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/*
* DCA ADPCM engine
* Copyright (C) 2017 Daniil Cherednik
*
* 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 "dcaadpcm.h"
#include "dcaenc.h"
#include "dca_core.h"
#include "mathops.h"
typedef int32_t premultiplied_coeffs[10];
//assume we have DCA_ADPCM_COEFFS values before x
static inline int64_t calc_corr(const int32_t *x, int len, int j, int k)
{
int n;
int64_t s = 0;
for (n = 0; n < len; n++)
s += MUL64(x[n-j], x[n-k]);
return s;
}
static inline int64_t apply_filter(const int16_t a[DCA_ADPCM_COEFFS], const int64_t corr[15], const int32_t aa[10])
{
int64_t err = 0;
int64_t tmp = 0;
err = corr[0];
tmp += MUL64(a[0], corr[1]);
tmp += MUL64(a[1], corr[2]);
tmp += MUL64(a[2], corr[3]);
tmp += MUL64(a[3], corr[4]);
tmp = norm__(tmp, 13);
tmp += tmp;
err -= tmp;
tmp = 0;
tmp += MUL64(corr[5], aa[0]);
tmp += MUL64(corr[6], aa[1]);
tmp += MUL64(corr[7], aa[2]);
tmp += MUL64(corr[8], aa[3]);
tmp += MUL64(corr[9], aa[4]);
tmp += MUL64(corr[10], aa[5]);
tmp += MUL64(corr[11], aa[6]);
tmp += MUL64(corr[12], aa[7]);
tmp += MUL64(corr[13], aa[8]);
tmp += MUL64(corr[14], aa[9]);
tmp = norm__(tmp, 26);
err += tmp;
return llabs(err);
}
static int64_t find_best_filter(const DCAADPCMEncContext *s, const int32_t *in, int len)
{
const premultiplied_coeffs *precalc_data = s->private_data;
int i, j, k = 0;
int vq = -1;
int64_t err;
int64_t min_err = 1ll << 62;
int64_t corr[15];
for (i = 0; i <= DCA_ADPCM_COEFFS; i++)
for (j = i; j <= DCA_ADPCM_COEFFS; j++)
corr[k++] = calc_corr(in+4, len, i, j);
for (i = 0; i < DCA_ADPCM_VQCODEBOOK_SZ; i++) {
err = apply_filter(ff_dca_adpcm_vb[i], corr, *precalc_data);
if (err < min_err) {
min_err = err;
vq = i;
}
precalc_data++;
}
return vq;
}
static inline int64_t calc_prediction_gain(int pred_vq, const int32_t *in, int32_t *out, int len)
{
int i;
int32_t error;
int64_t signal_energy = 0;
int64_t error_energy = 0;
for (i = 0; i < len; i++) {
error = in[DCA_ADPCM_COEFFS + i] - ff_dcaadpcm_predict(pred_vq, in + i);
out[i] = error;
signal_energy += MUL64(in[DCA_ADPCM_COEFFS + i], in[DCA_ADPCM_COEFFS + i]);
error_energy += MUL64(error, error);
}
if (!error_energy)
return -1;
return signal_energy / error_energy;
}
int ff_dcaadpcm_subband_analysis(const DCAADPCMEncContext *s, const int32_t *in, int len, int *diff)
{
int pred_vq, i;
int32_t input_buffer[16 + DCA_ADPCM_COEFFS];
int32_t input_buffer2[16 + DCA_ADPCM_COEFFS];
int32_t max = 0;
int shift_bits;
uint64_t pg = 0;
for (i = 0; i < len + DCA_ADPCM_COEFFS; i++)
max |= FFABS(in[i]);
// normalize input to simplify apply_filter
shift_bits = av_log2(max) - 11;
for (i = 0; i < len + DCA_ADPCM_COEFFS; i++) {
input_buffer[i] = norm__(in[i], 7);
input_buffer2[i] = norm__(in[i], shift_bits);
}
pred_vq = find_best_filter(s, input_buffer2, len);
if (pred_vq < 0)
return -1;
pg = calc_prediction_gain(pred_vq, input_buffer, diff, len);
// Greater than 10db (10*log(10)) prediction gain to use ADPCM.
// TODO: Tune it.
if (pg < 10)
return -1;
for (i = 0; i < len; i++)
diff[i] <<= 7;
return pred_vq;
}
static void precalc(premultiplied_coeffs *data)
{
int i, j, k;
for (i = 0; i < DCA_ADPCM_VQCODEBOOK_SZ; i++) {
int id = 0;
int32_t t = 0;
for (j = 0; j < DCA_ADPCM_COEFFS; j++) {
for (k = j; k < DCA_ADPCM_COEFFS; k++) {
t = (int32_t)ff_dca_adpcm_vb[i][j] * (int32_t)ff_dca_adpcm_vb[i][k];
if (j != k)
t *= 2;
(*data)[id++] = t;
}
}
data++;
}
}
int ff_dcaadpcm_do_real(int pred_vq_index,
softfloat quant, int32_t scale_factor, int32_t step_size,
const int32_t *prev_hist, const int32_t *in, int32_t *next_hist, int32_t *out,
int len, int32_t peak)
{
int i;
int64_t delta;
int32_t dequant_delta;
int32_t work_bufer[16 + DCA_ADPCM_COEFFS];
memcpy(work_bufer, prev_hist, sizeof(int32_t) * DCA_ADPCM_COEFFS);
for (i = 0; i < len; i++) {
work_bufer[DCA_ADPCM_COEFFS + i] = ff_dcaadpcm_predict(pred_vq_index, &work_bufer[i]);
delta = (int64_t)in[i] - ((int64_t)work_bufer[DCA_ADPCM_COEFFS + i] << 7);
out[i] = quantize_value(av_clip64(delta, -peak, peak), quant);
ff_dca_core_dequantize(&dequant_delta, &out[i], step_size, scale_factor, 0, 1);
work_bufer[DCA_ADPCM_COEFFS+i] += dequant_delta;
}
memcpy(next_hist, &work_bufer[len], sizeof(int32_t) * DCA_ADPCM_COEFFS);
return 0;
}
av_cold int ff_dcaadpcm_init(DCAADPCMEncContext *s)
{
if (!s)
return -1;
s->private_data = av_malloc(sizeof(premultiplied_coeffs) * DCA_ADPCM_VQCODEBOOK_SZ);
if (!s->private_data)
return AVERROR(ENOMEM);
precalc(s->private_data);
return 0;
}
av_cold void ff_dcaadpcm_free(DCAADPCMEncContext *s)
{
if (!s)
return;
av_freep(&s->private_data);
}
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