/*
  * Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
  *

  * This file is part of FFmpeg.

  *

  * FFmpeg 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.
  *

  * FFmpeg 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 FFmpeg; 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"

 #include "libavutil/libm.h"
 #include "libavutil/samplefmt.h"
 #include "avresample.h"
 #include "internal.h"
 #include "audio_data.h"
 #include "audio_mix.h"
 

 static const char * const coeff_type_names[] = { "q8", "q15", "flt" };

 struct AudioMix {
     AVAudioResampleContext *avr;
     enum AVSampleFormat fmt;
     enum AVMixCoeffType coeff_type;
     uint64_t in_layout;
     uint64_t out_layout;
     int in_channels;
     int out_channels;
 
     int ptr_align;
     int samples_align;
     int has_optimized_func;
     const char *func_descr;
     const char *func_descr_generic;
     mix_func *mix;
     mix_func *mix_generic;
 

     int in_matrix_channels;
     int out_matrix_channels;
     int output_zero[AVRESAMPLE_MAX_CHANNELS];
     int input_skip[AVRESAMPLE_MAX_CHANNELS];
     int output_skip[AVRESAMPLE_MAX_CHANNELS];

     int16_t *matrix_q8[AVRESAMPLE_MAX_CHANNELS];
     int32_t *matrix_q15[AVRESAMPLE_MAX_CHANNELS];
     float   *matrix_flt[AVRESAMPLE_MAX_CHANNELS];
     void   **matrix;
 };
 

 void ff_audio_mix_set_func(AudioMix *am, enum AVSampleFormat fmt,
                            enum AVMixCoeffType coeff_type, int in_channels,
                            int out_channels, int ptr_align, int samples_align,
                            const char *descr, void *mix_func)
 {
     if (fmt == am->fmt && coeff_type == am->coeff_type &&

         ( in_channels ==  am->in_matrix_channels ||  in_channels == 0) &&
         (out_channels == am->out_matrix_channels || out_channels == 0)) {

         char chan_str[16];
         am->mix           = mix_func;
         am->func_descr    = descr;
         am->ptr_align     = ptr_align;
         am->samples_align = samples_align;
         if (ptr_align == 1 && samples_align == 1) {
             am->mix_generic        = mix_func;
             am->func_descr_generic = descr;
         } else {
             am->has_optimized_func = 1;
         }
         if (in_channels) {
             if (out_channels)
                 snprintf(chan_str, sizeof(chan_str), "[%d to %d] ",
                          in_channels, out_channels);
             else
                 snprintf(chan_str, sizeof(chan_str), "[%d to any] ",
                          in_channels);
         } else if (out_channels) {
                 snprintf(chan_str, sizeof(chan_str), "[any to %d] ",
                          out_channels);

         } else {
             snprintf(chan_str, sizeof(chan_str), "[any to any] ");

         }
         av_log(am->avr, AV_LOG_DEBUG, "audio_mix: found function: [fmt=%s] "
                "[c=%s] %s(%s)\n", av_get_sample_fmt_name(fmt),

                coeff_type_names[coeff_type], chan_str, descr);

     }
 }
 
 #define MIX_FUNC_NAME(fmt, cfmt) mix_any_ ## fmt ##_## cfmt ##_c
 
 #define MIX_FUNC_GENERIC(fmt, cfmt, stype, ctype, sumtype, expr)            \
 static void MIX_FUNC_NAME(fmt, cfmt)(stype **samples, ctype **matrix,       \
                                      int len, int out_ch, int in_ch)        \
 {                                                                           \
     int i, in, out;                                                         \
     stype temp[AVRESAMPLE_MAX_CHANNELS];                                    \
     for (i = 0; i < len; i++) {                                             \
         for (out = 0; out < out_ch; out++) {                                \
             sumtype sum = 0;                                                \
             for (in = 0; in < in_ch; in++)                                  \
                 sum += samples[in][i] * matrix[out][in];                    \
             temp[out] = expr;                                               \
         }                                                                   \
         for (out = 0; out < out_ch; out++)                                  \
             samples[out][i] = temp[out];                                    \
     }                                                                       \
 }
 
