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avcodec/rdft: remove sintable 

It is redundant with costable. The first half of sintable is
identical with the second half of costable. The second half
of sintable is negative value of the first half of sintable.

The computation is changed to handle sign of sin values, in
C code and ARM assembly code.

Signed-off-by: Muhammad Faiz <mfcc64@gmail.com>
tags/n3.4
Muhammad Faiz 8 years ago
parent
e7d977b446
commit
0780ad9c68
4 changed files with 36 additions and 74 deletions
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  1. +1
    -2
      libavcodec/Makefile
  2. +9
    -4
      libavcodec/arm/rdft_neon.S
  3. +24
    -44
      libavcodec/rdft.c
  4. +2
    -24
      libavcodec/rdft.h

+ 1
- 2
libavcodec/Makefile View File

@@ -122,8 +122,7 @@ OBJS-$(CONFIG_QSV) += qsv.o
OBJS-$(CONFIG_QSVDEC) += qsvdec.o
OBJS-$(CONFIG_QSVENC) += qsvenc.o
OBJS-$(CONFIG_RANGECODER) += rangecoder.o
RDFT-OBJS-$(CONFIG_HARDCODED_TABLES) += sin_tables.o
OBJS-$(CONFIG_RDFT) += rdft.o $(RDFT-OBJS-yes)
OBJS-$(CONFIG_RDFT) += rdft.o
OBJS-$(CONFIG_RV34DSP) += rv34dsp.o
OBJS-$(CONFIG_SHARED) += log2_tab.o reverse.o
OBJS-$(CONFIG_SINEWIN) += sinewin.o sinewin_fixed.o


+ 9
- 4
libavcodec/arm/rdft_neon.S View File

@@ -30,18 +30,21 @@ function ff_rdft_calc_neon, export=1

lsls r6, r6, #31
bne 1f
add r0, r4, #20
add r0, r4, #24
bl X(ff_fft_permute_neon)
add r0, r4, #20
add r0, r4, #24
mov r1, r5
bl X(ff_fft_calc_neon)
1:
ldr r12, [r4, #0] @ nbits
mov r2, #1
ldr r8, [r4, #20] @ negative_sin
lsl r12, r2, r12
add r0, r5, #8
lsl r8, r8, #31
add r1, r5, r12, lsl #2
lsr r12, r12, #2
vdup.32 d26, r8
ldr r2, [r4, #12] @ tcos
sub r12, r12, #2
ldr r3, [r4, #16] @ tsin
@@ -55,6 +58,7 @@ function ff_rdft_calc_neon, export=1
vld1.32 {d5}, [r3,:64]! @ tsin[i]
vmov.f32 d18, #0.5 @ k1
vdup.32 d19, r6
veor d5, d26, d5
pld [r0, #32]
veor d19, d18, d19 @ k2
vmov.i32 d16, #0
@@ -90,6 +94,7 @@ function ff_rdft_calc_neon, export=1
vld1.32 {d5}, [r3,:64]! @ tsin[i]
veor d24, d22, d17 @ ev.re,-ev.im
vrev64.32 d3, d23 @ od.re, od.im
veor d5, d26, d5
pld [r2, #32]
veor d2, d3, d16 @ -od.re, od.im
pld [r3, #32]
@@ -140,10 +145,10 @@ function ff_rdft_calc_neon, export=1

vmul.f32 d22, d22, d18
vst1.32 {d22}, [r5,:64]
add r0, r4, #20
add r0, r4, #24
mov r1, r5
bl X(ff_fft_permute_neon)
add r0, r4, #20
add r0, r4, #24
mov r1, r5
pop {r4-r8,lr}
b X(ff_fft_calc_neon)


+ 24
- 44
libavcodec/rdft.c View File

@@ -28,28 +28,6 @@
* (Inverse) Real Discrete Fourier Transforms.
*/

/* sin(2*pi*x/n) for 0<=x<n/4, followed by n/2<=x<3n/4 */
#if !CONFIG_HARDCODED_TABLES
SINTABLE(16);
SINTABLE(32);
SINTABLE(64);
SINTABLE(128);
SINTABLE(256);
SINTABLE(512);
SINTABLE(1024);
SINTABLE(2048);
SINTABLE(4096);
SINTABLE(8192);
SINTABLE(16384);
SINTABLE(32768);
SINTABLE(65536);
#endif
static SINTABLE_CONST FFTSample * const ff_sin_tabs[] = {
NULL, NULL, NULL, NULL,
ff_sin_16, ff_sin_32, ff_sin_64, ff_sin_128, ff_sin_256, ff_sin_512, ff_sin_1024,
ff_sin_2048, ff_sin_4096, ff_sin_8192, ff_sin_16384, ff_sin_32768, ff_sin_65536,
};

