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119 lines
4.2 KiB
119 lines
4.2 KiB
#ifndef AMBIDEFS_H
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#define AMBIDEFS_H
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#include <array>
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/* The maximum number of Ambisonics channels. For a given order (o), the size
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* needed will be (o+1)**2, thus zero-order has 1, first-order has 4, second-
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* order has 9, third-order has 16, and fourth-order has 25.
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*/
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#define MAX_AMBI_ORDER 3
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constexpr inline size_t AmbiChannelsFromOrder(size_t order) noexcept
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{ return (order+1) * (order+1); }
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#define MAX_AMBI_CHANNELS AmbiChannelsFromOrder(MAX_AMBI_ORDER)
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/* A bitmask of ambisonic channels for 0 to 4th order. This only specifies up
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* to 4th order, which is the highest order a 32-bit mask value can specify (a
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* 64-bit mask could handle up to 7th order).
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*/
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#define AMBI_0ORDER_MASK 0x00000001
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#define AMBI_1ORDER_MASK 0x0000000f
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#define AMBI_2ORDER_MASK 0x000001ff
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#define AMBI_3ORDER_MASK 0x0000ffff
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#define AMBI_4ORDER_MASK 0x01ffffff
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/* A bitmask of ambisonic channels with height information. If none of these
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* channels are used/needed, there's no height (e.g. with most surround sound
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* speaker setups). This is ACN ordering, with bit 0 being ACN 0, etc.
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*/
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#define AMBI_PERIPHONIC_MASK (0xfe7ce4)
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/* The maximum number of ambisonic channels for 2D (non-periphonic)
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* representation. This is 2 per each order above zero-order, plus 1 for zero-
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* order. Or simply, o*2 + 1.
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*/
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constexpr inline size_t Ambi2DChannelsFromOrder(size_t order) noexcept
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{ return order*2 + 1; }
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#define MAX_AMBI2D_CHANNELS Ambi2DChannelsFromOrder(MAX_AMBI_ORDER)
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/* NOTE: These are scale factors as applied to Ambisonics content. Decoder
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* coefficients should be divided by these values to get proper scalings.
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*/
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struct AmbiScale {
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static constexpr std::array<float,MAX_AMBI_CHANNELS> FromN3D{{
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1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
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1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f
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}};
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static constexpr std::array<float,MAX_AMBI_CHANNELS> FromSN3D{{
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1.000000000f, /* ACN 0, sqrt(1) */
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1.732050808f, /* ACN 1, sqrt(3) */
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1.732050808f, /* ACN 2, sqrt(3) */
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1.732050808f, /* ACN 3, sqrt(3) */
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2.236067978f, /* ACN 4, sqrt(5) */
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2.236067978f, /* ACN 5, sqrt(5) */
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2.236067978f, /* ACN 6, sqrt(5) */
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2.236067978f, /* ACN 7, sqrt(5) */
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2.236067978f, /* ACN 8, sqrt(5) */
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2.645751311f, /* ACN 9, sqrt(7) */
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2.645751311f, /* ACN 10, sqrt(7) */
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2.645751311f, /* ACN 11, sqrt(7) */
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2.645751311f, /* ACN 12, sqrt(7) */
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2.645751311f, /* ACN 13, sqrt(7) */
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2.645751311f, /* ACN 14, sqrt(7) */
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2.645751311f, /* ACN 15, sqrt(7) */
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}};
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static constexpr std::array<float,MAX_AMBI_CHANNELS> FromFuMa{{
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1.414213562f, /* ACN 0 (W), sqrt(2) */
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1.732050808f, /* ACN 1 (Y), sqrt(3) */
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1.732050808f, /* ACN 2 (Z), sqrt(3) */
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1.732050808f, /* ACN 3 (X), sqrt(3) */
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1.936491673f, /* ACN 4 (V), sqrt(15)/2 */
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1.936491673f, /* ACN 5 (T), sqrt(15)/2 */
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2.236067978f, /* ACN 6 (R), sqrt(5) */
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1.936491673f, /* ACN 7 (S), sqrt(15)/2 */
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1.936491673f, /* ACN 8 (U), sqrt(15)/2 */
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2.091650066f, /* ACN 9 (Q), sqrt(35/8) */
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1.972026594f, /* ACN 10 (O), sqrt(35)/3 */
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2.231093404f, /* ACN 11 (M), sqrt(224/45) */
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2.645751311f, /* ACN 12 (K), sqrt(7) */
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2.231093404f, /* ACN 13 (L), sqrt(224/45) */
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1.972026594f, /* ACN 14 (N), sqrt(35)/3 */
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2.091650066f, /* ACN 15 (P), sqrt(35/8) */
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}};
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};
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struct AmbiIndex {
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static constexpr std::array<int,MAX_AMBI_CHANNELS> FromFuMa{{
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0, /* W */
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3, /* X */
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1, /* Y */
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2, /* Z */
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6, /* R */
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7, /* S */
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5, /* T */
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8, /* U */
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4, /* V */
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12, /* K */
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13, /* L */
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11, /* M */
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14, /* N */
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10, /* O */
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15, /* P */
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9, /* Q */
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}};
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static constexpr std::array<int,MAX_AMBI_CHANNELS> FromACN{{
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0, 1, 2, 3, 4, 5, 6, 7,
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8, 9, 10, 11, 12, 13, 14, 15
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}};
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static constexpr std::array<int,MAX_AMBI2D_CHANNELS> From2D{{
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0, 1,3, 4,8, 9,15
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}};
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static constexpr std::array<int,MAX_AMBI_CHANNELS> From3D{{
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0, 1, 2, 3, 4, 5, 6, 7,
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8, 9, 10, 11, 12, 13, 14, 15
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}};
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};
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#endif /* AMBIDEFS_H */
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