[FFmpeg-devel] [PATCH] Common fixed-point ACELP routines (1/3) - math
Vladimir Voroshilov
voroshil
Fri Apr 25 09:20:46 CEST 2008
On Fri, Apr 25, 2008 at 12:19 PM, Vladimir Voroshilov <voroshil at gmail.com> wrote:
> Michael Niedermayer wrote:
>
>
> > following is a tiny bit more accurate and doesnt need the 3rd table:
>
> [...]
>
>
> > Note, yes the output is scaled different again
>
> Updated.
>
>
> > > +/**
> > > + * \brief multiplies 32-bit integer by another 16-bit and divides result by 2^15
> > > + * \param var_q24 32-bit integer
> > > + * \param var_15 16-bit integer
> > > + *
> > > + * \return result of (var_q24 * var_q15 >> 15) with clipping to [INT_MIN; INT_MAX] range
> > > + */
> > > +static inline int mul_32_16(int var_q24, int16_t var_q15)
> > > +{
> > > + return (((int64_t)var_q24 * (int64_t)var_q15) >> 15);
> > > +}
> >
> > now this looks like it belongs to libavcodec/mathops.h
>
> separate patch is attached.
>
>
> > > +/**
> > > + * \brief Calculates sum of array elements multiplications
> > > + * \param speech array with input data
> > > + * \param cycles number elements to proceed
> > > + * \param offset offset for calculation sum of s[i]*s[i+offset]
> > > + * \param shift right shift by this value will be done before multiplication
> > > + *
> > > + * \return sum of multiplications
> > > + *
> > > + * \note array must be at least length+offset long!
> > > + */
> > > +static int sum_of_squares(const int16_t* speech, int cycles, int offset, int shift)
> > > +{
> > > + const int16_t* speech_end;
> > > + int sum = 0;
> > > +
> > > + for(speech_end=speech+cycles; speech<speech_end; speech++)
> > > + sum += (speech[0] * speech[offset]) >> (shift << 1);
> >
> > IMHO the shift << 1 should be done outside this function
>
> Fixed.
>
>
>
acelp_math_26.diff in previous mail contains unrelated code.
Please ignore it.
This is right one.
P.S. i did not attach math_opts_27.diff since it is not changed.
--
Regards,
Vladimir Voroshilov mailto:voroshil at gmail.com
JID: voroshil at gmail.com, voroshil at jabber.ru
ICQ: 95587719
-------------- next part --------------
diff --git a/libavcodec/acelp_math.c b/libavcodec/acelp_math.c
new file mode 100644
index 0000000..05c699f
--- /dev/null
+++ b/libavcodec/acelp_math.c
@@ -0,0 +1,197 @@
+/*
+ * Various fixed-point math operations
+ *
+ * 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 <inttypes.h>
+#include <limits.h>
+#include <assert.h>
+
+#include "avcodec.h"
+#include "acelp_math.h"
+
+#ifdef G729_BITEXACT
+/**
+ * Cosine table: base_cos[i] = (1<<15) * cos(i*PI/64)
+ */
+static const int16_t base_cos[64] =
+{
+ 32767, 32729, 32610, 32413, 32138, 31786, 31357, 30853,
+ 30274, 29622, 28899, 28106, 27246, 26320, 25330, 24279,
+ 23170, 22006, 20788, 19520, 18205, 16846, 15447, 14010,
+ 12540, 11039, 9512, 7962, 6393, 4808, 3212, 1608,
+ 0, -1608, -3212, -4808, -6393, -7962, -9512, -11039,
+ -12540, -14010, -15447, -16846, -18205, -19520, -20788, -22006,
+ -23170, -24279, -25330, -26320, -27246, -28106, -28899, -29622,