 MIX_FUNC_GENERIC(FLTP, FLT, float,   float,   float,   sum)
 MIX_FUNC_GENERIC(S16P, FLT, int16_t, float,   float,   av_clip_int16(lrintf(sum)))
 MIX_FUNC_GENERIC(S16P, Q15, int16_t, int32_t, int64_t, av_clip_int16(sum >> 15))

 MIX_FUNC_GENERIC(S16P, Q8,  int16_t, int16_t, int32_t, av_clip_int16(sum >>  8))

 
 /* TODO: templatize the channel-specific C functions */
 
 static void mix_2_to_1_fltp_flt_c(float **samples, float **matrix, int len,
                                   int out_ch, int in_ch)
 {
     float *src0 = samples[0];
     float *src1 = samples[1];
     float *dst  = src0;
     float m0    = matrix[0][0];
     float m1    = matrix[0][1];
 
     while (len > 4) {
         *dst++ = *src0++ * m0 + *src1++ * m1;
         *dst++ = *src0++ * m0 + *src1++ * m1;
         *dst++ = *src0++ * m0 + *src1++ * m1;
         *dst++ = *src0++ * m0 + *src1++ * m1;
         len -= 4;
     }
     while (len > 0) {
         *dst++ = *src0++ * m0 + *src1++ * m1;
         len--;
     }
 }
 

 static void mix_2_to_1_s16p_flt_c(int16_t **samples, float **matrix, int len,
                                   int out_ch, int in_ch)
 {
     int16_t *src0 = samples[0];
     int16_t *src1 = samples[1];
     int16_t *dst  = src0;
     float m0      = matrix[0][0];
     float m1      = matrix[0][1];
 
     while (len > 4) {
         *dst++ = av_clip_int16(lrintf(*src0++ * m0 + *src1++ * m1));
         *dst++ = av_clip_int16(lrintf(*src0++ * m0 + *src1++ * m1));
         *dst++ = av_clip_int16(lrintf(*src0++ * m0 + *src1++ * m1));
         *dst++ = av_clip_int16(lrintf(*src0++ * m0 + *src1++ * m1));
         len -= 4;
     }
     while (len > 0) {
         *dst++ = av_clip_int16(lrintf(*src0++ * m0 + *src1++ * m1));
         len--;
     }
 }
 
 static void mix_2_to_1_s16p_q8_c(int16_t **samples, int16_t **matrix, int len,
                                  int out_ch, int in_ch)
 {
     int16_t *src0 = samples[0];
     int16_t *src1 = samples[1];
     int16_t *dst  = src0;
     int16_t m0    = matrix[0][0];
     int16_t m1    = matrix[0][1];
 
     while (len > 4) {
         *dst++ = (*src0++ * m0 + *src1++ * m1) >> 8;
         *dst++ = (*src0++ * m0 + *src1++ * m1) >> 8;
         *dst++ = (*src0++ * m0 + *src1++ * m1) >> 8;
         *dst++ = (*src0++ * m0 + *src1++ * m1) >> 8;
         len -= 4;
     }
     while (len > 0) {
         *dst++ = (*src0++ * m0 + *src1++ * m1) >> 8;
         len--;
     }
 }
 

 static void mix_1_to_2_fltp_flt_c(float **samples, float **matrix, int len,
                                   int out_ch, int in_ch)
 {
     float v;
     float *dst0 = samples[0];
     float *dst1 = samples[1];
     float *src  = dst0;
     float m0    = matrix[0][0];
     float m1    = matrix[1][0];
 
     while (len > 4) {
         v = *src++;

         *dst0++ = v * m0;
         *dst1++ = v * m1;

         v = *src++;

         *dst0++ = v * m0;
         *dst1++ = v * m1;

         v = *src++;

