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    /*
     * Copyright (C) 2011 Michael Niedermayer (michaelni@gmx.at)
     * Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
     *
     * This file is part of Libav.
     *
     * Libav is free software; you can redistribute it and/or
     * modify it under the terms of the GNU Lesser General Public
     * License as published by the Free Software Foundation; either
     * version 2.1 of the License, or (at your option) any later version.
     *
     * Libav is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     * Lesser General Public License for more details.
     *
     * You should have received a copy of the GNU Lesser General Public
     * License along with Libav; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
     */
    
    #include <stdint.h>
    
    
    #include "libavutil/common.h"
    
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    #include "libavutil/libm.h"
    #include "libavutil/samplefmt.h"
    #include "avresample.h"
    #include "internal.h"
    #include "audio_data.h"
    #include "audio_mix.h"
    
    /* channel positions */
    #define FRONT_LEFT              0
    #define FRONT_RIGHT             1
    #define FRONT_CENTER            2
    #define LOW_FREQUENCY           3
    #define BACK_LEFT               4
    #define BACK_RIGHT              5
    #define FRONT_LEFT_OF_CENTER    6
    #define FRONT_RIGHT_OF_CENTER   7
    #define BACK_CENTER             8
    #define SIDE_LEFT               9
    #define SIDE_RIGHT             10
    #define TOP_CENTER             11
    #define TOP_FRONT_LEFT         12
    #define TOP_FRONT_CENTER       13
    #define TOP_FRONT_RIGHT        14
    #define TOP_BACK_LEFT          15
    #define TOP_BACK_CENTER        16
    #define TOP_BACK_RIGHT         17
    #define STEREO_LEFT            29
    #define STEREO_RIGHT           30
    #define WIDE_LEFT              31
    #define WIDE_RIGHT             32
    #define SURROUND_DIRECT_LEFT   33
    #define SURROUND_DIRECT_RIGHT  34
    
    #define LOW_FREQUENCY_2        35
    
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    #define SQRT3_2      1.22474487139158904909  /* sqrt(3/2) */
    
    
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    static av_always_inline int even(uint64_t layout)
    {
        return (!layout || (layout & (layout - 1)));
    }
    
    static int sane_layout(uint64_t layout)
    {
        /* check that there is at least 1 front speaker */
        if (!(layout & AV_CH_LAYOUT_SURROUND))
            return 0;
    
        /* check for left/right symmetry */
        if (!even(layout & (AV_CH_FRONT_LEFT           | AV_CH_FRONT_RIGHT))           ||
            !even(layout & (AV_CH_SIDE_LEFT            | AV_CH_SIDE_RIGHT))            ||
            !even(layout & (AV_CH_BACK_LEFT            | AV_CH_BACK_RIGHT))            ||
            !even(layout & (AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_RIGHT_OF_CENTER)) ||
            !even(layout & (AV_CH_TOP_FRONT_LEFT       | AV_CH_TOP_FRONT_RIGHT))       ||
            !even(layout & (AV_CH_TOP_BACK_LEFT        | AV_CH_TOP_BACK_RIGHT))        ||
            !even(layout & (AV_CH_STEREO_LEFT          | AV_CH_STEREO_RIGHT))          ||
            !even(layout & (AV_CH_WIDE_LEFT            | AV_CH_WIDE_RIGHT))            ||
            !even(layout & (AV_CH_SURROUND_DIRECT_LEFT | AV_CH_SURROUND_DIRECT_RIGHT)))
            return 0;
    
        return 1;
    }
    
    int avresample_build_matrix(uint64_t in_layout, uint64_t out_layout,
                                double center_mix_level, double surround_mix_level,
                                double lfe_mix_level, int normalize,
    
                                double *matrix_out, int stride,
                                enum AVMatrixEncoding matrix_encoding)
    
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    {
        int i, j, out_i, out_j;
        double matrix[64][64] = {{0}};
    
        int64_t unaccounted;
    