+ -30274, -30853, -31357, -31786, -32138, -32413, -32610, -32729
+};
+
+/**
+ * Slope used to compute cos(x)
+ *
+ * cos(ind*64+offset) = base_cos[ind]+offset*slope_cos[ind]
+ * values multiplied by 1<<19
+ */
+static const int16_t slope_cos[64] =
+{
+ -632, -1893, -3150, -4399, -5638, -6863, -8072, -9261,
+ -10428, -11570, -12684, -13767, -14817, -15832, -16808, -17744,
+ -18637, -19486, -20287, -21039, -21741, -22390, -22986, -23526,
+ -24009, -24435, -24801, -25108, -25354, -25540, -25664, -25726,
+ -25726, -25664, -25540, -25354, -25108, -24801, -24435, -24009,
+ -23526, -22986, -22390, -21741, -21039, -20287, -19486, -18637,
+ -17744, -16808, -15832, -14817, -13767, -12684, -11570, -10428,
+ -9261, -8072, -6863, -5638, -4399, -3150, -1893, -632
+};
+
+/**
+ * Table used to compute exp2(x)
+ *
+ * tab_exp2[i] = (1<<14) * exp2(i/32) = 2^(i/32) i=0..32
+ */
+static const uint16_t tab_exp2[33] =
+{
+ 16384, 16743, 17109, 17484, 17867, 18258, 18658, 19066, 19484, 19911,
+ 20347, 20792, 21247, 21713, 22188, 22674, 23170, 23678, 24196, 24726,
+ 25268, 25821, 26386, 26964, 27554, 28158, 28774, 29405, 30048, 30706,
+ 31379, 32066, 32767
+};
+
+int16_t ff_cos(uint16_t arg)
+{
+ uint8_t offset= arg;
+ uint8_t ind = arg >> 8;
+
+ assert(arg < 0x4000);
+
+ return FFMAX(base_cos[ind] + ((slope_cos[ind] * offset) >> 12), -0x8000);
+}
+
+int ff_exp2(uint16_t power)
+{
+ uint16_t frac_x0;
+ uint16_t frac_dx;
+ int result;
+
+ assert(power <= 0x7fff);
+
+ frac_x0 = power >> 10;
+ frac_dx = (power & 0x03ff) << 5;
+
+ result = tab_exp2[frac_x0] << 15;
+ result += frac_dx * (tab_exp2[frac_x0+1] - tab_exp2[frac_x0]);
+
+ return result >> 10;
+}
+
+#else // G729_BITEXACT
+
+/**
+ * Cosine table: base_cos[i] = (1<<15) * cos(i*PI/64)
+ */
+static const int16_t tab_cos[65] =
+{
+ 32767, 32738, 32617, 32421, 32145, 31793, 31364, 30860,
+ 30280, 29629, 28905, 28113, 27252, 26326, 25336, 24285,
+ 23176, 22011, 20793, 19525, 18210, 16851, 15451, 14014,
+ 12543, 11043, 9515, 7965, 6395, 4810, 3214, 1609,
+ 1, -1607, -3211, -4808, -6393, -7962, -9513, -11040,
+ -12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
+ -23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
+ -30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
+};
+
+static const uint16_t exp2a[]=
+{
+ 0, 1435, 2901, 4400, 5931, 7496, 9096, 10730,
+ 12400, 14106, 15850, 17632, 19454, 21315, 23216, 25160,
+ 27146, 29175, 31249, 33368, 35534, 37747, 40009, 42320,
+ 44682, 47095, 49562, 52082, 54657, 57289, 59979, 62727,
+};
+
+static const uint16_t exp2b[]=
+{
+ 3, 712, 1424, 2134, 2845, 3557, 4270, 4982,
+ 5696, 6409, 7124, 7839, 8554, 9270, 9986, 10704,
+ 11421, 12138, 12857, 13576, 14295, 15014, 15734, 16455,
+ 17176, 17898, 18620, 19343, 20066, 20790, 21514, 22238,
+};
+
+int16_t ff_cos(uint16_t arg)
+{
+ uint8_t offset= arg;
+ uint8_t ind = arg >> 8;
+
+ assert(arg <= 0x3fff);
+
+ return tab_cos[ind] + (offset * (tab_cos[ind+1] - tab_cos[ind]) >> 8);
+}
+
+int ff_exp2(uint16_t power)
+{
+ unsigned int result= exp2a[power>>10] + 0x10000;
+
+ assert(arg <= 0x7fff);
+
