Same input produces different hyptheses

[Gregory Hassett]

Hi, I am creating a pocketsphinx decoder to decode audio. In my grammar and
dictionary, "Operator, what time is it" is a valid command.

I capture audio of me saying, clearly, "What time is it", and pass it to the
decoder. It usually gets it right -- the first time I call it!

Subsequent calls are unpredictable... eventually I created a simple test
routine that passes the same audio, over and over, into the same ps_decoder.
And lo and behold, it gets different results each time. I thought that maybe I
was passing too much data at once to ps_process_raw, but I tried breaking it
into small chucks (same result). I thought maybe I'm missing some kind of call
to "ps_reset_decoder" or something, but I could not find any such API method.

Any idea why pocketsphinx would return different results for subsequent runs
on the same data? Here's my (very simple) C test function, and its results:

void testPS (ps_decoder_t *ps, SInt16* buf, int count)
{
    int32 recognitionScore = 0;
    char const *pocketSphinxHypothesis = NULL;
    char const *outUtteranceId = NULL;

    for (int i = 0;i < 500; ++i)
    {
        ps_start_utt (ps, NULL);
        ps_process_raw (ps, buf, count, FALSE, FALSE);
        ps_end_utt (ps);
        pocketSphinxHypothesis = ps_get_hyp (ps, &recognitionScore, &outUtteranceId);

        if (pocketSphinxHypothesis)
        {
            printf ("Run %d gets hypo: %s\n", i, pocketSphinxHypothesis);
        }
        else
        {
            printf ("Run %d gets null hypo\n", i);
        }

    }
}

Run 0 gets hypo: operator what time is it
Run 1 gets hypo: operator what time
Run 2 gets null hypo
Run 3 gets hypo: operator
Run 4 gets null hypo
Run 5 gets null hypo
Run 6 gets null hypo
Run 7 gets hypo: operator
Run 8 gets null hypo
Run 9 gets hypo: operator
Run 10 gets null hypo
Run 11 gets hypo: operator
Run 12 gets null hypo
Run 13 gets null hypo
Run 14 gets null hypo
Run 15 gets null hypo
Run 16 gets null hypo
Run 17 gets null hypo
Run 18 gets null hypo
Run 19 gets null hypo
Run 20 gets hypo: operator
Run 21 gets null hypo
Run 22 gets hypo: operator long
Run 23 gets null hypo
Run 24 gets null hypo
Run 25 gets hypo: operator
Run 26 gets hypo: operator
Run 27 gets hypo: operator
Run 28 gets null hypo
Run 29 gets hypo: operator
Run 30 gets null hypo
Run 31 gets null hypo
Run 32 gets null hypo
Run 33 gets null hypo
Run 34 gets null hypo
Run 35 gets null hypo
Run 36 gets hypo: operator
Run 37 gets hypo: operator what time is it

etc., etc.,

[Nickolay V. Shmyrev]

Hello

I can't reproduce your issue. Please provide a test case.