         *dst0++ = v * m0;
         *dst1++ = v * m1;

         v = *src++;

         *dst0++ = v * m0;
         *dst1++ = v * m1;

         len -= 4;
     }
     while (len > 0) {
         v = *src++;

         *dst0++ = v * m0;
         *dst1++ = v * m1;

         len--;
     }
 }
 
 static void mix_6_to_2_fltp_flt_c(float **samples, float **matrix, int len,
                                   int out_ch, int in_ch)
 {
     float v0, v1;
     float *src0 = samples[0];
     float *src1 = samples[1];
     float *src2 = samples[2];
     float *src3 = samples[3];
     float *src4 = samples[4];
     float *src5 = samples[5];
     float *dst0 = src0;
     float *dst1 = src1;
     float *m0   = matrix[0];
     float *m1   = matrix[1];
 
     while (len > 0) {
         v0 = *src0++;
         v1 = *src1++;
         *dst0++ = v0      * m0[0] +
                   v1      * m0[1] +
                   *src2   * m0[2] +
                   *src3   * m0[3] +
                   *src4   * m0[4] +
                   *src5   * m0[5];
         *dst1++ = v0      * m1[0] +
                   v1      * m1[1] +
                   *src2++ * m1[2] +
                   *src3++ * m1[3] +
                   *src4++ * m1[4] +
                   *src5++ * m1[5];
         len--;
     }
 }
 
 static void mix_2_to_6_fltp_flt_c(float **samples, float **matrix, int len,
                                   int out_ch, int in_ch)
 {
     float v0, v1;
     float *dst0 = samples[0];
     float *dst1 = samples[1];
     float *dst2 = samples[2];
     float *dst3 = samples[3];
     float *dst4 = samples[4];
     float *dst5 = samples[5];
     float *src0 = dst0;
     float *src1 = dst1;
 
     while (len > 0) {
         v0 = *src0++;
         v1 = *src1++;
         *dst0++ = v0 * matrix[0][0] + v1 * matrix[0][1];
         *dst1++ = v0 * matrix[1][0] + v1 * matrix[1][1];
         *dst2++ = v0 * matrix[2][0] + v1 * matrix[2][1];
         *dst3++ = v0 * matrix[3][0] + v1 * matrix[3][1];
         *dst4++ = v0 * matrix[4][0] + v1 * matrix[4][1];
         *dst5++ = v0 * matrix[5][0] + v1 * matrix[5][1];
         len--;
     }
 }
 

 static av_cold int mix_function_init(AudioMix *am)

 {

     am->func_descr = am->func_descr_generic = "n/a";
     am->mix = am->mix_generic = NULL;
 

     /* no need to set a mix function when we're skipping mixing */

     if (!am->in_matrix_channels || !am->out_matrix_channels)

         return 0;
 

     /* any-to-any C versions */
 
     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_FLTP, AV_MIX_COEFF_TYPE_FLT,
                           0, 0, 1, 1, "C", MIX_FUNC_NAME(FLTP, FLT));
 
     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_S16P, AV_MIX_COEFF_TYPE_FLT,
                           0, 0, 1, 1, "C", MIX_FUNC_NAME(S16P, FLT));
 
     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_S16P, AV_MIX_COEFF_TYPE_Q15,
                           0, 0, 1, 1, "C", MIX_FUNC_NAME(S16P, Q15));
 

     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_S16P, AV_MIX_COEFF_TYPE_Q8,
                           0, 0, 1, 1, "C", MIX_FUNC_NAME(S16P, Q8));

 
     /* channel-specific C versions */
 
     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_FLTP, AV_MIX_COEFF_TYPE_FLT,
                           2, 1, 1, 1, "C", mix_2_to_1_fltp_flt_c);
 

     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_S16P, AV_MIX_COEFF_TYPE_FLT,
                           2, 1, 1, 1, "C", mix_2_to_1_s16p_flt_c);
 
