stream_engine

Stream Engine Migration Guide 2.x to 3.x

Introduction

This document is intended to help developers transition from older stream engine library 2.x to latest stream engine version 3.0. It is written in the format of a change log with complementary information that will assist developer making a smooth transition.

Wait for callbacks

The tobii_engine parameter has been removed from the tobii_wait_for_callbacks prototype, since the tobii_engine interface is no longer part of the API:

tobii_error_t tobii_wait_for_callbacks( int device_count, tobii_device_t* const* devices );

The implicit time sync that occurred every 30 seconds has been removed from tobii_wait_for_callbacks. An explicit call to tobii_update_timesync is now required in order to synchronize host time with the tracker timestamps.

Firmware upgrade state

New function tobii_get_firmware_upgrade_state has been added to the API, it is used for querying the current firmware upgrade status of a device:

typedef enum tobii_firmware_upgrade_state_t
{
    TOBII_FIRMWARE_UPGRADE_STATE_NOT_IN_PROGRESS,
    TOBII_FIRMWARE_UPGRADE_STATE_IN_PROGRESS,
} tobii_firmware_upgrade_state_t;

tobii_error_t tobii_get_firmware_upgrade_state( tobii_device_t* device, tobii_firmware_upgrade_state_t* firmware_upgrade_state );

When a device is undergoing firmware upgrade it can be enumerated by stream engine but not used, the implementer needs to take this into account and call this function in order to check if the device is ready for use at each startup.

Tobii engine interface

The tobii_engine interface has been removed from the stream engine client API. A replacement API may be released at a later date. Old versions of the API will still be able to use this API, if the stream engine service or middleware service is installed on the host machine, only difference is that the device readiness will always be shown as TOBII_DEVICE_READINESS_READY.

User position guide stream

A new tobii_user_position_guide stream has been added to the API, which is used to help a user position their eyes correctly in the track box:

typedef struct tobii_user_position_guide_t
{
    int64_t timestamp_us;
    tobii_validity_t left_position_validity;
    float left_position_normalized_xyz[3];
    tobii_validity_t right_position_validity;
    float right_position_normalized_xyz[3];
} tobii_user_position_guide_t;

typedef void( *tobii_user_position_guide_callback_t )( tobii_user_position_guide_t const * user_position_guide, void* user_data );

tobii_error_t tobii_user_position_guide_subscribe( tobii_device_t* device, tobii_user_position_guide_callback_t callback, void* user_data );

tobii_error_t tobii_user_position_guide_unsubscribe( tobii_device_t* device );

Device supports for this new stream, can be queried through the capabilities API. This has been split into two separate capabilities, one for xy-axis and one for z-axis, this is due to the fact that not all trackers support z-axis position guide:

The user position guide stream will replace the tobii_eye_position_normalized stream which is now deprecated and only supported on older trackers.

Device info

New fields have been added to the tobii_device_info_t struct and array sizes has been updated:

typedef struct tobii_device_info_t
{
    char serial_number[256];
    char model[256];
    char generation[256];
    char firmware_version[256];
    char integration_id[128];
    char hw_calibration_version[128];
    char hw_calibration_date[128];
    char lot_id[128];
    char integration_type[256];
    char runtime_build_version[256];
} tobii_device_info_t;

New fields explained:

Notification name changes

The TOBII_NOTIFICATION_TYPE_COMBINED_GAZE_FACTOR_CHANGED notification name has been changed to TOBII_NOTIFICATION_TYPE_COMBINED_GAZE_EYE_SELECTION_CHANGED.

New error return code

New tobii_error_t return code:

New capabilities

More compound stream capabilities have been added to the tobii_capability_t enum.

typedef enum tobii_capability_t
{
    ...
    TOBII_CAPABILITY_COMPOUND_STREAM_USER_POSITION_GUIDE_XY,
    TOBII_CAPABILITY_COMPOUND_STREAM_USER_POSITION_GUIDE_Z,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_LIMITED_IMAGE,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_PUPIL_DIAMETER,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_PUPIL_POSITION,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_EYE_OPENNESS,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_3D_GAZE_PER_EYE,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_USER_POSITION_GUIDE_XY,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_TRACKING_IMPROVEMENTS,
    TOBII_CAPABILITY_COMPOUND_STREAM_WEARABLE_CONVERGENCE_DISTANCE,
} tobii_capability_t;

Updates to the Wearable API

New fields for combined gaze, convergence distance and tracking improvements has been added to the to tobii_wearable_data_t struct:

typedef struct tobii_wearable_data_t
{
    ...
    tobii_validity_t gaze_origin_combined_validity;
    float gaze_origin_combined_mm_xyz[3];
    tobii_validity_t gaze_direction_combined_validity;
    float gaze_direction_combined_normalized_xyz[3];
    tobii_validity_t convergence_distance_validity;
    float convergence_distance_mm;
    int tracking_improvements_count;
    tobii_wearable_tracking_improvement_t tracking_improvements[ 10 ];
    tobii_state_bool_t improve_user_position_hmd;
    tobii_state_bool_t increase_eye_relief;
} tobii_wearable_data_t;

New fields for position guide signal has been added to the tobii_wearable_eye_t struct:

typedef struct tobii_wearable_eye_t
{
    ...
    tobii_validity_t position_guide_validity;
    float position_guide_xy[2];
} tobii_wearable_data_t;

The tracking_improvements field can have the following values:

typedef enum tobii_wearable_tracking_improvement_t
{
    TOBII_WEARABLE_TRACKING_IMPROVEMENT_USER_POSITION_HMD,
    TOBII_WEARABLE_TRACKING_IMPROVEMENT_CALIBRATION_CONTAINS_POOR_DATA,
    TOBII_WEARABLE_TRACKING_IMPROVEMENT_CALIBRATION_DIFFERENT_BRIGHTNESS,
    TOBII_WEARABLE_TRACKING_IMPROVEMENT_IMAGE_QUALITY,
    TOBII_WEARABLE_TRACKING_IMPROVEMENT_INCREASE_EYE_RELIEF,
} tobii_wearable_tracking_improvement_t;