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Reduce multiplier precision for warp least squares
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Includes reordering and other clamping changes, as well as
changes to reduce multiplier precision.

cam_lowres (60 frames): -0.092% BDRATE improvement in
--disable-cdef --disable-global-motion --disable-ext-tx
configuation.

Change-Id: I0660c45b44fcd5a193534d8dadd1aa1ae5c5e27a
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@debargha
debargha committed Jun 27, 2017
1 parent 5128109 commit f053cba
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Showing 3 changed files with 106 additions and 35 deletions.
4 changes: 4 additions & 0 deletions aom_dsp/aom_dsp_common.h
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,10 @@ static INLINE int clamp(int value, int low, int high) {
return value < low ? low : (value > high ? high : value);
}

static INLINE int64_t clamp64(int64_t value, int64_t low, int64_t high) {
return value < low ? low : (value > high ? high : value);
}

static INLINE double fclamp(double value, double low, double high) {
return value < low ? low : (value > high ? high : value);
}
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5 changes: 2 additions & 3 deletions av1/common/mv.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,9 +44,8 @@ typedef struct mv32 {
#define WARPEDMODEL_ROW3HOMO_PREC_BITS 16

#define WARPEDMODEL_TRANS_CLAMP (128 << WARPEDMODEL_PREC_BITS)
#define WARPEDMODEL_DIAGAFFINE_CLAMP (1 << (WARPEDMODEL_PREC_BITS + 1))
#define WARPEDMODEL_NONDIAGAFFINE_CLAMP (1 << (WARPEDMODEL_PREC_BITS - 1))
#define WARPEDMODEL_ROW3HOMO_CLAMP (1 << (WARPEDMODEL_PREC_BITS - 1))
#define WARPEDMODEL_NONDIAGAFFINE_CLAMP (1 << (WARPEDMODEL_PREC_BITS - 3))
#define WARPEDMODEL_ROW3HOMO_CLAMP (1 << (WARPEDMODEL_PREC_BITS - 2))

// Bits of subpel precision for warped interpolation
#define WARPEDPIXEL_PREC_BITS 6
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132 changes: 100 additions & 32 deletions av1/common/warped_motion.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1747,6 +1747,83 @@ void av1_warp_plane(WarpedMotionParams *wm,
#define LS_PRODUCT2(a, b) \
(((a) * (b)*4 + ((a) + (b)) * 2 * LS_STEP + LS_STEP * LS_STEP * 2) >> 2)

#define USE_LIMITED_PREC_MULT 0

#if USE_LIMITED_PREC_MULT

#define MUL_PREC_BITS 16
static uint16_t resolve_multiplier_64(uint64_t D, int16_t *shift) {
int msb = 0;
uint16_t mult = 0;
*shift = 0;
if (D != 0) {
msb = (int16_t)((D >> 32) ? get_msb((unsigned int)(D >> 32)) + 32
: get_msb((unsigned int)D));
if (msb >= MUL_PREC_BITS) {
mult = (uint16_t)ROUND_POWER_OF_TWO_64(D, msb + 1 - MUL_PREC_BITS);
*shift = msb + 1 - MUL_PREC_BITS;
} else {
mult = (uint16_t)D;
*shift = 0;
}
}
return mult;
}

static int32_t get_mult_shift_ndiag(int64_t Px, int16_t iDet, int shift) {
int32_t ret;
int16_t mshift;
uint16_t Mul = resolve_multiplier_64(llabs(Px), &mshift);
int32_t v = (int32_t)Mul * (int32_t)iDet * (Px < 0 ? -1 : 1);
shift -= mshift;
if (shift > 0) {
return (int32_t)clamp(ROUND_POWER_OF_TWO_SIGNED(v, shift),
-WARPEDMODEL_NONDIAGAFFINE_CLAMP + 1,
WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
} else {
return (int32_t)clamp(v * (1 << (-shift)),
-WARPEDMODEL_NONDIAGAFFINE_CLAMP + 1,
WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
}
return ret;
}

static int32_t get_mult_shift_diag(int64_t Px, int16_t iDet, int shift) {
int16_t mshift;
uint16_t Mul = resolve_multiplier_64(llabs(Px), &mshift);
int32_t v = (int32_t)Mul * (int32_t)iDet * (Px < 0 ? -1 : 1);
shift -= mshift;
if (shift > 0) {
return (int32_t)clamp(
ROUND_POWER_OF_TWO_SIGNED(v, shift),
(1 << WARPEDMODEL_PREC_BITS) - WARPEDMODEL_NONDIAGAFFINE_CLAMP + 1,
(1 << WARPEDMODEL_PREC_BITS) + WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
} else {
return (int32_t)clamp(
v * (1 << (-shift)),
(1 << WARPEDMODEL_PREC_BITS) - WARPEDMODEL_NONDIAGAFFINE_CLAMP + 1,
(1 << WARPEDMODEL_PREC_BITS) + WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
}
}

