From 0e1baedec302e6d952bc46708753aaa586b33651 Mon Sep 17 00:00:00 2001
From: Benjamin Larsson <banan@ludd.ltu.se>
Date: Tue, 8 Sep 2009 19:25:54 +0000
Subject: Split out common routines needed in the atrac1 decoder from atrac3.c
 to atrac.c.

Originally committed as revision 19796 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/atrac.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 libavcodec/atrac.c

(limited to 'libavcodec/atrac.c')

diff --git a/libavcodec/atrac.c b/libavcodec/atrac.c
new file mode 100644
index 0000000000..57fde6de78
--- /dev/null
+++ b/libavcodec/atrac.c
@@ -0,0 +1,119 @@
+/*
+ * Atrac common functions
+ * Copyright (c) 2006-2008 Maxim Poliakovski
+ * Copyright (c) 2006-2008 Benjamin Larsson
+ *
+ * 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
+ */
+
+/**
+ * @file libavcodec/atrac.c
+ */
+
+#include <math.h>
+#include <stddef.h>
+#include <stdio.h>
+
+#include "avcodec.h"
+#include "dsputil.h"
+
+float sf_table[64];
+float qmf_window[48];
+
+static const float qmf_48tap_half[24] = {
+   -0.00001461907, -0.00009205479,-0.000056157569,0.00030117269,
+    0.0002422519,  -0.00085293897,-0.0005205574,  0.0020340169,
+    0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,
+   -0.000061169922,-0.01344162,    0.0024626821,  0.021736089,
+   -0.007801671,   -0.034090221,   0.01880949,    0.054326009,
+   -0.043596379,   -0.099384367,   0.13207909,    0.46424159
+};
+
+/**
+ * Generate common tables
+ */
+
+void atrac_generate_tables(void)
+{
+    int i;
+    float s;
+
+    /* Generate scale factors */
+    if (!sf_table[63])
+        for (i=0 ; i<64 ; i++)
+            sf_table[i] = pow(2.0, (i - 15) / 3.0);
+
+    /* Generate the QMF window. */
+    if (!qmf_window[47])
+        for (i=0 ; i<24; i++) {
+            s = qmf_48tap_half[i] * 2.0;
+            qmf_window[i] = qmf_window[47 - i] = s;
+        }
+}
+
+
+/**
+ * Quadrature mirror synthesis filter.
+ *
+ * @param inlo      lower part of spectrum
+ * @param inhi      higher part of spectrum
+ * @param nIn       size of spectrum buffer
+ * @param pOut      out buffer
+ * @param delayBuf  delayBuf buffer
+ * @param temp      temp buffer
+ */
+
+
+void atrac_iqmf (float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)
+{
+    int   i, j;
+    float   *p1, *p3;
+
+    memcpy(temp, delayBuf, 46*sizeof(float));
+
+    p3 = temp + 46;
+
+    /* loop1 */
+    for(i=0; i<nIn; i+=2){
+        p3[2*i+0] = inlo[i  ] + inhi[i  ];
+        p3[2*i+1] = inlo[i  ] - inhi[i  ];
+        p3[2*i+2] = inlo[i+1] + inhi[i+1];
+        p3[2*i+3] = inlo[i+1] - inhi[i+1];
+    }
+
+    /* loop2 */
+    p1 = temp;
+    for (j = nIn; j != 0; j--) {
+        float s1 = 0.0;
+        float s2 = 0.0;
+
+        for (i = 0; i < 48; i += 2) {
+            s1 += p1[i] * qmf_window[i];
+            s2 += p1[i+1] * qmf_window[i+1];
+        }
+
+        pOut[0] = s2;
+        pOut[1] = s1;
+
+        p1 += 2;
+        pOut += 2;
+    }
+
+    /* Update the delay buffer. */
+    memcpy(delayBuf, temp + nIn*2, 46*sizeof(float));
+}
+
-- 
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