     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_S16P, AV_MIX_COEFF_TYPE_Q8,
                           2, 1, 1, 1, "C", mix_2_to_1_s16p_q8_c);
 

     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_FLTP, AV_MIX_COEFF_TYPE_FLT,
                           1, 2, 1, 1, "C", mix_1_to_2_fltp_flt_c);
 
     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_FLTP, AV_MIX_COEFF_TYPE_FLT,
                           6, 2, 1, 1, "C", mix_6_to_2_fltp_flt_c);
 
     ff_audio_mix_set_func(am, AV_SAMPLE_FMT_FLTP, AV_MIX_COEFF_TYPE_FLT,
                           2, 6, 1, 1, "C", mix_2_to_6_fltp_flt_c);
 
     if (ARCH_X86)
         ff_audio_mix_init_x86(am);
 
     if (!am->mix) {
         av_log(am->avr, AV_LOG_ERROR, "audio_mix: NO FUNCTION FOUND: [fmt=%s] "
                "[c=%s] [%d to %d]\n", av_get_sample_fmt_name(am->fmt),
                coeff_type_names[am->coeff_type], am->in_channels,
                am->out_channels);
         return AVERROR_PATCHWELCOME;
     }
     return 0;
 }
 

 AudioMix *ff_audio_mix_alloc(AVAudioResampleContext *avr)

 {

     AudioMix *am;

     int ret;
 

     am = av_mallocz(sizeof(*am));
     if (!am)
         return NULL;
     am->avr = avr;
 

     if (avr->internal_sample_fmt != AV_SAMPLE_FMT_S16P &&
         avr->internal_sample_fmt != AV_SAMPLE_FMT_FLTP) {
         av_log(avr, AV_LOG_ERROR, "Unsupported internal format for "
                "mixing: %s\n",
                av_get_sample_fmt_name(avr->internal_sample_fmt));

         goto error;

     }
 

     am->fmt          = avr->internal_sample_fmt;
     am->coeff_type   = avr->mix_coeff_type;
     am->in_layout    = avr->in_channel_layout;
     am->out_layout   = avr->out_channel_layout;
     am->in_channels  = avr->in_channels;
     am->out_channels = avr->out_channels;
 

     /* build matrix if the user did not already set one */

     if (avr->mix_matrix) {
         ret = ff_audio_mix_set_matrix(am, avr->mix_matrix, avr->in_channels);
         if (ret < 0)
             goto error;
         av_freep(&avr->mix_matrix);

     } else {

         double *matrix_dbl = av_mallocz(avr->out_channels * avr->in_channels *
                                         sizeof(*matrix_dbl));
         if (!matrix_dbl)

             goto error;

 
         ret = avresample_build_matrix(avr->in_channel_layout,
                                       avr->out_channel_layout,
                                       avr->center_mix_level,
                                       avr->surround_mix_level,

                                       avr->lfe_mix_level,
                                       avr->normalize_mix_level,
                                       matrix_dbl,

                                       avr->in_channels,
                                       avr->matrix_encoding);

         if (ret < 0) {
             av_free(matrix_dbl);

             goto error;

         }
 

         ret = ff_audio_mix_set_matrix(am, matrix_dbl, avr->in_channels);
         if (ret < 0) {
             av_log(avr, AV_LOG_ERROR, "error setting mix matrix\n");
             av_free(matrix_dbl);
             goto error;
         }
 

         av_free(matrix_dbl);
     }
 

     return am;
 
 error:
     av_free(am);
     return NULL;

 }
 

 void ff_audio_mix_free(AudioMix **am_p)

 {

     AudioMix *am;
 
     if (!*am_p)

         return;

     am = *am_p;
 

     if (am->matrix) {
         av_free(am->matrix[0]);
         am->matrix = NULL;
     }

     memset(am->matrix_q8,  0, sizeof(am->matrix_q8 ));

     memset(am->matrix_q15, 0, sizeof(am->matrix_q15));
     memset(am->matrix_flt, 0, sizeof(am->matrix_flt));

 
     av_freep(am_p);

