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187 lines
6.3 KiB
187 lines
6.3 KiB
#ifndef CORE_AMBIDEFS_H
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#define CORE_AMBIDEFS_H
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#include <array>
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#include <stddef.h>
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#include <stdint.h>
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using uint = unsigned int;
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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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constexpr uint8_t MaxAmbiOrder{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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constexpr size_t MaxAmbiChannels{AmbiChannelsFromOrder(MaxAmbiOrder)};
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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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constexpr uint Ambi0OrderMask{0x00000001};
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constexpr uint Ambi1OrderMask{0x0000000f};
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constexpr uint Ambi2OrderMask{0x000001ff};
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constexpr uint Ambi3OrderMask{0x0000ffff};
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constexpr uint Ambi4OrderMask{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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constexpr uint AmbiPeriphonicMask{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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constexpr size_t MaxAmbi2DChannels{Ambi2DChannelsFromOrder(MaxAmbiOrder)};
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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 auto& FromN3D() noexcept
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{
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static constexpr const std::array<float,MaxAmbiChannels> ret{{
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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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return ret;
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}
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static auto& FromSN3D() noexcept
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{
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static constexpr const std::array<float,MaxAmbiChannels> ret{{
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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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return ret;
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}
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static auto& FromFuMa() noexcept
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{
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static constexpr const std::array<float,MaxAmbiChannels> ret{{
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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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return ret;
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}
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static auto& FromUHJ() noexcept
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{
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static constexpr const std::array<float,MaxAmbiChannels> ret{{
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1.000000000f, /* ACN 0 (W), sqrt(1) */
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1.224744871f, /* ACN 1 (Y), sqrt(3/2) */
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1.224744871f, /* ACN 2 (Z), sqrt(3/2) */
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1.224744871f, /* ACN 3 (X), sqrt(3/2) */
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/* Higher orders not relevant for UHJ. */
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1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
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}};
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return ret;
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}
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/* Retrieves per-order HF scaling factors for "upsampling" ambisonic data. */
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static std::array<float,MaxAmbiOrder+1> GetHFOrderScales(const uint in_order,
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const uint out_order) noexcept;
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};
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struct AmbiIndex {
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static auto& FromFuMa() noexcept
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{
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static constexpr const std::array<uint8_t,MaxAmbiChannels> ret{{
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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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return ret;
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}
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static auto& FromFuMa2D() noexcept
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{
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static constexpr const std::array<uint8_t,MaxAmbi2DChannels> ret{{
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0, /* W */
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3, /* X */
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1, /* Y */
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8, /* U */
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4, /* V */
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15, /* P */
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9, /* Q */
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}};
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return ret;
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}
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static auto& FromACN() noexcept
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{
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static constexpr const std::array<uint8_t,MaxAmbiChannels> ret{{
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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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return ret;
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}
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static auto& FromACN2D() noexcept
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{
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static constexpr const std::array<uint8_t,MaxAmbi2DChannels> ret{{
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0, 1,3, 4,8, 9,15
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}};
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return ret;
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}
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static auto& OrderFromChannel() noexcept
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{
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static constexpr const std::array<uint8_t,MaxAmbiChannels> ret{{
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0, 1,1,1, 2,2,2,2,2, 3,3,3,3,3,3,3,
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}};
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return ret;
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}
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static auto& OrderFrom2DChannel() noexcept
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{
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static constexpr const std::array<uint8_t,MaxAmbi2DChannels> ret{{
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0, 1,1, 2,2, 3,3,
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}};
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return ret;
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}
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};
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#endif /* CORE_AMBIDEFS_H */
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