Definition
Microphone Array Geometry is a Data Type representing the position of each microphone comprising a Microphone Array and specific characteristics such as microphone type, look directions, and the array type.
Syntax
https://schemas.mpai.community/CAE/V2.1/data/MicrophoneArrayGeometry.json
Semantics
Table 1 gives the Semantics of Microphone Array Geometry.
Table 1 – Microphone Array Geometry Semantics
| Label | Size | Description |
| HEADER | 9 Bytes | |
| · Standard | 7 Bytes | The CAE-MAG string |
| · Version | 1 Byte | Major MPAI-CAE version |
| · Subversion | 1 Byte | Minor MPAI-CAE version |
| MAGID | 16 Bytes | UUID Identifier of the Microphone Array Geometry. |
| Microphone features | ||
| · ArrayType | bit 0-1 | Indicates the type of microphone array positioning such as 00:Spherical, 01:Circular, 10:Planar, 11:Linear. (uint8) |
| · ArrayScat | bit 2 | Indicates the type of the microphone array (0:Rigid, 1:Open). (uint8) |
| · Reserved | bit 2-7 | |
| · ArrayFilterURI | N Bytes | A uniform resource identifier (URI) string identifying the path to a local or remote file containing specific filter coefficients of the microphone array to be used for equalisation. (string) |
| Sampling features | ||
| · SamplingRate | 0-3 bits | 0:8, 1:16, 2:24, 3:32, 4:44.1, 5:48, 6: 64, 7: 96, 8: 192 (all kHz) |
| · SampleType | 4-6 bits | (aka sample precision) 0:8, 1:16, 2:24, 3:32, 4:64 (bits/sample) |
| · Reserved | bit 7 | |
| BlockSize | 4 Bytes | Minimum BlockSize: ≥ 256. |
| NumberOfMicrophones | 1 Byte | |
| MicrophoneAttributes | A list containing Microphone attributes. | |
| · MicrophoneID | 1 Byte | |
| · xCoord | 4 Bytes | x position of the microphone in m. (number) |
| · yCoord | 4 Bytes | y position of the microphone in m.(number) |
| · zCoord | 4 Bytes | z position of the microphone in m. (number) |
| · directivity | bit 0-2 | The directivity pattern of the specific microphone, 000: omnidirectional, 001: figure of eight, 010: cardioid, 011: supercardioid, 100: hypercardioid (uint8) |
| · Reserved | Bit 3-7 | |
| · Channel map | 1 Byte | Indicates the number of Audio channel |
| · micxLookCoord | 4 Bytes | x component of the vector representing the look direction of the microphone in m. (number) |
| · micyLookCoord | 4 Bytes | y component of the vector representing the look direction of the microphone in m. (number) |
| · miczLookCoord | 4 Bytes | z component of the vector representing the look direction of the microphone. (number) |
| MicrophoneArrayLookCoord | ||
| xLookCoord | 4 Bytes | x component of the vector representing the look direction of the microphone array. (number) |
| yLookCoord | 4 Bytes | y component of the vector representing the look direction of the microphone array. (number) |
| zLookCoord | 4 Bytes | z component of the vector representing the look direction of the microphone array. (number) |
