[Olympus developers 217]: Re: N-best lists for PocketSphinx / Olympus

[Benjamin Frisch]

Hi Blaise,
  I think I actually fixed a similar bug in what became Olympus 2.5.  Are
you using that?  E-mail the list if you have questions about upgrading to
Olympus 2.5 if you are interested.  Either way, can you send me your
changes?  I'll try to get them committed if necessary.

Thanks,
Ben

On Wed, Mar 24, 2010 at 11:04 AM, Thomas Harris <tkharris at gmail.com> wrote:

> 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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