[FFmpeg-soc] G.723.1 Encoder: Compute fixed CB excitation
Mohamed Naufal
naufal11 at gmail.com
Fri Aug 20 09:13:20 CEST 2010
---
libavcodec/g723_1.c | 224 ++++++++++++++++++++++++++++++++++++++++++++++
libavcodec/g723_1_data.h | 12 +++
2 files changed, 236 insertions(+), 0 deletions(-)
diff --git a/libavcodec/g723_1.c b/libavcodec/g723_1.c
index fa57527..d344217 100755
--- a/libavcodec/g723_1.c
+++ b/libavcodec/g723_1.c
@@ -1793,6 +1793,228 @@ static void sub_acb_contrib(int16_t *residual,
int16_t *impulse_resp,
}
}
+/**
+ * Quantize the residual signal using the fixed codebook (MP-MLQ).
+ *
+ * @param optim optimized fixed codebook parameters
+ * @param buf excitation vector
+ */
+static void get_fcb_param(FCBParam *optim, int16_t *impulse_resp,
+ int16_t *buf, int pulse_cnt, int pitch_lag)
+{
+ FCBParam param;
+ int16_t impulse_r[SUBFRAME_LEN];
+ int16_t temp_corr[SUBFRAME_LEN];
+ int16_t impulse_corr[SUBFRAME_LEN];
+
+ int ccr1[SUBFRAME_LEN];
+ int ccr2[SUBFRAME_LEN];
+ int amp, err, max, max_amp_index, min, scale, i, j, k, l;
+
+ int64_t temp;
+
+ /* Update impulse response */
+ memcpy(impulse_r, impulse_resp, sizeof(int16_t) * SUBFRAME_LEN);
+ param.dirac_train = 0;
+ if (pitch_lag < SUBFRAME_LEN - 2) {
+ param.dirac_train = 1;
+ gen_dirac_train(impulse_r, pitch_lag);
+ }
+
+ for (i = 0; i < SUBFRAME_LEN; i++)
+ temp_corr[i] = impulse_r[i] >> 1;
+
+ /* Compute impulse response autocorrelation */
+ temp = dot_product(temp_corr, temp_corr, SUBFRAME_LEN, 1);
+
+ scale = normalize_bits_int32(temp);
+ impulse_corr[0] = av_clipl_int32((temp << scale) + (1 << 15)) >> 16;
+
+ for (i = 1; i < SUBFRAME_LEN; i++) {
+ temp = dot_product(temp_corr + i, temp_corr, SUBFRAME_LEN - i, 1);
+ impulse_corr[i] = av_clipl_int32((temp << scale) + (1 << 15)) >> 16;
+ }
+
+ /* Compute crosscorrelation of impulse response with residual signal */
+ scale -= 4;
+ for (i = 0; i < SUBFRAME_LEN; i++){
+ temp = dot_product(buf + i, impulse_r, SUBFRAME_LEN - i, 1);
+ if (scale < 0)
+ ccr1[i] = temp >> -scale;
+ else
+ ccr1[i] = av_clipl_int32(temp << scale);
+ }
+
+ /* Search loop */
+ for (i = 0; i < GRID_SIZE; i++) {
+ /* Maximize the crosscorrelation */
+ max = 0;
+ for (j = i; j < SUBFRAME_LEN; j += GRID_SIZE) {
+ temp = FFABS(ccr1[j]);
+ if (temp >= max) {
+ max = temp;
+ param.pulse_pos[0] = j;
+ }
+ }
+
+ /* Quantize the gain (max crosscorrelation/impulse_corr[0]) */
+ amp = max;
+ min = 1 << 30;
+ max_amp_index = GAIN_LEVELS - 2;
+ for (j = max_amp_index; j >= 2; j--) {
+ temp = av_clipl_int32((int64_t)fixed_cb_gain[j] *
+ impulse_corr[0] << 1);
+ temp = FFABS(temp - amp);
+ if (temp < min) {
+ min = temp;
+ max_amp_index = j;
+ }
+ }
+
+ max_amp_index--;
+ /* Select additional gain values */
+ for (j = 1; j < 5; j++) {
+ for (k = i; k < SUBFRAME_LEN; k += GRID_SIZE) {
+ temp_corr[k] = 0;
+ ccr2[k] = ccr1[k];
+ }
+ param.amp_index = max_amp_index + j - 2;
+ amp = fixed_cb_gain[param.amp_index];
+
+ param.pulse_sign[0] = (ccr2[param.pulse_pos[0]] < 0) ? -amp : amp;
+
+ temp_corr[param.pulse_pos[0]] = 1;
+
+ for (k = 1; k < pulse_cnt; k++) {
+ max = -1 << 30;
+ for (l = i; l < SUBFRAME_LEN; l += GRID_SIZE) {
+ if (temp_corr[l])
+ continue;
+ temp = impulse_corr[FFABS(l - param.pulse_pos[k - 1])];
+ temp = av_clipl_int32((int64_t)temp *
+ param.pulse_sign[k - 1] << 1);
+ ccr2[l] -= temp;
+ temp = FFABS(ccr2[l]);
+
+ if (temp > max) {
+ max = temp;
+ param.pulse_pos[k] = l;
+ }
+ }
+
+ param.pulse_sign[k] = (ccr2[param.pulse_pos[k]] < 0) ?
