live.c

Speech recognition with live audio input and endpointing.

Speech recognition with live audio input and endpointing.This file shows how to use PocketSphinx in conjunction with sox to detect and recognize speech from the default audio input device.

This file shows how to use PocketSphinx to recognize a single input file. To compile it, assuming you have built the library as in these directions, you can run:

cmake --build build --target live

Alternately, if PocketSphinx is installed system-wide, you can run:

gcc -o live live.c $(pkg-config --libs --cflags pocketsphinx)

Sadly, this example does not seem to work on Windows, even if you manage to get sox in your PATH (which is not easy), because it seems that it can't actually read from the microphone. Try live_win32.c or live_portaudio.c instead.

/* Example of simple PocketSphinx speech segmentation.
 *
 * MIT license (c) 2022, see LICENSE for more information.
 *
 * Author: David Huggins-Daines <dhdaines@gmail.com>
 */
#include <pocketsphinx.h>
#include <signal.h>
 
static int global_done = 0;
static void
catch_sig(int signum)
{
    (void)signum;
    global_done = 1;
}
 
#ifdef WIN32
#define popen _popen
#define pclose _pclose
#endif
 
static FILE *
popen_sox(int sample_rate)
{
    char *soxcmd;
    int len;
    FILE *sox;
    #define SOXCMD "sox -q -r %d -c 1 -b 16 -e signed-integer -d -t raw -"
    len = snprintf(NULL, 0, SOXCMD, sample_rate);
    if ((soxcmd = malloc(len + 1)) == NULL)
        E_FATAL_SYSTEM("Failed to allocate string");
    if (snprintf(soxcmd, len + 1, SOXCMD, sample_rate) != len)
        E_FATAL_SYSTEM("snprintf() failed");
    if ((sox = popen(soxcmd, "r")) == NULL)
        E_FATAL_SYSTEM("Failed to popen(%s)", soxcmd);
    free(soxcmd);
 
    return sox;
}
 
int
main(int argc, char *argv[])
{
    ps_decoder_t *decoder;
    ps_config_t *config;
    ps_endpointer_t *ep;
    FILE *sox;
    short *frame;
    size_t frame_size;
 
    (void)argc; (void)argv;
    config = ps_config_init(NULL);
    ps_default_search_args(config);
    if ((decoder = ps_init(config)) == NULL)
        E_FATAL("PocketSphinx decoder init failed\n");
 
    if ((ep = ps_endpointer_init(0, 0.0, 0, 0, 0)) == NULL)
        E_FATAL("PocketSphinx endpointer init failed\n");
    sox = popen_sox(ps_endpointer_sample_rate(ep));
    frame_size = ps_endpointer_frame_size(ep);
    if ((frame = malloc(frame_size * sizeof(frame[0]))) == NULL)
        E_FATAL_SYSTEM("Failed to allocate frame");
    if (signal(SIGINT, catch_sig) == SIG_ERR)
        E_FATAL_SYSTEM("Failed to set SIGINT handler");
    while (!global_done) {
        const int16 *speech;
        int prev_in_speech = ps_endpointer_in_speech(ep);
        size_t len, end_samples;
        if ((len = fread(frame, sizeof(frame[0]),
                         frame_size, sox)) != frame_size) {
            if (len > 0) {
                speech = ps_endpointer_end_stream(ep, frame,
                                                  frame_size,
                                                  &end_samples);
            }
            else
                break;
        } else {
            speech = ps_endpointer_process(ep, frame);
        }
        if (speech != NULL) {
            const char *hyp;
            if (!prev_in_speech) {
                fprintf(stderr, "Speech start at %.2f\n",
                        ps_endpointer_speech_start(ep));
                ps_start_utt(decoder);
            }
            if (ps_process_raw(decoder, speech, frame_size, FALSE, FALSE) < 0)
                E_FATAL("ps_process_raw() failed\n");
            if ((hyp = ps_get_hyp(decoder, NULL)) != NULL)
                fprintf(stderr, "PARTIAL RESULT: %s\n", hyp);
            if (!ps_endpointer_in_speech(ep)) {
                fprintf(stderr, "Speech end at %.2f\n",
                        ps_endpointer_speech_end(ep));
                ps_end_utt(decoder);
                if ((hyp = ps_get_hyp(decoder, NULL)) != NULL)
                    printf("%s\n", hyp);
            }
        }
    }
    free(frame);
    if (pclose(sox) < 0)
        E_ERROR_SYSTEM("Failed to pclose(sox)");
    ps_endpointer_free(ep);
    ps_free(decoder);
    ps_config_free(config);
        
    return 0;
}