| commit | author | age | ||
| 791513 | 1 | ;Authors: A. Nguyen, 2025. |
| AN | 2 | |
| 3 | ; Design limitations: | |
| 4 | ; 1) Sounds must have identical sample rate; otherwise, SoX fails silently, literally. | |
| 5 | ||
| 6 | ; Questions: | |
| 7 | ; 1) Is there a built-in (flatten lst)-function? | |
| 8 | ; 2) Implement up to which order? <=> CLI issues to be expected (e.g., maximum command character length)? | |
| 9 | ||
| 10 | (in-package :om) | |
| 11 | ||
| 12 | ;;; SOX-HOAENCODE ======================== | |
| 13 | ||
| 14 | ; Util | |
| 15 | (defun flatten (structure) | |
| 16 | (cond | |
| 17 | ((null structure) | |
| 18 | nil) | |
| 19 | ((atom structure) | |
| 20 | (list structure)) | |
| 21 | (t | |
| 22 | (mapcan #'flatten structure)) | |
| 23 | ) | |
| 24 | ) | |
| 25 | ||
| 26 | (defun sox-hoaencode-deg-to-rad (x) | |
| 27 | (* (/ x 180) pi) | |
| 28 | ) | |
| 29 | ||
| 30 | (defun sox-hoaencode-double-to-float (lst) | |
| 31 | (mapcar | |
| 32 | (lambda (x) (float x 0.0S0)) | |
| 33 | lst | |
| 34 | ) | |
| 35 | ) | |
| 36 | ||
| 37 | ; Ambisonics | |
| 38 | (defun sox-hoaencode-sn3d-factor (order degree) | |
| 39 | (ecase order | |
| 40 | (0 1) | |
| 41 | (1 1) | |
| 42 | (2 | |
| 43 | (ecase (abs degree) | |
| 44 | (2 (/ (sqrt 3) 6)) | |
| 45 | (1 (/ (sqrt 3) 3)) | |
| 46 | (0 1) | |
| 47 | )) | |
| 48 | (3 | |
| 49 | (ecase (abs degree) | |
| 50 | (3 (/ (sqrt 10) 60)) | |
| 51 | (2 (/ (sqrt 15) 30)) | |
| 52 | (1 (/ (sqrt 6) 6)) | |
| 53 | (0 1) | |
| 54 | ) | |
| 55 | ) | |
| 56 | ) | |
| 57 | ) | |
| 58 | ||
| 59 | (defun sox-hoaencode-azimuth-factor (degree theta_deg) | |
| 60 | (let* | |
| 61 | ( | |
| 62 | (theta (sox-hoaencode-deg-to-rad theta_deg)) | |
| 63 | ) | |
| 64 | (if (< degree 0) | |
| 65 | (sin (* (abs degree) theta)) | |
| 66 | (cos (* (abs degree) theta)) | |
| 67 | ) | |
| 68 | ) | |
| 69 | ) | |
| 70 | ||
| 71 | (defun sox-hoaencode-elevation-factor (order degree phi_deg) | |
| 72 | (let* | |
| 73 | ( | |
| 74 | (phi (sox-hoaencode-deg-to-rad phi_deg)) | |
| 75 | ) | |
| 76 | (ecase order | |
| 77 | (0 1) | |
| 78 | (1 | |
| 79 | (ecase (abs degree) | |
| 80 | (0 (sin phi)) | |
| 81 | (1 (cos phi)) | |
| 82 | )) | |
| 83 | (2 | |
| 84 | (ecase (abs degree) | |
| 85 | (0 (- (/ (* 3 (expt (sin phi) 2)) 2) (/ 1 2))) | |
| 86 | (1 (/ (* 3 (expt (sin phi) 2)) 2)) | |
| 87 | (2 (* 3 (expt (cos phi) 2))) | |
| 88 | )) | |
| 89 | (3 | |
| 90 | (ecase (abs degree) | |
| 91 | (0 (/ (* (sin phi) (- (* 5 (expt (sin phi) 2)) 3)) 2)) | |
| 92 | (1 (- (* 6 (cos phi)) (/ (* 15 (expt (cos phi) 3)) 2))) | |
| 93 | (2 (* -15 (sin phi) (- (expt (sin phi) 2) 1))) | |
| 94 | (3 (* 15 (expt (cos phi) 3))) | |
| 95 | )) | |
| 96 | ) | |
| 97 | )) | |
| 98 | ||
| 99 | ; Convenience functions | |
| 100 | ||
| 101 | ; Ensures that positions are given as '((azimuth elevation) ...) (in degrees), i.e. | |
| 102 | ; 1) if list of list of three values, input is assumed to be '(x y z) coordinates and will be transformed to '(azimuth elevation) coordinates (in the navigational spherical coordinate system). | |
| 103 | ; 2) if list of list of two values, input is assumed to be '(azimuth elevation) coordinates and won't be transformed any further. | |
| 104 | ; 3) if 3dc, input is transformed to '(azimuth elevation) coordinates. | |
| 105 | (defun sox-hoaencode-auto-convert-positions (positions) | |
| 106 | (cond | |
| 107 | ((subtypep (type-of positions) '3dc) | |
