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Diffstat (limited to 'libavcodec/mpegaudio_tablegen.h')
-rw-r--r--libavcodec/mpegaudio_tablegen.h13
1 files changed, 7 insertions, 6 deletions
diff --git a/libavcodec/mpegaudio_tablegen.h b/libavcodec/mpegaudio_tablegen.h
index a222f2c423..6c15d3cb03 100644
--- a/libavcodec/mpegaudio_tablegen.h
+++ b/libavcodec/mpegaudio_tablegen.h
@@ -3,20 +3,20 @@
*
* Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
*
- * This file is part of Libav.
+ * This file is part of FFmpeg.
*
- * Libav is free software; you can redistribute it and/or
+ * 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.
*
- * Libav is distributed in the hope that it will be useful,
+ * 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 Libav; if not, write to the Free Software
+ * License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
@@ -39,6 +39,7 @@ static float exp_table_float[512];
static float expval_table_float[512][16];
#define FRAC_BITS 23
+#define IMDCT_SCALAR 1.759
static void mpegaudio_tableinit(void)
{
@@ -47,7 +48,7 @@ static void mpegaudio_tableinit(void)
double value = i / 4;
double f, fm;
int e, m;
- f = value * cbrtf(value) * pow(2, (i & 3) * 0.25);
+ f = value / IMDCT_SCALAR * cbrtf(value) * pow(2, (i & 3) * 0.25);
fm = frexp(f, &e);
m = (uint32_t)(fm * (1LL << 31) + 0.5);
e += FRAC_BITS - 31 + 5 - 100;
@@ -58,7 +59,7 @@ static void mpegaudio_tableinit(void)
}
for (exponent = 0; exponent < 512; exponent++) {
for (value = 0; value < 16; value++) {
- double f = (double)value * cbrtf(value) * pow(2, (exponent - 400) * 0.25 + FRAC_BITS + 5);
+ double f = (double)value * cbrtf(value) * pow(2, (exponent - 400) * 0.25 + FRAC_BITS + 5) / IMDCT_SCALAR;
expval_table_fixed[exponent][value] = llrint(f);
expval_table_float[exponent][value] = f;
}