Cobra Voice Activity Detection
C API

API Reference for the Cobra C SDK.

pv_cobra_t

typedef struct pv_cobra pv_cobra_t;

Container representing the Cobra VAD engine.

pv_cobra_init()

pv_status_t pv_cobra_init(const char *access_key, pv_cobra_t **object);

Creates a Cobra instance. Resources should be cleaned when you are done using the pv_cobra_delete() function.

Parameters

• access_key const char * : AccessKey obtained from Picovoice Console.
• object pv_cobra_t * * : Constructed instance of Cobra.

Returns

• pv_status_t : Status code.

pv_cobra_delete()

void pv_cobra_delete(pv_cobra_t *object);

Releases resources acquired by Cobra.

Parameters

• object pv_cobra_t * : Picovoice object.

pv_cobra_process()

pv_status_t pv_cobra_process(
    pv_cobra_t *object,
    const int16_t *pcm,
    float *is_voiced);

Processes a frame of the incoming audio stream and emits the probability of voice activity.

The number of samples per frame can be attained by calling pv_cobra_frame_length(). The incoming audio needs to have a sample rate equal to pv_sample_rate() and be 16-bit linearly-encoded. Cobra operates on single-channel audio.

Parameters

• object pv_cobra_t * : Cobra object.
• pcm int16_t : A frame of audio samples.
• is_voiced float * : Probability of voice activity. It is a floating-point number within [0, 1].

Returns

• pv_status_t : Status code.

pv_cobra_frame_length()

int32_t pv_cobra_frame_length(void);

Getter for number of audio samples per frame.

Returns

• int32_t : Frame length.

pv_cobra_version()

const char *pv_cobra_version(void);

Getter for version.

Returns

• const char * : Cobra version.

pv_sample_rate()

int32_t pv_sample_rate(void);

Audio sample rate accepted by Cobra.

Returns

• int32_t : Sample rate.

pv_status_t

typedef enum {
    PV_STATUS_SUCCESS = 0,
    PV_STATUS_OUT_OF_MEMORY,
    PV_STATUS_IO_ERROR,
    PV_STATUS_INVALID_ARGUMENT,
    PV_STATUS_STOP_ITERATION,
    PV_STATUS_KEY_ERROR,
    PV_STATUS_INVALID_STATE,
    PV_STATUS_RUNTIME_ERROR,
    PV_STATUS_ACTIVATION_ERROR,
    PV_STATUS_ACTIVATION_LIMIT_REACHED,
    PV_STATUS_ACTIVATION_THROTTLED,
    PV_STATUS_ACTIVATION_REFUSED
} pv_status_t;

Status code enum.

pv_status_to_string()

const char *pv_status_to_string(pv_status_t status);

Parameters

• status int32_t : Status code.

Returns

• const char * : String representation of status code.

pv_get_error_stack()

pv_status_t pv_get_error_stack(
        char ***message_stack,
        int32_t *message_stack_depth);

If a function returns a failure (any pv_status_t other than PV_STATUS_SUCCESS), this function can be called to get a series of error messages related to the failure. This function can only be called only once per failure status on another function. The memory for message_stack must be freed using pv_free_error_stack.

Regardless of the return status of this function, if message_stack is not NULL, then message_stack contains valid memory. However, a failure status on this function indicates that future error messages may not be reported.

Parameters

• message_stack const char * * * : Array of messages relating to the failure. Messages are NULL terminated strings. The array and messages must be freed using pv_free_error_stack().
• message_stack_depth int32_t * : The number of messages in the message_stack array.

Returns

• pv_status_t : Returned status code.

pv_free_error_stack()

void pv_free_error_stack(char **message_stack);

This function frees the memory used by error messages allocated by pv_get_error_stack().

Parameters

• message_stack const char * * * : Array of messages relating to the failure.