| 108 | (progn ; convert xyz->aed, keep azimuth and elevation only. | |
| 109 | (mat-trans | |
| 110 | (butlast | |
| 111 | (mat-trans | |
| 112 | (mapcar | |
| 113 | (lambda (xyz) (multiple-value-list (om:xyz->aed (first xyz) (second xyz) (third xyz)))) | |
| 114 | (mat-trans (list (x-points positions) (y-points positions) (z-points positions))) | |
| 115 | )))))) | |
| 116 | ((subtypep (type-of positions) 'list) | |
| 117 | (cond | |
| 118 | ((= 2 (length (first positions))) | |
| 119 | positions) | |
| 120 | ((= 3 (length (first positions))) | |
| 121 | (mat-trans | |
| 122 | (butlast | |
| 123 | (mat-trans | |
| 124 | (mapcar | |
| 125 | (lambda (xyz) (multiple-value-list (om:xyz->aed (first xyz) (second xyz) (third xyz)))) | |
| 126 | positions | |
| 127 | ))))) | |
| 128 | (t (error "Input must contain lists of length 2 (ae) or 3 (xyz).")) | |
| 129 | )) | |
| 130 | (t (error "Input must be 3dc or list.")))) | |
| 131 | ||
| 132 | ; High-level API | |
| 133 | ; Returns the gain value (linear, -1 to 1) for a single ACN-channel | |
| 134 | (defun sox-hoaencode-gain-single-component (order degree azimuth_deg elevation_deg) | |
| 135 | (let | |
| 136 | ( | |
| 137 | ; It is assumed that azimuth_deg follows the implementation details of SpatDIF, | |
| 138 | ; where azimuth_deg runs counterclockwise. | |
| 139 | ; However, the formulas inside assume that azimuth_deg runs clockwise, i.e. | |
| 140 | ; the sign of azimuth_deg must be inverted. | |
| 141 | (azimuth_deg_inverted (* -1 azimuth_deg)) | |
| 142 | ) | |
| 143 | (* | |
| 144 | (sox-hoaencode-sn3d-factor order degree) | |
| 145 | (sox-hoaencode-azimuth-factor degree azimuth_deg_inverted) | |
| 146 | (sox-hoaencode-elevation-factor order degree elevation_deg))) | |
| 147 | ) | |
| 148 | ||
| 149 | ; Returns the gain values for all components at a specific order | |
| 150 | (defun sox-hoaencode-gains-by-order (order azimuth_deg elevation_deg) | |
| 151 | (loop for degree from (* -1 order) to order collect | |
| 152 | (sox-hoaencode-gain-single-component order degree azimuth_deg elevation_deg))) | |
| 153 | ||
| 154 | ; Returns the gain values for all components up to a specific order | |
| 155 | (defun sox-hoaencode-gains-up-to-order (order azimuth_deg elevation_deg) | |
| 156 | (sox-hoaencode-double-to-float | |
| 157 | (flatten | |
| 158 | (loop for ord from 0 to order collect | |
| 159 | (sox-hoaencode-gains-by-order ord azimuth_deg elevation_deg))))) | |
| 160 | ||
| 161 | ||
| 162 | (defclass! sox-hoaencode (sox-input) | |
| 163 | ( | |
| 164 | (positions :accessor positions :initarg :positions :initform nil :documentation *sox-hoaencode-positions-doc*) | |
| 165 | (order :accessor order :initarg :order :initform nil :documentation *sox-hoaencode-order-doc*) | |
| 166 | ) | |
| 167 | (:icon 100) | |
| 168 | (:documentation "Sox-hoaencode transforms <sound> into a <order>-th ambisonic (HOA) signal at <positions>. | |
| 169 | ||
| 170 | The signal follows the ambiX convention, i.e. it uses SN3D normalization and ACN channel ordering. The resulting file has (<order>+1)^2 channels (order 0: 1 channel, order 1: 4 channels, order 2: 9 channels, order 3: 16 channels, ...).") | |
| 171 | ) | |
| 172 | ||
| 173 | (defmethod initialize-instance :after ((self sox-hoaencode) &rest l) | |
| 174 | (declare (ignore l)) | |
| 175 | (when (sound self) | |
| 176 | (sox-init-sound self 'list) | |
| 177 | ) | |
| 178 | ) | |