+ result= (result<<3) + ((result*exp2b[(power>>5)&31])>>17);
+ return result + ((result*(power&31)*89)>>22);
+}
+
+#endif // else G729_BITEXACT
+
+/**
+ * Table used to compute log2(x)
+ *
+ * tab_log2[i] = (1<<15) * log2(1 + i/32), i=0..32
+ */
+static const uint16_t tab_log2[33] =
+{
+#ifdef G729_BITEXACT
+ 0, 1455, 2866, 4236, 5568, 6863, 8124, 9352,
+ 10549, 11716, 12855, 13967, 15054, 16117, 17156, 18172,
+ 19167, 20142, 21097, 22033, 22951, 23852, 24735, 25603,
+ 26455, 27291, 28113, 28922, 29716, 30497, 31266, 32023, 32767,
+#else
+ 4, 1459, 2870, 4240, 5572, 6867, 8127, 9355,
+ 10552, 11719, 12858, 13971, 15057, 16120, 17158, 18175,
+ 19170, 20145, 21100, 22036, 22954, 23854, 24738, 25605,
+ 26457, 27294, 28116, 28924, 29719, 30500, 31269, 32025, 32769,
+#endif
+};
+
+int ff_log2(uint32_t value)
+{
+ uint8_t power_int;
+ uint8_t frac_x0;
+ uint16_t frac_dx;
+
+ // Stripping zeros from beginning
+ power_int = av_log2(value);
+ value <<= (31 - power_int);
+
+ // b31 is always non-zero now
+ frac_x0 = (value & 0x7c000000) >> 26; // b26-b31 and [32..63] -> [0..31]
+ frac_dx = (value & 0x03fff800) >> 11;
+
+ value = tab_log2[frac_x0];
+ value += (frac_dx * (tab_log2[frac_x0+1] - tab_log2[frac_x0])) >> 15;
+
+ return (power_int << 15) + value;
+}
diff --git a/libavcodec/acelp_math.h b/libavcodec/acelp_math.h
new file mode 100644
index 0000000..01fc399
--- /dev/null
+++ b/libavcodec/acelp_math.h
@@ -0,0 +1,74 @@
+/*
+ * Various fixed-point math operations
+ *
+ * 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
+ */
+
+#ifndef FFMPEG_ACELP_MATH_H
+#define FFMPEG_ACELP_MATH_H
+
+/**
+ * \brief fixed-point implementation of cosine in [0; PI) domain
+ * \param arg fixed-point cosine argument, 0 <= arg < 0x4000
+ *
+ * \return value of (1<<15) * cos(arg * PI / (1<<14)), -0x8000 <= result <= 0x7fff
+ */
+int16_t ff_cos(uint16_t arg);
+
+/**
+ * \brief fixed-point implementation of exp2(x) in [0; 1] domain
+ * \param power argument to exp2, 0 <= power <= 0x7fff
+ *
+ * \return value of (1<<20) * exp2(power / (1<<15))
+ * 0x8000c <= result <= 0xfffea
+ */
+int ff_exp2(uint16_t power);
+
+/**
+ * \brief Calculates log2(x)
+ * \param value function argument, 0 < value <= 7fff ffff
+ *
+ * \return value of (1<<15) * log2(value)
+ */
+int ff_log2(uint32_t value);
+
+/**
+ * \brief Calculates sum of array elements multiplications
+ * \param speech array with input data
+ * \param cycles number elements to proceed
+ * \param offset offset for calculation sum of s[i]*s[i+offset]
+ * \param shift right shift by this value will be done before multiplication
+ *
+ * \return sum of multiplications
+ *
+ * \note array must be at least length+offset long!
+ */
+static int sum_of_squares(const int16_t* speech, int cycles, int offset, int shift)
+{
+ const int16_t* speech_end;
+ int sum = 0;
+
+ shift <<= 1;
+ for(speech_end=speech+cycles; speech<speech_end; speech++)
+ sum += (speech[0] * speech[offset]) >> shift;
+
+ return sum;
+}
+
+#endif // FFMPEG_ACELP_MATH_H
More information about the ffmpeg-devel
mailing list