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diff --git a/src/multimedia/spatial/qambisonicdecoder.cpp b/src/multimedia/spatial/qambisonicdecoder.cpp
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-/****************************************************************************
-**
-** Copyright (C) 2022 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-#include "qambisonicdecoder_p.h"
-
-#include "qambisonicdecoderdata_p.h"
-#include <cmath>
-
-QT_BEGIN_NAMESPACE
-
-// Ambisonic decoding is described in detail in https://ambisonics.dreamhosters.com/BLaH3.pdf.
-// We're using a phase matched band splitting filter to split the ambisonic signal into a low
-// and high frequency component and apply matrix conversions to those components individually
-// as described in the document.
-//
-// We are currently not using a near field compensation filter, something that could potentially
-// improve sound quality further.
-
-
-struct QAmbisonicDecoderData
-{
- QAudioFormat::ChannelConfig config;
- const float *lf[3];
- const float *hf[3];
-};
-
-static const QAmbisonicDecoderData decoderMap[] =
-{
- { QAudioFormat::ChannelConfigMono,
- { decoderMatrix_mono_1_lf, decoderMatrix_mono_2_lf, decoderMatrix_mono_3_lf },
- { decoderMatrix_mono_1_hf, decoderMatrix_mono_2_hf, decoderMatrix_mono_3_hf }
- },
- { QAudioFormat::ChannelConfigStereo,
- { decoderMatrix_stereo_1_lf, decoderMatrix_stereo_2_lf, decoderMatrix_stereo_3_lf },
- { decoderMatrix_stereo_1_hf, decoderMatrix_stereo_2_hf, decoderMatrix_stereo_3_hf }
- },
- { QAudioFormat::ChannelConfig2Dot1,
- { decoderMatrix_2dot1_1_lf, decoderMatrix_2dot1_2_lf, decoderMatrix_2dot1_3_lf },
- { decoderMatrix_2dot1_1_hf, decoderMatrix_2dot1_2_hf, decoderMatrix_2dot1_3_hf }
- },
- { QAudioFormat::ChannelConfigSurround5Dot0,
- { decoderMatrix_5dot0_1_lf, decoderMatrix_5dot0_2_lf, decoderMatrix_5dot0_3_lf },
- { decoderMatrix_5dot0_1_hf, decoderMatrix_5dot0_2_hf, decoderMatrix_5dot0_3_hf }
- },
- { QAudioFormat::ChannelConfigSurround5Dot1,
- { decoderMatrix_5dot1_1_lf, decoderMatrix_5dot1_2_lf, decoderMatrix_5dot1_3_lf },
- { decoderMatrix_5dot1_1_hf, decoderMatrix_5dot1_2_hf, decoderMatrix_5dot1_3_hf }
- },
- { QAudioFormat::ChannelConfigSurround7Dot0,
- { decoderMatrix_7dot0_1_lf, decoderMatrix_7dot0_2_lf, decoderMatrix_7dot0_3_lf },
- { decoderMatrix_7dot0_1_hf, decoderMatrix_7dot0_2_hf, decoderMatrix_7dot0_3_hf }
- },
- { QAudioFormat::ChannelConfigSurround7Dot1,
- { decoderMatrix_7dot1_1_lf, decoderMatrix_7dot1_2_lf, decoderMatrix_7dot1_3_lf },
- { decoderMatrix_7dot1_1_hf, decoderMatrix_7dot1_2_hf, decoderMatrix_7dot1_3_hf }
- }
-};
-
-
-// Implements a split second order IIR filter
-// The audio data is split into a phase synced low and high frequency part
-// This allows us to apply different factors to both parts for better sound
-// localization when converting from ambisonic formats
-//
-// Details are described in https://ambisonics.dreamhosters.com/BLaH3.pdf, Appendix A.2.
