[FFmpeg-soc] G.723.1 Encoder: Formant perceptual weighting filter

[Mohamed Naufal]

---
 libavcodec/g723_1.c |   31 +++++++++++++++++++++++++++++++
 1 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/libavcodec/g723_1.c b/libavcodec/g723_1.c
index 8364624..8a58f47 100755
--- a/libavcodec/g723_1.c
+++ b/libavcodec/g723_1.c
@@ -1400,6 +1400,36 @@ static void lsp_quantize(int16_t *lsp, int16_t
*prev_lsp, uint8_t *lsp_index)
     get_index(2, 6, 4);
 }

+/**
+ * Formant perceptual weighting filter.
+ *
+ * @param flt_coef filter coefficients
+ * @param unq_lpc  unquantized lpc vector
+ */
+static void perceptual_filter(G723_1_Context *p, int16_t *flt_coef,
+                              int16_t *unq_lpc, int16_t *buf)
+{
+    int16_t vector[FRAME_LEN + LPC_ORDER];
+    int i, j, k, l = 0;
+
+    memcpy(buf, p->iir_mem, sizeof(int16_t) * LPC_ORDER);
+    memcpy(vector, p->fir_mem, sizeof(int16_t) * LPC_ORDER);
+    memcpy(vector + LPC_ORDER, buf + LPC_ORDER, sizeof(int16_t) * FRAME_LEN);
+
+    for (i = LPC_ORDER, j = 0; j < SUBFRAMES; i += SUBFRAME_LEN, j++) {
+        for (k = 0; k < LPC_ORDER; k++) {
+            flt_coef[k + 2*l] = (unq_lpc[k + l] * percept_flt_tbl[0][k] +
+                                  (1 << 14)) >> 15;
+            flt_coef[k + 2*l + LPC_ORDER] = (unq_lpc[k + l] *
percept_flt_tbl[1][k] +
+                                  (1 << 14)) >> 15;
+        }
+        iir_filter(flt_coef + 2*l, flt_coef + 2*l + LPC_ORDER, vector
+ i, buf + i, 0);
+        l += LPC_ORDER;
+    }
+    memcpy(p->iir_mem, buf + FRAME_LEN, sizeof(int16_t) * LPC_ORDER);
+    memcpy(p->fir_mem, vector + FRAME_LEN, sizeof(int16_t) * LPC_ORDER);
+}
+
 static int g723_1_encode_frame(AVCodecContext *avctx, unsigned char *buf,
                                int buf_size, void *data)
 {
@@ -1421,6 +1451,7 @@ static int g723_1_encode_frame(AVCodecContext
*avctx, unsigned char *buf,
            sizeof(int16_t) * HALF_FRAME_LEN);
     memcpy(in, vector + LPC_ORDER, sizeof(int16_t) * FRAME_LEN);

+    perceptual_filter(p, weighted_lpc, unq_lpc, vector);
     return 0;
 }

diff --git a/libavcodec/g723_1_data.h b/libavcodec/g723_1_data.h
index 16d4902..1e23bcb 100644
--- a/libavcodec/g723_1_data.h
+++ b/libavcodec/g723_1_data.h
@@ -1285,3 +1285,13 @@ static const int16_t binomial_window[LPC_ORDER] = {
 static const int16_t bandwidth_expand[LPC_ORDER] = {
     32571, 32376, 32182, 31989, 31797, 31606, 31416, 31228, 31040, 30854
 };
+
+/**
+ * 0.5^i scaled by 2^15
+ */
+static const int16_t percept_flt_tbl[2][LPC_ORDER] = {
+    /* Zero part */
+    {29491, 26542, 23888, 21499, 19349, 17414, 15673, 14106, 12695, 11425},
+    /* Pole part */
+    {16384,  8192,  4096,  2048,  1024,   512,   256,   128,    64,    32}
+};