[Olympus developers 209]: Re: N-best lists for PocketSphinx / Olympus

[Thomas Harris]

Hi Blaise,

Thanks for looking into this. I hope we can include your bugfixes. I've been
looking into this as well, and there's a more fundamental issue. It seems
like you can't get word confidence metrics from the PocketSphinx segment
iterators when you've gotten the sement iterators from the n_best hypothisis
iterator. It smells like a PocketSphinx bug, but I haven't seen any
reference implementation of PocketSphinx that makes use of those confidence
metrics in an n_best setting, so I'm not sure that it isn't a problem with
how the PocketSphinx api is used. Until that issue is resolved n_best lists
won't work in Olympus, too many downhill processes depend on those
confidence metrics.

Thanks,
-Thomas

On Wed, Mar 24, 2010 at 4:39 AM, Blaise Thomson <brmt2 at cam.ac.uk> wrote:

> Dear Olympus developers,
>
> I am trying to get the Olympus LetsGo! system to provide an N-best list of
> speech recognition hypotheses. I found the -n_best switch which can be
> passed to the PocketSphinxEngine which is supposed to enable this but when I
> set the switch to anything other than 0 the system crashes immediately on
> any audio input. I remember you said that the system had been build to
> provide N-best lists so I was wondering if you could give any advice on why
> it is not working. Do you have a working N-best list system that you could
> send me to see how things are configured?
>
> In trying to solve the problem I took a look at the PocketSphinxEngine
> source code and have noticed some possible memory access bugs which may be
> contributing to this. These were related to the way the iHypsGenerated
> variable was used. I've fixed these and can send them if you would like (I
> tried attaching them but the mailing list won't let me). The resulting code
> still crashes but at a later stage. After the fix, the log file generates a
> WARNING: "ngram_search.c", line 1000:. I don't know if this might be the
> cause of the problem. There is also a possibility that I simply have to add
> a configuration variable to PocketSphinx itself. At the moment I have only
> used the n_best switch on PocketSphinxEngine.
>
> Please do let me know if you have any ideas of how to get this working or
> who else to contact.
>
> Thanks for all you help,
>
> Blaise
>
>
>
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