avcodec/dcaenc: Initial implementation of ADPCM encoding for DCA encoder

1 files changed, 228 insertions, 0 deletions

diff --git a/libavcodec/dcaadpcm.c b/libavcodec/dcaadpcm.c
new file mode 100644
index 0000000..8742c7c
--- /dev/null
+++ b/libavcodec/dcaadpcm.c
@@ -0,0 +1,228 @@
+/*
+ * 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;
+    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);
+    precalc(s->private_data);
+    return 0;
+}
+
+av_cold void ff_dcaadpcm_free(DCAADPCMEncContext *s)
+{
+    if (!s)
+        return;
+
+    av_freep(&s->private_data);
+}