Help with cont_ad_calib

[Shane]

Hello,

I'm trying to write a little program that uses the pocketsphinx library to do
some continuous speech recognition. However when I try to calibrate the
initial silence threshold (cont_ad_calib(cont)) I get a negative number
returned to me. What are the possible reasons for this?

Thanks in advance

[Nickolay V. Shmyrev]

Hello

It might be noisy audio or byte endian issue. If noise is too much calibration
can fail. To get more information enable cont_ad debugging by calling

cont_ad_set_logfp(cont_ad_t * r, FILE * fp)

with stdout argument to output debug info on stdout.

[Shane]

Ok, I called cont_ad_st_logfp but it doesn't seem to have printed anything to
the screen. Here is the line I put in:

int res = cont_ad_set_logfp(cont,stdout);

Which returns 0 to signal success but doesn't seem to do anything.

[Nickolay V. Shmyrev]

Well, then maybe your ad doesn't function at all, are you sure it's not NULL?

It's actually very easy to find that out, you can just go step by step through
a function with a debugger.

[Shane]

I'm pretty sure it isn't. Let me give you a quick snippet of the code. It's
basically been taken from the HelloWorld tutorial and looking at continuous.c.
Here it is:

#define DEFAULT_DEVICE NULL

//...

ps_decoder_t *ps;
cmd_ln_t *config;

config = cmd_ln_init(NULL, ps_args(), TRUE,
                "-hmm", "../pocketsphinx-0.7/model/hmm/en_US/hub4wsj_sc_8k",
                "-lm", "../pocketsphinx-0.7/model/lm/en/turtle.DMP",
                "-dict", "../pocketsphinx-0.7/model/lm/en/turtle.dic",
                NULL);
if(config == NULL)
{
    printf("Config Initialization failed");
    system("Pause");
    return 1;
}

//PS Initializing
ps = ps_init(config);
if (ps == NULL)
    return 1;

//Continuous listening
ad_rec_t* ad;
int16 adbuf[4096];
int32 k, ts, rem;
cont_ad_t *cont;
char word[256];

if((ad = ad_open_dev(DEFAULT_DEVICE, DEFAULT_SAMPLES_PER_SEC)) == NULL)
{
    printf("Falied to open audio device\n");
    system("pause");
    return 1;
}

if((cont = cont_ad_init(ad, ad_read)) == NULL)
{
    printf("Failed to initialize voice activity detection\n");
    system("pause");
    return 1;
}

int res = cont_ad_set_logfp(cont,stdout);

if(cont_ad_calib(cont) < 0)
{
    printf("Failed to calibrate voice activity detection\n");
    system("pause");
    return 1;
}

[Shane]

And it gets past the initializing of ad and the initializing of cont but
cont_ad_calib returns -1. Is there perhaps something wrong further up in the
code? This is basically the whole program.

[Nickolay V. Shmyrev]

Hello

In this sample you miss ad_start_rec before cont_ad_calib:

  if (ad_start_rec(ad) < 0) {
        return 1;
    }

See continuous.c in src/programs for details.

[Nickolay V. Shmyrev]

I've also just committed a fix to show a message when recording is not
started, this should be easier to debug now.

[Shane]

Thank you, that was the problem. I appreciate the help!