 }
 
 int ff_audio_mix(AudioMix *am, AudioData *src)
 {
     int use_generic = 1;
     int len = src->nb_samples;

     int i, j;

 
     /* determine whether to use the optimized function based on pointer and
        samples alignment in both the input and output */
     if (am->has_optimized_func) {
         int aligned_len = FFALIGN(len, am->samples_align);
         if (!(src->ptr_align % am->ptr_align) &&
             src->samples_align >= aligned_len) {
             len = aligned_len;
             use_generic = 0;
         }
     }

     av_log(am->avr, AV_LOG_TRACE, "audio_mix: %d samples - %d to %d channels (%s)\n",

             src->nb_samples, am->in_channels, am->out_channels,
             use_generic ? am->func_descr_generic : am->func_descr);
 

     if (am->in_matrix_channels && am->out_matrix_channels) {
         uint8_t **data;

         uint8_t *data0[AVRESAMPLE_MAX_CHANNELS] = { NULL };

 
         if (am->out_matrix_channels < am->out_channels ||
              am->in_matrix_channels <  am->in_channels) {
             for (i = 0, j = 0; i < FFMAX(am->in_channels, am->out_channels); i++) {
                 if (am->input_skip[i] || am->output_skip[i] || am->output_zero[i])
                     continue;
                 data0[j++] = src->data[i];
             }
             data = data0;
         } else {
             data = src->data;
         }
 
         if (use_generic)
             am->mix_generic(data, am->matrix, len, am->out_matrix_channels,
                             am->in_matrix_channels);
         else
             am->mix(data, am->matrix, len, am->out_matrix_channels,
                     am->in_matrix_channels);
     }
 
     if (am->out_matrix_channels < am->out_channels) {
         for (i = 0; i < am->out_channels; i++)
             if (am->output_zero[i])
                 av_samples_set_silence(&src->data[i], 0, len, 1, am->fmt);
     }

 
     ff_audio_data_set_channels(src, am->out_channels);
 
     return 0;
 }

 
 int ff_audio_mix_get_matrix(AudioMix *am, double *matrix, int stride)
 {

     int i, o, i0, o0;

 
     if ( am->in_channels <= 0 ||  am->in_channels > AVRESAMPLE_MAX_CHANNELS ||
         am->out_channels <= 0 || am->out_channels > AVRESAMPLE_MAX_CHANNELS) {

         av_log(am->avr, AV_LOG_ERROR, "Invalid channel counts\n");

         return AVERROR(EINVAL);
     }
 
 #define GET_MATRIX_CONVERT(suffix, scale)                                   \
     if (!am->matrix_ ## suffix[0]) {                                        \

         av_log(am->avr, AV_LOG_ERROR, "matrix is not set\n");               \

         return AVERROR(EINVAL);                                             \
     }                                                                       \

     for (o = 0, o0 = 0; o < am->out_channels; o++) {                        \
         for (i = 0, i0 = 0; i < am->in_channels; i++) {                     \
             if (am->input_skip[i] || am->output_zero[o])                    \
                 matrix[o * stride + i] = 0.0;                               \
             else                                                            \
                 matrix[o * stride + i] = am->matrix_ ## suffix[o0][i0] *    \
                                          (scale);                           \
             if (!am->input_skip[i])                                         \
                 i0++;                                                       \
         }                                                                   \
         if (!am->output_zero[o])                                            \
             o0++;                                                           \
     }

 
     switch (am->coeff_type) {
     case AV_MIX_COEFF_TYPE_Q8:
         GET_MATRIX_CONVERT(q8, 1.0 / 256.0);
         break;
     case AV_MIX_COEFF_TYPE_Q15:
         GET_MATRIX_CONVERT(q15, 1.0 / 32768.0);
         break;
     case AV_MIX_COEFF_TYPE_FLT:
         GET_MATRIX_CONVERT(flt, 1.0);
         break;
     default:

         av_log(am->avr, AV_LOG_ERROR, "Invalid mix coeff type\n");

         return AVERROR(EINVAL);
     }
 
     return 0;
 }
 

 static void reduce_matrix(AudioMix *am, const double *matrix, int stride)

