From e500315b1dd7654ec550b5fc013232b3567358e0 Mon Sep 17 00:00:00 2001
From: Vladimir Voroshilov <voroshil@gmail.com>
Date: Mon, 30 Jun 2008 18:03:38 +0000
Subject: gain code, gain pitch and pitch delay decoding for ACELP based codecs

Originally committed as revision 14037 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/acelp_pitch_delay.c | 119 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 libavcodec/acelp_pitch_delay.c

(limited to 'libavcodec/acelp_pitch_delay.c')

diff --git a/libavcodec/acelp_pitch_delay.c b/libavcodec/acelp_pitch_delay.c
new file mode 100644
index 0000000000..9b35fcc892
--- /dev/null
+++ b/libavcodec/acelp_pitch_delay.c
@@ -0,0 +1,119 @@
+/*
+ * gain code, gain pitch and pitch delay decoding
+ *
+ * Copyright (c) 2008 Vladimir Voroshilov
+ *
+ * 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 "avcodec.h"
+#include "acelp_pitch_delay.h"
+#include "acelp_math.h"
+
+int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
+{
+    ac_index += 58;
+    if(ac_index > 254)
+        ac_index = 3 * ac_index - 510;
+    return ac_index;
+}
+
+int ff_acelp_decode_4bit_to_2nd_delay3(
+        int ac_index,
+        int pitch_delay_min)
+{
+    if(ac_index < 4)
+        return 3 * (ac_index + pitch_delay_min);
+    else if(ac_index < 12)
+        return 3 * pitch_delay_min + ac_index + 6;
+    else
+        return 3 * (ac_index + pitch_delay_min) - 18;
+}
+
+int ff_acelp_decode_5_6_bit_to_2nd_delay3(
+        int ac_index,
+        int pitch_delay_min)
+{
+        return 3 * pitch_delay_min + ac_index - 2;
+}
+
+int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
+{
+    if(ac_index < 463)
+        return ac_index + 105;
+    else
+        return 6 * (ac_index - 368);
+}
+int ff_acelp_decode_6bit_to_2nd_delay6(
+        int ac_index,
+        int pitch_delay_min)
+{
+    return 6 * pitch_delay_min + ac_index - 3;
+}
+
+void ff_acelp_update_past_gain(
+    int16_t* quant_energy,
+    int gain_corr_factor,
+    int log2_ma_pred_order,
+    int erasure)
+{
+    int i;
+    int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
+
+    for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
+    {
+        avg_gain       += quant_energy[i-1];
+        quant_energy[i] = quant_energy[i-1];
+    }
+
+    if(erasure)
+        quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
+    else
+        quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
+}
+
+int16_t ff_acelp_decode_gain_code(
+    int gain_corr_factor,
+    const int16_t* fc_v,
+    int mr_energy,
+    const int16_t* quant_energy,
+    const int16_t* ma_prediction_coeff,
+    int subframe_size,
+    int ma_pred_order)
+{
+    int i;
+
+    mr_energy <<= 10;
+
+    for(i=0; i<ma_pred_order; i++)
+        mr_energy += quant_energy[i] * ma_prediction_coeff[i];
+
+#ifdef G729_BITEXACT
+    mr_energy += (((-6165LL * ff_log2(sum_of_squares(fc_v, subframe_size, 0, 0))) >> 3) & ~0x3ff);
+
+    mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)
+
+    return bidir_sal(
+               ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
+               (mr_energy >> 15) - 25
+           );
+#else
+    mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
+                sqrt(sum_of_squares(fc_v, subframe_size, 0, 0));
+    return mr_energy >> 12;
+#endif
+}
-- 
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