Devices and Half-Span Angle
To achieve the optimal 3D spatial audio quality, the SDK needs to understand what type of physical audio equipment setup the user has. To this end, there are some imm_audio_control settings that allow for this information to be set for each participant.
First each participant will want to set their IMM_CONTROL_DEVICE which tells the Immersitech library the type of device they are using. They should choose to set IMM_CONTROL_DEVICE to IMM_DEVICE_HEADPHONE if they are using any type of headphone such as in-ear, on-ear, or over-ear headphones. If a user has a stereo pair of loudspeakers set up, they should set IMM_CONTROL_DEVICE to IMM_DEVICE_SPEAKER. By default, IMM_CONTROL_DEVICE is set to IMM_DEVICE_HEADPHONE and if a user doesn't have either of these devices or doesn't understand their setup it is recommended to leave this default.
When IMM_CONTROL_DEVICE is set to IMM_DEVICE_SPEAKER, a user must also set up the IMM_CONTROL_HALF_SPAN_ANGLE properly to achieve proper spatial 3D. This parameter is not used when a participant's IMM_CONTROL_DEVICE is set to IMM_DEVICE_HEADPHONE, it only applies for participants that are using speakers. IMM_CONTROL_HALF_SPAN_ANGLE lets the SDK know the relative angle the user is to the physical speakers they are listening to. The angle can be from 1 to 90 degrees (integer values). For quick reference, the following devices may be around the half span angle listed below:
- 7 degrees for portable speakers
- 15 degrees for laptop speakers
- 25 degrees for larger television sound bars
- 30 to 45 degrees for studio speaker setups
To find the half span angle for your setup, you can measure the distance from your head to your speakers and also the distance between your speakers to calculate the angle as pictured below: