diff options
Diffstat (limited to 'src/audio_core/codec.cpp')
| -rw-r--r-- | src/audio_core/codec.cpp | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/src/audio_core/codec.cpp b/src/audio_core/codec.cpp index 3e23323f1..c7efae753 100644 --- a/src/audio_core/codec.cpp +++ b/src/audio_core/codec.cpp | |||
| @@ -15,22 +15,25 @@ | |||
| 15 | 15 | ||
| 16 | namespace Codec { | 16 | namespace Codec { |
| 17 | 17 | ||
| 18 | StereoBuffer16 DecodeADPCM(const u8* const data, const size_t sample_count, const std::array<s16, 16>& adpcm_coeff, ADPCMState& state) { | 18 | StereoBuffer16 DecodeADPCM(const u8* const data, const size_t sample_count, |
| 19 | const std::array<s16, 16>& adpcm_coeff, ADPCMState& state) { | ||
| 19 | // GC-ADPCM with scale factor and variable coefficients. | 20 | // GC-ADPCM with scale factor and variable coefficients. |
| 20 | // Frames are 8 bytes long containing 14 samples each. | 21 | // Frames are 8 bytes long containing 14 samples each. |
| 21 | // Samples are 4 bits (one nibble) long. | 22 | // Samples are 4 bits (one nibble) long. |
| 22 | 23 | ||
| 23 | constexpr size_t FRAME_LEN = 8; | 24 | constexpr size_t FRAME_LEN = 8; |
| 24 | constexpr size_t SAMPLES_PER_FRAME = 14; | 25 | constexpr size_t SAMPLES_PER_FRAME = 14; |
| 25 | constexpr std::array<int, 16> SIGNED_NIBBLES {{ 0, 1, 2, 3, 4, 5, 6, 7, -8, -7, -6, -5, -4, -3, -2, -1 }}; | 26 | constexpr std::array<int, 16> SIGNED_NIBBLES{ |
| 27 | {0, 1, 2, 3, 4, 5, 6, 7, -8, -7, -6, -5, -4, -3, -2, -1}}; | ||
| 26 | 28 | ||
| 27 | const size_t ret_size = sample_count % 2 == 0 ? sample_count : sample_count + 1; // Ensure multiple of two. | 29 | const size_t ret_size = |
| 30 | sample_count % 2 == 0 ? sample_count : sample_count + 1; // Ensure multiple of two. | ||
| 28 | StereoBuffer16 ret(ret_size); | 31 | StereoBuffer16 ret(ret_size); |
| 29 | 32 | ||
| 30 | int yn1 = state.yn1, | 33 | int yn1 = state.yn1, yn2 = state.yn2; |
| 31 | yn2 = state.yn2; | ||
| 32 | 34 | ||
| 33 | const size_t NUM_FRAMES = (sample_count + (SAMPLES_PER_FRAME - 1)) / SAMPLES_PER_FRAME; // Round up. | 35 | const size_t NUM_FRAMES = |
| 36 | (sample_count + (SAMPLES_PER_FRAME - 1)) / SAMPLES_PER_FRAME; // Round up. | ||
| 34 | for (size_t framei = 0; framei < NUM_FRAMES; framei++) { | 37 | for (size_t framei = 0; framei < NUM_FRAMES; framei++) { |
| 35 | const int frame_header = data[framei * FRAME_LEN]; | 38 | const int frame_header = data[framei * FRAME_LEN]; |
| 36 | const int scale = 1 << (frame_header & 0xF); | 39 | const int scale = 1 << (frame_header & 0xF); |
| @@ -43,7 +46,8 @@ StereoBuffer16 DecodeADPCM(const u8* const data, const size_t sample_count, cons | |||
| 43 | // Decodes an audio sample. One nibble produces one sample. | 46 | // Decodes an audio sample. One nibble produces one sample. |
| 44 | const auto decode_sample = [&](const int nibble) -> s16 { | 47 | const auto decode_sample = [&](const int nibble) -> s16 { |
| 45 | const int xn = nibble * scale; | 48 | const int xn = nibble * scale; |
| 46 | // We first transform everything into 11 bit fixed point, perform the second order digital filter, then transform back. | 49 | // We first transform everything into 11 bit fixed point, perform the second order |
| 50 | // digital filter, then transform back. | ||
| 47 | // 0x400 == 0.5 in 11 bit fixed point. | 51 | // 0x400 == 0.5 in 11 bit fixed point. |
| 48 | // Filter: y[n] = x[n] + 0.5 + c1 * y[n-1] + c2 * y[n-2] | 52 | // Filter: y[n] = x[n] + 0.5 + c1 * y[n-1] + c2 * y[n-2] |
| 49 | int val = ((xn << 11) + 0x400 + coef1 * yn1 + coef2 * yn2) >> 11; | 53 | int val = ((xn << 11) + 0x400 + coef1 * yn1 + coef2 * yn2) >> 11; |
| @@ -82,7 +86,8 @@ static s16 SignExtendS8(u8 x) { | |||
| 82 | return static_cast<s16>(static_cast<s8>(x)); | 86 | return static_cast<s16>(static_cast<s8>(x)); |
| 83 | } | 87 | } |
| 84 | 88 | ||
| 85 | StereoBuffer16 DecodePCM8(const unsigned num_channels, const u8* const data, const size_t sample_count) { | 89 | StereoBuffer16 DecodePCM8(const unsigned num_channels, const u8* const data, |
| 90 | const size_t sample_count) { | ||
| 86 | ASSERT(num_channels == 1 || num_channels == 2); | 91 | ASSERT(num_channels == 1 || num_channels == 2); |
| 87 | 92 | ||
| 88 | StereoBuffer16 ret(sample_count); | 93 | StereoBuffer16 ret(sample_count); |
| @@ -101,7 +106,8 @@ StereoBuffer16 DecodePCM8(const unsigned num_channels, const u8* const data, con | |||
| 101 | return ret; | 106 | return ret; |
| 102 | } | 107 | } |
| 103 | 108 | ||
| 104 | StereoBuffer16 DecodePCM16(const unsigned num_channels, const u8* const data, const size_t sample_count) { | 109 | StereoBuffer16 DecodePCM16(const unsigned num_channels, const u8* const data, |
| 110 | const size_t sample_count) { | ||
| 105 | ASSERT(num_channels == 1 || num_channels == 2); | 111 | ASSERT(num_channels == 1 || num_channels == 2); |
| 106 | 112 | ||
| 107 | StereoBuffer16 ret(sample_count); | 113 | StereoBuffer16 ret(sample_count); |
| @@ -118,5 +124,4 @@ StereoBuffer16 DecodePCM16(const unsigned num_channels, const u8* const data, co | |||
| 118 | 124 | ||
| 119 | return ret; | 125 | return ret; |
| 120 | } | 126 | } |
| 121 | |||
| 122 | }; | 127 | }; |