+ -amp : amp;
+ temp_corr[param.pulse_pos[k]] = 1;
+ }
+
+ /* Create the error vector */
+ memset(temp_corr, 0, sizeof(int16_t) * SUBFRAME_LEN);
+
+ for (k = 0; k < pulse_cnt; k++)
+ temp_corr[param.pulse_pos[k]] = param.pulse_sign[k];
+
+ for (k = SUBFRAME_LEN - 1; k >= 0; k--) {
+ temp = 0;
+ for (l = 0; l <= k; l++) {
+ int prod = av_clipl_int32((int64_t)temp_corr[l] *
+ impulse_r[k - l] << 1);
+ temp = av_clipl_int32(temp + prod);
+ }
+ temp_corr[k] = temp << 2 >> 16;
+ }
+
+ /* Compute square of error */
+ err = 0;
+ for (k = 0; k < SUBFRAME_LEN; k++) {
+ int64_t prod;
+ prod = av_clipl_int32((int64_t)buf[k] * temp_corr[k] << 1);
+ err = av_clipl_int32(err - prod);
+ prod = av_clipl_int32((int64_t)temp_corr[k] * temp_corr[k]);
+ err = av_clipl_int32(err + prod);
+ }
+
+ /* Minimize */
+ if (err < optim->min_err) {
+ optim->min_err = err;
+ optim->grid_index = i;
+ optim->amp_index = param.amp_index;
+ optim->dirac_train = param.dirac_train;
+
+ for (k = 0; k < pulse_cnt; k++) {
+ optim->pulse_sign[k] = param.pulse_sign[k];
+ optim->pulse_pos[k] = param.pulse_pos[k];
+ }
+ }
+ }
+ }
+}
+
+/**
+ * Combinatorially encode the pulse position and gain of the
+ * current subframe.
+ *
+ * @param optim optimized fixed codebook parameters
+ * @param buf excitation vector
+ */
+static void pack_fcb_param(G723_1_Subframe *subfrm, FCBParam *optim,
+ int16_t *buf, int pulse_cnt)
+{
+ int i, j;
+
+ j = PULSE_MAX - pulse_cnt;
+
+ subfrm->pulse_sign = 0;
+ subfrm->pulse_pos = 0;
+
+ for (i = 0; i < SUBFRAME_LEN >> 1; i++) {
+ int val = buf[optim->grid_index + (i << 1)];
+ if (!val) {
+ subfrm->pulse_pos += combinatorial_table[j][i];
+ } else {
+ subfrm->pulse_sign <<= 1;
+ if (val < 0) subfrm->pulse_sign++;
+ j++;
+
+ if (j == PULSE_MAX) break;
+ }
+ }
+ subfrm->amp_index = optim->amp_index;
+ subfrm->grid_index = optim->grid_index;
+ subfrm->dirac_train = optim->dirac_train;
+}
+
+/**
+ * Compute the fixed codebook excitation.
+ *
+ * @param buf target vector
+ * @param impulse_resp impulse response of the combined filter
+ */
+static void fcb_search(G723_1_Context *p, int16_t *impulse_resp,
+ int16_t *buf, int index)
+{
+ FCBParam optim;
+ int pulse_cnt = pulses[index];
+ int i;
+
+ optim.min_err = 1 << 30;
+ get_fcb_param(&optim, impulse_resp, buf, pulse_cnt, SUBFRAME_LEN);
+
+ if (p->pitch_lag[index >> 1] < SUBFRAME_LEN - 2) {
+ get_fcb_param(&optim, impulse_resp, buf, pulse_cnt,
+ p->pitch_lag[index >> 1]);
+ }
+
+ /* Reconstruct the excitation */
+ memset(buf, 0, sizeof(int16_t) * SUBFRAME_LEN);
+ for (i = 0; i < pulse_cnt; i++)
+ buf[optim.pulse_pos[i]] = optim.pulse_sign[i];
+
+ pack_fcb_param(&p->subframe[index], &optim, buf, pulse_cnt);
+
+ if (optim.dirac_train)
+ gen_dirac_train(buf, p->pitch_lag[index >> 1]);
+}
+
static int g723_1_encode_frame(AVCodecContext *avctx, unsigned char *buf,
int buf_size, void *data)
{
@@ -1881,6 +2103,8 @@ static int g723_1_encode_frame(AVCodecContext
*avctx, unsigned char *buf,
p->subframe[i], p->cur_rate);
sub_acb_contrib(residual, impulse_resp, in);
+ fcb_search(p, impulse_resp, in, i);
+
offset += LPC_ORDER;
in += SUBFRAME_LEN;
}
diff --git a/libavcodec/g723_1_data.h b/libavcodec/g723_1_data.h
index ea1a86d..199185d 100644
--- a/libavcodec/g723_1_data.h
+++ b/libavcodec/g723_1_data.h
@@ -90,6 +90,18 @@ typedef struct {
} HFParam;
/**
+ * Optimized fixed codebook excitation parameters
+ */
+typedef struct {
+ int min_err;
+ int amp_index;
+ int grid_index;
+ int dirac_train;
+ int pulse_pos[PULSE_MAX];
+ int pulse_sign[PULSE_MAX];
+} FCBParam;
+
+/**
* Postfilter gain weighting factors scaled by 2^15
*/
static const int16_t ppf_gain_weight[2] = {0x1800, 0x2000};
--
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