From a3fd81b6ca213d4a9f8ddfa2883fd0e238d64d04 Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
Date: Sun, 24 Oct 2010 01:14:10 -0400
Subject: [PATCH] Implementing Raymond Chen's comb filter idea
So far, only the post-filter is there.
---
libcelt/celt.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/libcelt/celt.c b/libcelt/celt.c
index 33ef5ddb..25082f55 100644
--- a/libcelt/celt.c
+++ b/libcelt/celt.c
@@ -353,6 +353,24 @@ static void deemphasis(celt_sig *in[], celt_word16 *pcm, int N, int _C, const ce
}
}
+static void comb_filter(celt_word32 *y[2], celt_word32 *x[2], int T0, int T1, int N,
+ int C, celt_word16 g0, celt_word16 g1, const celt_word16 *window, int overlap)
+{
+ int c, i;
+ for (c=0;c<C;c++)
+ {
+ for (i=0;i<overlap;i++)
+ {
+ celt_word16 f;
+ f = MULT16_16_Q15(window[i],window[i]);
+ y[c][i] += MULT16_32_Q15(MULT16_16_Q15((Q15ONE-f),g0),x[c][i-T0])
+ + MULT16_32_Q15(MULT16_16_Q15(f,g1),x[c][i-T1]);
+ }
+ for (i=overlap;i<N;i++)
+ y[c][i] += MULT16_32_Q15(g1,x[c][i-T1]);
+ }
+}
+
static const signed char tf_select_table[4][8] = {
{0, -1, 0, -1, 0,-1, 0,-1},
{0, -1, 0, -2, 1, 0, 1 -1},
@@ -1565,6 +1583,8 @@ int celt_decode_with_ec_float(CELTDecoder * restrict st, const unsigned char *da
/* Compute inverse MDCTs */
compute_inv_mdcts(st->mode, shortBlocks, freq, out_syn, overlap_mem, C, LM);
+ comb_filter(out_syn, out_syn, 40, 40, N, C, QCONST16(0.1f,15), QCONST16(0.1f,15), st->mode->window, st->mode->overlap);
+
deemphasis(out_syn, pcm, N, C, st->mode->preemph, st->preemph_memD);
st->loss_count = 0;
RESTORE_STACK;
--
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