-class QAmbisonicDecoderFilter
-{
-public:
- QAmbisonicDecoderFilter() = default;
- void configure(float sampleRate, float cutoffFrequency = 380)
- {
- double k = tan(M_PI*cutoffFrequency/sampleRate);
- a1 = float(2.*(k*k - 1.)/(k*k + 2*k + 1.));
- a2 = float((k*k - 2*k + 1.)/(k*k + 2*k + 1.));
-
- b0_lf = float(k*k/(k*k + 2*k + 1));
- b1_lf = 2.f*b0_lf;
-
- b0_hf = float(1./(k*k + 2*k + 1));
- b1_hf = -2.f*b0_hf;
- }
-
- struct Output
- {
- float lf;
- float hf;
- };
-
- Output next(float x)
- {
- float r_lf = x*b0_lf +
- prevX[0]*b1_lf +
- prevX[1]*b0_lf -
- prevR_lf[0]*a1 -
- prevR_lf[1]*a2;
- float r_hf = x*b0_hf +
- prevX[0]*b1_hf +
- prevX[1]*b0_hf -
- prevR_hf[0]*a1 -
- prevR_hf[1]*a2;
- prevX[1] = prevX[0];
- prevX[0] = x;
- prevR_lf[1] = prevR_lf[0];
- prevR_lf[0] = r_lf;
- prevR_hf[1] = prevR_hf[0];
- prevR_hf[0] = r_hf;
- return { r_lf, r_hf };
- }
-
-private:
- float a1 = 0.;
- float a2 = 0.;
-
- float b0_hf = 0.;
- float b1_hf = 0.;
-
- float b0_lf = 0.;
- float b1_lf = 0.;
-
- float prevX[2] = {};
- float prevR_lf[2] = {};
- float prevR_hf[2] = {};
-};
-
-
-QAmbisonicDecoder::QAmbisonicDecoder(AmbisonicLevel ambisonicLevel, const QAudioFormat &format)
- : level(ambisonicLevel)
-{
- auto outputConfiguration = format.channelConfig();
- if (outputConfiguration == QAudioFormat::ChannelConfigUnknown)
- outputConfiguration = format.defaultChannelConfigForChannelCount(format.channelCount());
- for (const auto &d : decoderMap) {
- if (d.config == outputConfiguration) {
- decoderData = &d;
- break;
- }
- }
- if (!decoderData) {
- // ### FIXME: use a stereo config, fill other channels with 0
- }
-
- inputChannels = (level+1)*(level+1);
- outputChannels = format.channelCount();
-
- filters = new QAmbisonicDecoderFilter[inputChannels];
- for (int i = 0; i < inputChannels; ++i)
- filters[i].configure(format.sampleRate());
-}
-
-void QAmbisonicDecoder::processBuffer(const float *input[], float *output, int nSamples)
-{
- float *o = output;
- memset(o, 0, nSamples*outputChannels*sizeof(float));
-
- const float *matrix_hi = decoderData->hf[level];
- const float *matrix_lo = decoderData->hf[level];
- for (int i = 0; i < nSamples; ++i) {
- QAmbisonicDecoderFilter::Output buf[maxAmbisonicChannels];
- for (int j = 0; j < inputChannels; ++j)
- buf[j] = filters[j].next(input[j][i]);
- for (int j = 0; j < inputChannels; ++j) {
- for (int k = 0; k < outputChannels; ++k)
- o[k] += matrix_lo[k*outputChannels + j]*buf[j].lf + matrix_hi[k*outputChannels + j]*buf[j].hf;
- }
- o += outputChannels;
- }
-}
-
-void QAmbisonicDecoder::processBuffer(const float *input[], short *output, int nSamples)
-{
- if (level == 0) {
- // ### copy W data
- return;
- }
- const float *matrix_hi = decoderData->hf[level - 1];
- const float *matrix_lo = decoderData->hf[level - 1];
- for (int i = 0; i < nSamples; ++i) {
- QAmbisonicDecoderFilter::Output buf[maxAmbisonicChannels];
- for (int j = 0; j < inputChannels; ++j)
- buf[j] = filters[j].next(input[j][i]);
- float o[32]; // we can't support more than 32 channels from our API
- memset(o, 0, 32*sizeof(short));
- for (int j = 0; j < inputChannels; ++j) {
- for (int k = 0; k < outputChannels; ++k)
- o[k] += matrix_lo[k*outputChannels + j]*buf[j].lf + matrix_hi[k*outputChannels + j]*buf[j].hf;
- }
- for (int k = 0; k < outputChannels; ++k)
- output[k] = static_cast<short>(o[k]*32768.);
- output += outputChannels;
- }
-}
-
-QT_END_NAMESPACE
-
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