W3C home > Mailing lists > Public > public-speech-api@w3.org > September 2012

Re: stabilityThreshold attribute

From: Glen Shires <gshires@google.com>
Date: Sun, 2 Sep 2012 21:29:02 -0700
Message-ID: <CAEE5bciTbAYa_Ef0y2FKOW7-zaGx3W6kW4jfvrVYutBRH4fBWQ@mail.gmail.com>
To: Satish S <satish@google.com>
Cc: public-speech-api@w3.org
I suspect that many JavaScript authors will only use final results, and not
make use of interim results. This keeps their code simple, also they
wouldn't need to set stabilityThreshold because the default is to NOT
include interim results.

Authors that choose to write the extra code to handle interim results would
also set stabilityThreshold to a value (other than the default).

Adding stabilityThreshold after v1 would be messy/inefficient because that
would mean that interim results are always sent in v1.  Thus, to avoid
changing the default behavior, if stabilityThreshold was added after v1,
then the default would have to be 0.0 instead of 1.0.  Thus, the default
would be to always use the most bandwidth and compute, rather than the
least.  I suspect that JavaScript authors that only use final results and
keep their code simple, may not bother to set stabilityThreshold
(especially because they need to version check to see if the feature is
available). Thus, this simple case will typically waste bandwidth and
compute, even if we add this feature after v1.  Therefore, I believe we
should put this in the spec for v1.

This proposal is flexible enough that a UA/speech-recognizer could
implement fine-grain stability. Conversely, a UA may use a trivial
implementation and be conformant, where all interim results are assigned
the same stability value (perhaps 0.5 for example), and stabilityThreshold
controls only whether no interim results, or all interim results are

/Glen Shires

On Sun, Sep 2, 2012 at 2:27 PM, Satish S <satish@google.com> wrote:

> I mentioned something similar for confidenceThreshold as well - this is
> really an optimisation for the speech service that most web developers
> would choose to ignore. Can this be added if there is a real need reported
> by developers after v1?
> Cheers
> Satish
> On Sat, Sep 1, 2012 at 3:51 PM, Glen Shires <gshires@google.com> wrote:
>> If there's no disagreement, I'll add this to the spec on Tuesday...
>> On Thu, Aug 30, 2012 at 10:55 AM, Glen Shires <gshires@google.com> wrote:
>>> For JavaScript authors that do not make use of interim results, or only
>>> want to show fewer and more stable interim results, the following
>>> stabilityThreshold would allow the author to request this, which reduces
>>> the bandwidth usage and the events fired (and thus also reduces compute and
>>> power).  In addition, the stability attribute returned with interim results
>>> would allow authors to process results according to their estimated
>>> stability. For example, an author might choose to display final results in
>>> black, fairly stable results in dark grey, and not very stable results in
>>> light grey.
>>> I propose the following:
>>> Add to IDL for SpeechRecognitionResult
>>>     readonly attribute float stability;
>>> Add to 5.1.6 Speech Recognition Result definitions
>>> stability
>>>   The stability represents a numeric estimate between 0.0 and 1.0 of how
>>> likely the recognition system is to change this interim result. A higher
>>> number indicates the result is less likely to change.  This attribute is
>>> not defined when the "final" attribute is true.
>>> Add to IDL for SpeechRecognition (the top level)
>>>     attribute float stabilityThreshold;
>>> Add to 5.1.1 Speech Recognition Attributes definitions:
>>>  stabilityThreshold
>>>   This attribute controls how many interim results are returned. When
>>> set to the value of 1.0, no interim results (only final results) will be
>>> returned.  When set to 0.0, all interim results will be returned. Valid
>>> values are in the range of 0.0 to 1.0 inclusive. The default value is 1.0.
>>> /Glen Shires
Received on Monday, 3 September 2012 04:30:11 UTC

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