Alc/ambidefs.h

   1 #ifndef AMBIDEFS_H
   2 #define AMBIDEFS_H
   3
   4 #include <array>
   5
   6 /* The maximum number of Ambisonics coefficients. For a given order (o), the
   7  * size needed will be (o+1)**2, thus zero-order has 1, first-order has 4,
   8  * second-order has 9, third-order has 16, and fourth-order has 25.
   9  */
  10 #define MAX_AMBI_ORDER  3
  11 #define MAX_AMBI_COEFFS ((MAX_AMBI_ORDER+1) * (MAX_AMBI_ORDER+1))
  12
  13 /* A bitmask of ambisonic channels for 0 to 4th order. This only specifies up
  14  * to 4th order, which is the highest order a 32-bit mask value can specify (a
  15  * 64-bit mask could handle up to 7th order).
  16  */
  17 #define AMBI_0ORDER_MASK 0x00000001
  18 #define AMBI_1ORDER_MASK 0x0000000f
  19 #define AMBI_2ORDER_MASK 0x000001ff
  20 #define AMBI_3ORDER_MASK 0x0000ffff
  21 #define AMBI_4ORDER_MASK 0x01ffffff
  22
  23 /* A bitmask of ambisonic channels with height information. If none of these
  24  * channels are used/needed, there's no height (e.g. with most surround sound
  25  * speaker setups). This is ACN ordering, with bit 0 being ACN 0, etc.
  26  */
  27 #define AMBI_PERIPHONIC_MASK (0xfe7ce4)
  28
  29 /* The maximum number of Ambisonic coefficients for 2D (non-periphonic)
  30  * representation. This is 2 per each order above zero-order, plus 1 for zero-
  31  * order. Or simply, o*2 + 1.
  32  */
  33 #define MAX_AMBI2D_COEFFS (MAX_AMBI_ORDER*2 + 1)
  34
  35
  36 /* NOTE: These are scale factors as applied to Ambisonics content. Decoder
  37  * coefficients should be divided by these values to get proper scalings.
  38  */
  39 struct AmbiScale {
  40     static constexpr std::array<float,MAX_AMBI_COEFFS> FromN3D{{
  41         1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
  42         1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f
  43     }};
  44     static constexpr std::array<float,MAX_AMBI_COEFFS> FromSN3D{{
  45         1.000000000f, /* ACN  0, sqrt(1) */
  46         1.732050808f, /* ACN  1, sqrt(3) */
  47         1.732050808f, /* ACN  2, sqrt(3) */
  48         1.732050808f, /* ACN  3, sqrt(3) */
  49         2.236067978f, /* ACN  4, sqrt(5) */
  50         2.236067978f, /* ACN  5, sqrt(5) */
  51         2.236067978f, /* ACN  6, sqrt(5) */
  52         2.236067978f, /* ACN  7, sqrt(5) */
  53         2.236067978f, /* ACN  8, sqrt(5) */
  54         2.645751311f, /* ACN  9, sqrt(7) */
  55         2.645751311f, /* ACN 10, sqrt(7) */
  56         2.645751311f, /* ACN 11, sqrt(7) */
  57         2.645751311f, /* ACN 12, sqrt(7) */
  58         2.645751311f, /* ACN 13, sqrt(7) */
  59         2.645751311f, /* ACN 14, sqrt(7) */
  60         2.645751311f, /* ACN 15, sqrt(7) */
  61     }};
  62     static constexpr std::array<float,MAX_AMBI_COEFFS> FromFuMa{{
  63         1.414213562f, /* ACN  0 (W), sqrt(2) */
  64         1.732050808f, /* ACN  1 (Y), sqrt(3) */
  65         1.732050808f, /* ACN  2 (Z), sqrt(3) */
  66         1.732050808f, /* ACN  3 (X), sqrt(3) */
  67         1.936491673f, /* ACN  4 (V), sqrt(15)/2 */
  68         1.936491673f, /* ACN  5 (T), sqrt(15)/2 */
  69         2.236067978f, /* ACN  6 (R), sqrt(5) */
  70         1.936491673f, /* ACN  7 (S), sqrt(15)/2 */
  71         1.936491673f, /* ACN  8 (U), sqrt(15)/2 */
  72         2.091650066f, /* ACN  9 (Q), sqrt(35/8) */
  73         1.972026594f, /* ACN 10 (O), sqrt(35)/3 */
  74         2.231093404f, /* ACN 11 (M), sqrt(224/45) */
  75         2.645751311f, /* ACN 12 (K), sqrt(7) */
  76         2.231093404f, /* ACN 13 (L), sqrt(224/45) */
  77         1.972026594f, /* ACN 14 (N), sqrt(35)/3 */
  78         2.091650066f, /* ACN 15 (P), sqrt(35/8) */
  79     }};
  80 };
  81
  82 struct AmbiIndex {
  83     static constexpr std::array<int,MAX_AMBI_COEFFS> FromFuMa{{
  84         0,  /* W */
  85         3,  /* X */
  86         1,  /* Y */
  87         2,  /* Z */
  88         6,  /* R */
  89         7,  /* S */
  90         5,  /* T */
  91         8,  /* U */
  92         4,  /* V */
  93         12, /* K */
  94         13, /* L */
  95         11, /* M */
  96         14, /* N */
  97         10, /* O */
  98         15, /* P */
  99         9,  /* Q */
 100     }};
 101     static constexpr std::array<int,MAX_AMBI_COEFFS> FromACN{{
 102         0,  1,  2,  3,  4,  5,  6,  7,
 103         8,  9, 10, 11, 12, 13, 14, 15
 104     }};
 105
 106     static constexpr std::array<int,MAX_AMBI2D_COEFFS> From2D{{
 107         0, 1,3, 4,8, 9,15
 108     }};
 109     static constexpr std::array<int,MAX_AMBI_COEFFS> From3D{{
 110         0,  1,  2,  3,  4,  5,  6,  7,
 111         8,  9, 10, 11, 12, 13, 14, 15
 112     }};
 113 };
 114
 115 #endif /* AMBIDEFS_H */