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        double maxcoef = 0;
        int in_channels, out_channels;
    
    
        if ((out_layout & AV_CH_LAYOUT_STEREO_DOWNMIX) == AV_CH_LAYOUT_STEREO_DOWNMIX) {
            out_layout = AV_CH_LAYOUT_STEREO;
        }
    
        unaccounted = in_layout & ~out_layout;
    
    
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        in_channels  = av_get_channel_layout_nb_channels( in_layout);
        out_channels = av_get_channel_layout_nb_channels(out_layout);
    
        memset(matrix_out, 0, out_channels * stride * sizeof(*matrix_out));
    
        /* check if layouts are supported */
        if (!in_layout || in_channels > AVRESAMPLE_MAX_CHANNELS)
            return AVERROR(EINVAL);
        if (!out_layout || out_channels > AVRESAMPLE_MAX_CHANNELS)
            return AVERROR(EINVAL);
    
        /* check if layouts are unbalanced or abnormal */
        if (!sane_layout(in_layout) || !sane_layout(out_layout))
            return AVERROR_PATCHWELCOME;
    
        /* route matching input/output channels */
        for (i = 0; i < 64; i++) {
            if (in_layout & out_layout & (1ULL << i))
                matrix[i][i] = 1.0;
        }
    
        /* mix front center to front left/right */
        if (unaccounted & AV_CH_FRONT_CENTER) {
            if ((out_layout & AV_CH_LAYOUT_STEREO) == AV_CH_LAYOUT_STEREO) {
    
                if ((in_layout & AV_CH_LAYOUT_STEREO) == AV_CH_LAYOUT_STEREO) {
                    matrix[FRONT_LEFT ][FRONT_CENTER] += center_mix_level;
                    matrix[FRONT_RIGHT][FRONT_CENTER] += center_mix_level;
                } else {
                    matrix[FRONT_LEFT ][FRONT_CENTER] += M_SQRT1_2;
                    matrix[FRONT_RIGHT][FRONT_CENTER] += M_SQRT1_2;
                }
    
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            } else
                return AVERROR_PATCHWELCOME;
        }
        /* mix front left/right to center */
        if (unaccounted & AV_CH_LAYOUT_STEREO) {
            if (out_layout & AV_CH_FRONT_CENTER) {
                matrix[FRONT_CENTER][FRONT_LEFT ] += M_SQRT1_2;
                matrix[FRONT_CENTER][FRONT_RIGHT] += M_SQRT1_2;
                /* mix left/right/center to center */
                if (in_layout & AV_CH_FRONT_CENTER)
                    matrix[FRONT_CENTER][FRONT_CENTER] = center_mix_level * M_SQRT2;
            } else
                return AVERROR_PATCHWELCOME;
        }
        /* mix back center to back, side, or front */
        if (unaccounted & AV_CH_BACK_CENTER) {
            if (out_layout & AV_CH_BACK_LEFT) {
                matrix[BACK_LEFT ][BACK_CENTER] += M_SQRT1_2;
                matrix[BACK_RIGHT][BACK_CENTER] += M_SQRT1_2;
            } else if (out_layout & AV_CH_SIDE_LEFT) {
                matrix[SIDE_LEFT ][BACK_CENTER] += M_SQRT1_2;
                matrix[SIDE_RIGHT][BACK_CENTER] += M_SQRT1_2;
            } else if (out_layout & AV_CH_FRONT_LEFT) {
    
                if (matrix_encoding == AV_MATRIX_ENCODING_DOLBY ||
                    matrix_encoding == AV_MATRIX_ENCODING_DPLII) {
                    if (unaccounted & (AV_CH_BACK_LEFT | AV_CH_SIDE_LEFT)) {
                        matrix[FRONT_LEFT ][BACK_CENTER] -= surround_mix_level * M_SQRT1_2;
                        matrix[FRONT_RIGHT][BACK_CENTER] += surround_mix_level * M_SQRT1_2;
                    } else {
                        matrix[FRONT_LEFT ][BACK_CENTER] -= surround_mix_level;
                        matrix[FRONT_RIGHT][BACK_CENTER] += surround_mix_level;
                    }
                } else {
                    matrix[FRONT_LEFT ][BACK_CENTER] += surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][BACK_CENTER] += surround_mix_level * M_SQRT1_2;
                }
    
