audio_core: Port codec code from Citra for ADPCM decoding.

This commit is contained in:
bunnei 2018-08-03 15:30:01 -04:00
parent 02fccc0940
commit f1cb3903ac
5 changed files with 126 additions and 11 deletions

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@ -4,6 +4,8 @@ add_library(audio_core STATIC
buffer.h
cubeb_sink.cpp
cubeb_sink.h
codec.cpp
codec.h
null_sink.h
stream.cpp
stream.h

77
src/audio_core/codec.cpp Normal file
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@ -0,0 +1,77 @@
// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <algorithm>
#include "audio_core/codec.h"
namespace AudioCore::Codec {
std::vector<s16> DecodeADPCM(const u8* const data, size_t size, const ADPCM_Coeff& coeff,
ADPCMState& state) {
// GC-ADPCM with scale factor and variable coefficients.
// Frames are 8 bytes long containing 14 samples each.
// Samples are 4 bits (one nibble) long.
constexpr size_t FRAME_LEN = 8;
constexpr size_t SAMPLES_PER_FRAME = 14;
constexpr std::array<int, 16> SIGNED_NIBBLES = {
{0, 1, 2, 3, 4, 5, 6, 7, -8, -7, -6, -5, -4, -3, -2, -1}};
const size_t sample_count = (size / FRAME_LEN) * SAMPLES_PER_FRAME;
const size_t ret_size =
sample_count % 2 == 0 ? sample_count : sample_count + 1; // Ensure multiple of two.
std::vector<s16> ret(ret_size);
int yn1 = state.yn1, yn2 = state.yn2;
const size_t NUM_FRAMES =
(sample_count + (SAMPLES_PER_FRAME - 1)) / SAMPLES_PER_FRAME; // Round up.
for (size_t framei = 0; framei < NUM_FRAMES; framei++) {
const int frame_header = data[framei * FRAME_LEN];
const int scale = 1 << (frame_header & 0xF);
const int idx = (frame_header >> 4) & 0x7;
// Coefficients are fixed point with 11 bits fractional part.
const int coef1 = coeff[idx * 2 + 0];
const int coef2 = coeff[idx * 2 + 1];
// Decodes an audio sample. One nibble produces one sample.
const auto decode_sample = [&](const int nibble) -> s16 {
const int xn = nibble * scale;
// We first transform everything into 11 bit fixed point, perform the second order
// digital filter, then transform back.
// 0x400 == 0.5 in 11 bit fixed point.
// Filter: y[n] = x[n] + 0.5 + c1 * y[n-1] + c2 * y[n-2]
int val = ((xn << 11) + 0x400 + coef1 * yn1 + coef2 * yn2) >> 11;
// Clamp to output range.
val = std::clamp<s32>(val, -32768, 32767);
// Advance output feedback.
yn2 = yn1;
yn1 = val;
return static_cast<s16>(val);
};
size_t outputi = framei * SAMPLES_PER_FRAME;
size_t datai = framei * FRAME_LEN + 1;
for (size_t i = 0; i < SAMPLES_PER_FRAME && outputi < sample_count; i += 2) {
const s16 sample1 = decode_sample(SIGNED_NIBBLES[data[datai] >> 4]);
ret[outputi] = sample1;
outputi++;
const s16 sample2 = decode_sample(SIGNED_NIBBLES[data[datai] & 0xF]);
ret[outputi] = sample2;
outputi++;
datai++;
}
}
state.yn1 = yn1;
state.yn2 = yn2;
return ret;
}
} // namespace AudioCore::Codec

44
src/audio_core/codec.h Normal file
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@ -0,0 +1,44 @@
// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <array>
#include <vector>
#include "common/common_types.h"
namespace AudioCore::Codec {
enum class PcmFormat : u32 {
Invalid = 0,
Int8 = 1,
Int16 = 2,
Int24 = 3,
Int32 = 4,
PcmFloat = 5,
Adpcm = 6,
};
/// See: Codec::DecodeADPCM
struct ADPCMState {
// Two historical samples from previous processed buffer,
// required for ADPCM decoding
s16 yn1; ///< y[n-1]
s16 yn2; ///< y[n-2]
};
using ADPCM_Coeff = std::array<s16, 16>;
/**
* @param data Pointer to buffer that contains ADPCM data to decode
* @param size Size of buffer in bytes
* @param coeff ADPCM coefficients
* @param state ADPCM state, this is updated with new state
* @return Decoded stereo signed PCM16 data, sample_count in length
*/
std::vector<s16> DecodeADPCM(const u8* const data, size_t size, const ADPCM_Coeff& coeff,
ADPCMState& state);
}; // namespace AudioCore::Codec

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@ -4,6 +4,8 @@
#include <array>
#include <vector>
#include "audio_core/codec.h"
#include "common/logging/log.h"
#include "core/core.h"
#include "core/hle/ipc_helpers.h"
@ -200,7 +202,7 @@ void AudOutU::OpenAudioOutImpl(Kernel::HLERequestContext& ctx) {
rb.Push(RESULT_SUCCESS);
rb.Push<u32>(DefaultSampleRate);
rb.Push<u32>(params.channel_count);
rb.Push<u32>(static_cast<u32>(PcmFormat::Int16));
rb.Push<u32>(static_cast<u32>(AudioCore::Codec::PcmFormat::Int16));
rb.Push<u32>(static_cast<u32>(AudioState::Stopped));
rb.PushIpcInterface<Audio::IAudioOut>(audio_out_interface);
}

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@ -38,16 +38,6 @@ private:
void ListAudioOutsImpl(Kernel::HLERequestContext& ctx);
void OpenAudioOutImpl(Kernel::HLERequestContext& ctx);
enum class PcmFormat : u32 {
Invalid = 0,
Int8 = 1,
Int16 = 2,
Int24 = 3,
Int32 = 4,
PcmFloat = 5,
Adpcm = 6,
};
};
} // namespace Service::Audio