could then use a different synthesizer for that part of the
text?  Or is it intended that SSML tags can only change to a voice
within the same synthesizer?

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