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            } else if (out_layout & AV_CH_FRONT_CENTER) {
                matrix[FRONT_CENTER][BACK_CENTER] += surround_mix_level * M_SQRT1_2;
            } else
                return AVERROR_PATCHWELCOME;
        }
        /* mix back left/right to back center, side, or front */
        if (unaccounted & AV_CH_BACK_LEFT) {
            if (out_layout & AV_CH_BACK_CENTER) {
                matrix[BACK_CENTER][BACK_LEFT ] += M_SQRT1_2;
                matrix[BACK_CENTER][BACK_RIGHT] += M_SQRT1_2;
            } else if (out_layout & AV_CH_SIDE_LEFT) {
                /* if side channels do not exist in the input, just copy back
                   channels to side channels, otherwise mix back into side */
                if (in_layout & AV_CH_SIDE_LEFT) {
                    matrix[SIDE_LEFT ][BACK_LEFT ] += M_SQRT1_2;
                    matrix[SIDE_RIGHT][BACK_RIGHT] += M_SQRT1_2;
                } else {
                    matrix[SIDE_LEFT ][BACK_LEFT ] += 1.0;
                    matrix[SIDE_RIGHT][BACK_RIGHT] += 1.0;
                }
            } else if (out_layout & AV_CH_FRONT_LEFT) {
    
                if (matrix_encoding == AV_MATRIX_ENCODING_DOLBY) {
                    matrix[FRONT_LEFT ][BACK_LEFT ] -= surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_LEFT ][BACK_RIGHT] -= surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][BACK_LEFT ] += surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][BACK_RIGHT] += surround_mix_level * M_SQRT1_2;
                } else if (matrix_encoding == AV_MATRIX_ENCODING_DPLII) {
                    matrix[FRONT_LEFT ][BACK_LEFT ] -= surround_mix_level * SQRT3_2;
                    matrix[FRONT_LEFT ][BACK_RIGHT] -= surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][BACK_LEFT ] += surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][BACK_RIGHT] += surround_mix_level * SQRT3_2;
                } else {
                    matrix[FRONT_LEFT ][BACK_LEFT ] += surround_mix_level;
                    matrix[FRONT_RIGHT][BACK_RIGHT] += surround_mix_level;
                }
    
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            } else if (out_layout & AV_CH_FRONT_CENTER) {
                matrix[FRONT_CENTER][BACK_LEFT ] += surround_mix_level * M_SQRT1_2;
                matrix[FRONT_CENTER][BACK_RIGHT] += surround_mix_level * M_SQRT1_2;
            } else
                return AVERROR_PATCHWELCOME;
        }
        /* mix side left/right into back or front */
        if (unaccounted & AV_CH_SIDE_LEFT) {
            if (out_layout & AV_CH_BACK_LEFT) {
                /* if back channels do not exist in the input, just copy side
                   channels to back channels, otherwise mix side into back */
                if (in_layout & AV_CH_BACK_LEFT) {
                    matrix[BACK_LEFT ][SIDE_LEFT ] += M_SQRT1_2;
                    matrix[BACK_RIGHT][SIDE_RIGHT] += M_SQRT1_2;
                } else {
                    matrix[BACK_LEFT ][SIDE_LEFT ] += 1.0;
                    matrix[BACK_RIGHT][SIDE_RIGHT] += 1.0;
                }
            } else if (out_layout & AV_CH_BACK_CENTER) {
                matrix[BACK_CENTER][SIDE_LEFT ] += M_SQRT1_2;
                matrix[BACK_CENTER][SIDE_RIGHT] += M_SQRT1_2;
            } else if (out_layout & AV_CH_FRONT_LEFT) {
    