/** Map one real FFT into two parallel real even and odd FFTs. Then interleave
* the two real FFTs into one complex FFT. Unmangle the results.
* ref: http://www.engineeringproductivitytools.com/stuff/T0001/PT10.HTM
@@ -73,20 +51,29 @@ static void rdft_calc_c(RDFTContext *s, FFTSample *data)
ev.re = data[0];
data[0] = ev.re+data[1];
data[1] = ev.re-data[1];
for (i = 1; i < (n>>2); i++) {
i1 = 2*i;
i2 = n-i1;
/* Separate even and odd FFTs */
ev.re = k1*(data[i1 ]+data[i2 ]);
od.im = -k2*(data[i1 ]-data[i2 ]);
ev.im = k1*(data[i1+1]-data[i2+1]);
od.re = k2*(data[i1+1]+data[i2+1]);
/* Apply twiddle factors to the odd FFT and add to the even FFT */
data[i1 ] = ev.re + od.re*tcos[i] - od.im*tsin[i];
data[i1+1] = ev.im + od.im*tcos[i] + od.re*tsin[i];
data[i2 ] = ev.re - od.re*tcos[i] + od.im*tsin[i];
data[i2+1] = -ev.im + od.im*tcos[i] + od.re*tsin[i];

#define RDFT_UNMANGLE(sign0, sign1) \
for (i = 1; i < (n>>2); i++) { \
i1 = 2*i; \
i2 = n-i1; \
/* Separate even and odd FFTs */ \
ev.re = k1*(data[i1 ]+data[i2 ]); \
od.im = -k2*(data[i1 ]-data[i2 ]); \
ev.im = k1*(data[i1+1]-data[i2+1]); \
od.re = k2*(data[i1+1]+data[i2+1]); \
/* Apply twiddle factors to the odd FFT and add to the even FFT */ \
data[i1 ] = ev.re + od.re*tcos[i] sign0 od.im*tsin[i]; \
data[i1+1] = ev.im + od.im*tcos[i] sign1 od.re*tsin[i]; \
data[i2 ] = ev.re - od.re*tcos[i] sign1 od.im*tsin[i]; \
data[i2+1] = -ev.im + od.im*tcos[i] sign1 od.re*tsin[i]; \
}

if (s->negative_sin) {
RDFT_UNMANGLE(+,-)
} else {
RDFT_UNMANGLE(-,+)
}

data[2*i+1]=s->sign_convention*data[2*i+1];
if (s->inverse) {
data[0] *= k1;
@@ -104,6 +91,7 @@ av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans)
s->nbits = nbits;
s->inverse = trans == IDFT_C2R || trans == DFT_C2R;
s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1;
s->negative_sin = trans == DFT_C2R || trans == DFT_R2C;

if (nbits < 4 || nbits > 16)
return AVERROR(EINVAL);
@@ -113,15 +101,7 @@ av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans)

ff_init_ff_cos_tabs(nbits);
s->tcos = ff_cos_tabs[nbits];
s->tsin = ff_sin_tabs[nbits]+(trans == DFT_R2C || trans == DFT_C2R)*(n>>2);
#if !CONFIG_HARDCODED_TABLES
{
int i;
const double theta = (trans == DFT_R2C || trans == DFT_C2R ? -1 : 1) * 2 * M_PI / n;
for (i = 0; i < (n >> 2); i++)
s->tsin[i] = sin(i * theta);
}
#endif
s->tsin = ff_cos_tabs[nbits] + (n >> 2);
s->rdft_calc = rdft_calc_c;

if (ARCH_ARM) ff_rdft_init_arm(s);


+ 2
- 24
libavcodec/rdft.h View File

@@ -25,29 +25,6 @@
#include "config.h"
#include "fft.h"

#if CONFIG_HARDCODED_TABLES
# define SINTABLE_CONST const
#else
# define SINTABLE_CONST
#endif

#define SINTABLE(size) \
SINTABLE_CONST DECLARE_ALIGNED(16, FFTSample, ff_sin_##size)[size/2]

extern SINTABLE(16);
extern SINTABLE(32);
extern SINTABLE(64);
extern SINTABLE(128);
extern SINTABLE(256);
extern SINTABLE(512);
extern SINTABLE(1024);
extern SINTABLE(2048);
extern SINTABLE(4096);
extern SINTABLE(8192);
extern SINTABLE(16384);
extern SINTABLE(32768);
extern SINTABLE(65536);

struct RDFTContext {
int nbits;
int inverse;
@@ -55,7 +32,8 @@ struct RDFTContext {

/* pre/post rotation tables */
const FFTSample *tcos;
SINTABLE_CONST FFTSample *tsin;
const FFTSample *tsin;
int negative_sin;
FFTContext fft;
void (*rdft_calc)(struct RDFTContext *s, FFTSample *z);
};


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