From 2146e649c84ff7a96ac17d5e07d7828ee5d0a118 Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <Jean-Marc.Valin@csiro.au>
Date: Mon, 21 Apr 2008 15:08:57 +1000
Subject: [PATCH] Disabling pitch when gain is very small.

---
 libcelt/celt.c        |  2 +-
 libcelt/quant_pitch.c | 12 +++++++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/libcelt/celt.c b/libcelt/celt.c
index d683667f..cb68520a 100644
--- a/libcelt/celt.c
+++ b/libcelt/celt.c
@@ -346,7 +346,7 @@ int EXPORT celt_encode(CELTEncoder * restrict st, celt_int16_t * restrict pcm, u
       /* No pitch, so we just pretend we found a gain of zero */
       for (i=0;i<st->mode->nbPBands;i++)
          gains[i] = 0;
-      ec_enc_uint(&st->enc, 0, 128);
+      ec_enc_bits(&st->enc, 0, 7);
       for (i=0;i<C*N;i++)
          P[i] = 0;
    }
diff --git a/libcelt/quant_pitch.c b/libcelt/quant_pitch.c
index 8363abb1..1053a4e7 100644
--- a/libcelt/quant_pitch.c
+++ b/libcelt/quant_pitch.c
@@ -95,11 +95,21 @@ static void id2gains(int id, celt_pgain_t *gains, int len)
 int quant_pitch(celt_pgain_t *gains, int len, ec_enc *enc)
 {
    int i, id;
+   celt_word32_t gain_sum = 0;
    /*for (i=0;i<len;i++) printf ("%f ", gains[i]);printf ("\n");*/
    /* Convert to a representation where the MSE criterion should be near-optimal */
    for (i=0;i<len;i++)
+   {
       gains[i] = SHR16(Q15ONE-celt_sqrt(Q1515ONE-MULT16_16(gains[i],gains[i])),1);
-   id = vq_index(gains, pgain_table, len, 128);
+      gain_sum = ADD32(gain_sum, EXTEND32(gains[i]));
+   }
+   /* Is it worth encoding the pitch? */
+   if (gain_sum > QCONST32(.3f,15))
+   {
+      id = vq_index(gains, pgain_table, len, 128);
+   } else {
+      id = 0;
+   }
    ec_enc_bits(enc, id, 7);
    /*for (i=0;i<len;i++) printf ("%f ", pgain_table[id*len+i]);printf ("\n");*/
    id2gains(id, gains, len);