 {

     int i, o;

     memset(am->output_zero, 0, sizeof(am->output_zero));
     memset(am->input_skip,  0, sizeof(am->input_skip));

     memset(am->output_skip, 0, sizeof(am->output_skip));

 
     /* exclude output channels if they can be zeroed instead of mixed */
     for (o = 0; o < am->out_channels; o++) {
         int zero = 1;
 
         /* check if the output is always silent */
         for (i = 0; i < am->in_channels; i++) {
             if (matrix[o * stride + i] != 0.0) {
                 zero = 0;
                 break;
             }
         }
         /* check if the corresponding input channel makes a contribution to
            any output channel */
         if (o < am->in_channels) {
             for (i = 0; i < am->out_channels; i++) {
                 if (matrix[i * stride + o] != 0.0) {
                     zero = 0;
                     break;
                 }
             }
         }
         if (zero) {
             am->output_zero[o] = 1;
             am->out_matrix_channels--;

             if (o < am->in_channels)
                 am->in_matrix_channels--;

         }
     }

     if (am->out_matrix_channels == 0 || am->in_matrix_channels == 0) {
         am->out_matrix_channels = 0;

         am->in_matrix_channels = 0;

         return;

     }
 
     /* skip input channels that contribute fully only to the corresponding
        output channel */
     for (i = 0; i < FFMIN(am->in_channels, am->out_channels); i++) {
         int skip = 1;
 
         for (o = 0; o < am->out_channels; o++) {

             int i0;

             if ((o != i && matrix[o * stride + i] != 0.0) ||
                 (o == i && matrix[o * stride + i] != 1.0)) {
                 skip = 0;
                 break;
             }

             /* if the input contributes fully to the output, also check that no
                other inputs contribute to this output */
             if (o == i) {
                 for (i0 = 0; i0 < am->in_channels; i0++) {
                     if (i0 != i && matrix[o * stride + i0] != 0.0) {
                         skip = 0;
                         break;
                     }
                 }
             }

         }
         if (skip) {
             am->input_skip[i] = 1;
             am->in_matrix_channels--;
         }
     }
     /* skip input channels that do not contribute to any output channel */
     for (; i < am->in_channels; i++) {
         int contrib = 0;
 
         for (o = 0; o < am->out_channels; o++) {
             if (matrix[o * stride + i] != 0.0) {
                 contrib = 1;
                 break;
             }
         }
         if (!contrib) {
             am->input_skip[i] = 1;
             am->in_matrix_channels--;
         }
     }
     if (am->in_matrix_channels == 0) {
         am->out_matrix_channels = 0;

         return;

     }
 
     /* skip output channels that only get full contribution from the
        corresponding input channel */
     for (o = 0; o < FFMIN(am->in_channels, am->out_channels); o++) {
         int skip = 1;

         int o0;

 
         for (i = 0; i < am->in_channels; i++) {
             if ((o != i && matrix[o * stride + i] != 0.0) ||
                 (o == i && matrix[o * stride + i] != 1.0)) {
                 skip = 0;
                 break;
             }
         }

         /* check if the corresponding input channel makes a contribution to
            any other output channel */
         i = o;
         for (o0 = 0; o0 < am->out_channels; o0++) {
             if (o0 != i && matrix[o0 * stride + i] != 0.0) {
                 skip = 0;
                 break;
             }
         }

         if (skip) {
             am->output_skip[o] = 1;
             am->out_matrix_channels--;
         }
     }
     if (am->out_matrix_channels == 0) {
         am->in_matrix_channels = 0;

         return;