                if (matrix_encoding == AV_MATRIX_ENCODING_DOLBY) {
                    matrix[FRONT_LEFT ][SIDE_LEFT ] -= surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_LEFT ][SIDE_RIGHT] -= surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][SIDE_LEFT ] += surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][SIDE_RIGHT] += surround_mix_level * M_SQRT1_2;
                } else if (matrix_encoding == AV_MATRIX_ENCODING_DPLII) {
                    matrix[FRONT_LEFT ][SIDE_LEFT ] -= surround_mix_level * SQRT3_2;
                    matrix[FRONT_LEFT ][SIDE_RIGHT] -= surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][SIDE_LEFT ] += surround_mix_level * M_SQRT1_2;
                    matrix[FRONT_RIGHT][SIDE_RIGHT] += surround_mix_level * SQRT3_2;
                } else {
                    matrix[FRONT_LEFT ][SIDE_LEFT ] += surround_mix_level;
                    matrix[FRONT_RIGHT][SIDE_RIGHT] += surround_mix_level;
                }
    
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            } else if (out_layout & AV_CH_FRONT_CENTER) {
                matrix[FRONT_CENTER][SIDE_LEFT ] += surround_mix_level * M_SQRT1_2;
                matrix[FRONT_CENTER][SIDE_RIGHT] += surround_mix_level * M_SQRT1_2;
            } else
                return AVERROR_PATCHWELCOME;
        }
        /* mix left-of-center/right-of-center into front left/right or center */
        if (unaccounted & AV_CH_FRONT_LEFT_OF_CENTER) {
            if (out_layout & AV_CH_FRONT_LEFT) {
                matrix[FRONT_LEFT ][FRONT_LEFT_OF_CENTER ] += 1.0;
                matrix[FRONT_RIGHT][FRONT_RIGHT_OF_CENTER] += 1.0;
            } else if (out_layout & AV_CH_FRONT_CENTER) {
                matrix[FRONT_CENTER][FRONT_LEFT_OF_CENTER ] += M_SQRT1_2;
                matrix[FRONT_CENTER][FRONT_RIGHT_OF_CENTER] += M_SQRT1_2;
            } else
                return AVERROR_PATCHWELCOME;
        }
        /* mix LFE into front left/right or center */
        if (unaccounted & AV_CH_LOW_FREQUENCY) {
            if (out_layout & AV_CH_FRONT_CENTER) {
                matrix[FRONT_CENTER][LOW_FREQUENCY] += lfe_mix_level;
            } else if (out_layout & AV_CH_FRONT_LEFT) {
                matrix[FRONT_LEFT ][LOW_FREQUENCY] += lfe_mix_level * M_SQRT1_2;
                matrix[FRONT_RIGHT][LOW_FREQUENCY] += lfe_mix_level * M_SQRT1_2;
            } else
                return AVERROR_PATCHWELCOME;
        }
    
        /* transfer internal matrix to output matrix and calculate maximum
           per-channel coefficient sum */
        for (out_i = i = 0; out_i < out_channels && i < 64; i++) {
            double sum = 0;
            for (out_j = j = 0; out_j < in_channels && j < 64; j++) {
                matrix_out[out_i * stride + out_j] = matrix[i][j];
                sum += fabs(matrix[i][j]);
                if (in_layout & (1ULL << j))
                    out_j++;
            }
            maxcoef = FFMAX(maxcoef, sum);
            if (out_layout & (1ULL << i))
                out_i++;
        }
    
        /* normalize */
        if (normalize && maxcoef > 1.0) {
            for (i = 0; i < out_channels; i++)
                for (j = 0; j < in_channels; j++)
                    matrix_out[i * stride + j] /= maxcoef;
        }
    
        return 0;
    }