Porcupine Wake Word
C API

API Reference for the Porcupine C SDK.

pv_porcupine_t

typedef struct pv_porcupine pv_porcupine_t;

Container representing the Porcupine wake word engine.

pv_porcupine_init()

pv_status_t pv_porcupine_init(
        const char *access_key,
        const char *model_path,
        const char *device,
        int32_t num_keywords,
        const char *const *keyword_paths,
        const float *sensitivities,
        pv_porcupine_t **object);

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

Parameters

• access_key const char * : AccessKey obtained from Picovoice Console.
• model_path const char * : Absolute path to the file containing model parameters (.pv).
• device char * : String representation of the device (e.g., CPU or GPU) to use. If set to best, the most suitable device is selected automatically. If set to gpu, the engine uses the first available GPU device. To select a specific GPU device, set this argument to gpu:${GPU_INDEX}, where ${GPU_INDEX} is the index of the target GPU. If set to cpu, the engine will run on the CPU with the default number of threads. To specify the number of threads, set this argument to cpu:${NUM_THREADS}, where ${NUM_THREADS} is the desired number of threads.
• num_keywords int32_t : Number of keywords to monitor.
• keyword_paths const char *const * : Absolute paths to keyword model files (.ppn).
• sensitivities float * : Sensitivities for detecting keywords. Each value should be a number within [0, 1]. A higher sensitivity results in fewer misses at the cost of increasing the false alarm rate.
• object pv_porcupine_t * * : Constructed instance of Porcupine.

Returns

• pv_status_t : Returned status code.

pv_porcupine_delete()

void pv_porcupine_delete(pv_porcupine_t *object);

Releases resources acquired by Porcupine.

Parameters

• object pv_porcupine_t * : Picovoice object.

pv_porcupine_process()

pv_status_t pv_porcupine_process(pv_porcupine_t *object, const int16_t *pcm, int32_t *keyword_index);

Processes a frame of the incoming audio stream and emits the detection result. The number of samples per frame can be attained by calling pv_porcupine_frame_length(). The incoming audio needs to have a sample rate equal to pv_sample_rate() and be 16-bit linearly-encoded. Porcupine operates on single-channel audio.

Parameters

• object pv_porcupine_t * : Porcupine object.
• pcm int16_t : A frame of audio samples.
• keyword_index int32_t * : Index of observed keyword at the end of the current frame. Indexing is 0-based and matches the ordering of keyword models provided to pv_porcupine_init(). If no keyword is detected then it is set to -1.

Returns

• pv_status_t : Returned status code.

pv_porcupine_version()

const char *pv_porcupine_version(void);

Getter for version.

Returns

• char * : Porcupine version.

pv_porcupine_frame_length()

int32_t pv_picovoice_frame_length(void);

Getter for number of audio samples per frame.

Returns

• int32_t : Frame length.

pv_porcupine_list_hardware_devices()

pv_status_t pv_porcupine_list_hardware_devices(
        char ***hardware_devices,
        int32_t *num_hardware_devices);

Gets a list of hardware devices that can be specified when calling pv_porcupine_init().

Parameters

• hardware_devices const char * * * : Array of available hardware devices. Devices are NULL terminated strings. The array must be freed using pv_porcupine_free_hardware_devices().
• num_hardware_devices int32_t * : The number of devices in the hardware_devices array.

Returns

• pv_status_t : Returned status code.

pv_porcupine_free_hardware_devices()

void pv_porcupine_free_hardware_devices(
        char ***hardware_devices,
        int32_t *num_hardware_devices);

This function frees the memory allocated by pv_porcupine_list_hardware_devices().

Parameters

• hardware_devices const char * * * : Array of available hardware devices allocated by pv_porcupine_list_hardware_devices().
• num_hardware_devices int32_t * : The number of devices in the hardware_devices array.

pv_sample_rate()

int32_t pv_sample_rate(void);

Audio sample rate accepted by Porcupine.

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

• int32_t : Returned status code.

Returns

• char * : String representation.

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.