     }

 }
 
 int ff_audio_mix_set_matrix(AudioMix *am, const double *matrix, int stride)
 {
     int i, o, i0, o0, ret;
     char in_layout_name[128];
     char out_layout_name[128];
 
     if ( am->in_channels <= 0 ||  am->in_channels > AVRESAMPLE_MAX_CHANNELS ||
         am->out_channels <= 0 || am->out_channels > AVRESAMPLE_MAX_CHANNELS) {
         av_log(am->avr, AV_LOG_ERROR, "Invalid channel counts\n");
         return AVERROR(EINVAL);
     }
 
     if (am->matrix) {
         av_free(am->matrix[0]);
         am->matrix = NULL;
     }
 
     am->in_matrix_channels  = am->in_channels;
     am->out_matrix_channels = am->out_channels;
 
     reduce_matrix(am, matrix, stride);

 #define CONVERT_MATRIX(type, expr)                                          \

     am->matrix_## type[0] = av_mallocz(am->out_matrix_channels *            \
                                        am->in_matrix_channels  *            \

                                        sizeof(*am->matrix_## type[0]));     \
     if (!am->matrix_## type[0])                                             \
         return AVERROR(ENOMEM);                                             \

     for (o = 0, o0 = 0; o < am->out_channels; o++) {                        \
         if (am->output_zero[o] || am->output_skip[o])                       \
             continue;                                                       \
         if (o0 > 0)                                                         \
             am->matrix_## type[o0] = am->matrix_## type[o0 - 1] +           \
                                      am->in_matrix_channels;                \
         for (i = 0, i0 = 0; i < am->in_channels; i++) {                     \
             double v;                                                       \

             if (am->input_skip[i] || am->output_zero[i])                    \

                 continue;                                                   \
             v = matrix[o * stride + i];                                     \
             am->matrix_## type[o0][i0] = expr;                              \
             i0++;                                                           \

         }                                                                   \

         o0++;                                                               \

     }                                                                       \
     am->matrix = (void **)am->matrix_## type;
 

     if (am->in_matrix_channels && am->out_matrix_channels) {

         switch (am->coeff_type) {
         case AV_MIX_COEFF_TYPE_Q8:
             CONVERT_MATRIX(q8, av_clip_int16(lrint(256.0 * v)))
             break;
         case AV_MIX_COEFF_TYPE_Q15:
             CONVERT_MATRIX(q15, av_clipl_int32(llrint(32768.0 * v)))
             break;
         case AV_MIX_COEFF_TYPE_FLT:
             CONVERT_MATRIX(flt, v)
             break;
         default:
             av_log(am->avr, AV_LOG_ERROR, "Invalid mix coeff type\n");
             return AVERROR(EINVAL);
         }

     }

     ret = mix_function_init(am);
     if (ret < 0)
         return ret;
 
     av_get_channel_layout_string(in_layout_name, sizeof(in_layout_name),
                                  am->in_channels, am->in_layout);
     av_get_channel_layout_string(out_layout_name, sizeof(out_layout_name),
                                  am->out_channels, am->out_layout);
     av_log(am->avr, AV_LOG_DEBUG, "audio_mix: %s to %s\n",
            in_layout_name, out_layout_name);
     av_log(am->avr, AV_LOG_DEBUG, "matrix size: %d x %d\n",
            am->in_matrix_channels, am->out_matrix_channels);
     for (o = 0; o < am->out_channels; o++) {
         for (i = 0; i < am->in_channels; i++) {
             if (am->output_zero[o])
                 av_log(am->avr, AV_LOG_DEBUG, "  (ZERO)");

             else if (am->input_skip[i] || am->output_zero[i] || am->output_skip[o])

                 av_log(am->avr, AV_LOG_DEBUG, "  (SKIP)");
             else
                 av_log(am->avr, AV_LOG_DEBUG, "  %0.3f ",
                        matrix[o * am->in_channels + i]);
         }
         av_log(am->avr, AV_LOG_DEBUG, "\n");
     }
 
     return 0;

 }