#else

static int32_t get_mult_shift_ndiag(int64_t Px, int16_t iDet, int shift) {
int64_t v = Px * (int64_t)iDet;
return (int32_t)clamp64(ROUND_POWER_OF_TWO_SIGNED_64(v, shift),
-WARPEDMODEL_NONDIAGAFFINE_CLAMP + 1,
WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
}

static int32_t get_mult_shift_diag(int64_t Px, int16_t iDet, int shift) {
int64_t v = Px * (int64_t)iDet;
return (int32_t)clamp64(
ROUND_POWER_OF_TWO_SIGNED_64(v, shift),
(1 << WARPEDMODEL_PREC_BITS) - WARPEDMODEL_NONDIAGAFFINE_CLAMP + 1,
(1 << WARPEDMODEL_PREC_BITS) + WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
}
#endif // USE_LIMITED_PREC_MULT

static int find_affine_int(int np, int *pts1, int *pts2, BLOCK_SIZE bsize,
int mvy, int mvx, WarpedMotionParams *wm, int mi_row,
int mi_col) {
Expand All @@ -1757,8 +1834,10 @@ static int find_affine_int(int np, int *pts1, int *pts2, BLOCK_SIZE bsize,

const int bw = block_size_wide[bsize];
const int bh = block_size_high[bsize];
const int suy = (mi_row * MI_SIZE + AOMMAX(bh, MI_SIZE) / 2 - 1) * 8;
const int sux = (mi_col * MI_SIZE + AOMMAX(bw, MI_SIZE) / 2 - 1) * 8;
const int isuy = (mi_row * MI_SIZE + AOMMAX(bh, MI_SIZE) / 2 - 1);
const int isux = (mi_col * MI_SIZE + AOMMAX(bw, MI_SIZE) / 2 - 1);
const int suy = isuy * 8;
const int sux = isux * 8;
const int duy = suy + mvy;
const int dux = sux + mvx;

Expand Down Expand Up @@ -1845,38 +1924,27 @@ static int find_affine_int(int np, int *pts1, int *pts2, BLOCK_SIZE bsize,
shift = 0;
}

int64_t v;
v = Px[0] * (int64_t)iDet;
wm->wmmat[2] = (int32_t)(ROUND_POWER_OF_TWO_SIGNED_64(v, shift));
v = Px[1] * (int64_t)iDet;
wm->wmmat[3] = (int32_t)(ROUND_POWER_OF_TWO_SIGNED_64(v, shift));
v = ((int64_t)dux * (1 << WARPEDMODEL_PREC_BITS)) -
(int64_t)sux * wm->wmmat[2] - (int64_t)suy * wm->wmmat[3];
wm->wmmat[0] = (int32_t)(ROUND_POWER_OF_TWO_SIGNED(v, 3));

v = Py[0] * (int64_t)iDet;
wm->wmmat[4] = (int32_t)(ROUND_POWER_OF_TWO_SIGNED_64(v, shift));
v = Py[1] * (int64_t)iDet;
wm->wmmat[5] = (int32_t)(ROUND_POWER_OF_TWO_SIGNED_64(v, shift));
v = ((int64_t)duy * (1 << WARPEDMODEL_PREC_BITS)) -
(int64_t)sux * wm->wmmat[4] - (int64_t)suy * wm->wmmat[5];
wm->wmmat[1] = (int32_t)(ROUND_POWER_OF_TWO_SIGNED(v, 3));
wm->wmmat[2] = get_mult_shift_diag(Px[0], iDet, shift);
wm->wmmat[3] = get_mult_shift_ndiag(Px[1], iDet, shift);
wm->wmmat[4] = get_mult_shift_ndiag(Py[0], iDet, shift);
wm->wmmat[5] = get_mult_shift_diag(Py[1], iDet, shift);

// Note: In the vx, vy expressions below, the max value of each of the
// 2nd and 3rd terms are (2^16 - 1) * (2^13 - 1). That leaves enough room
// for the first term so that the overall sum in the worst case fits
// within 32 bits overall.
int32_t vx = mvx * (1 << (WARPEDMODEL_PREC_BITS - 3)) -
(isux * (wm->wmmat[2] - (1 << WARPEDMODEL_PREC_BITS)) +
isuy * wm->wmmat[3]);
int32_t vy = mvy * (1 << (WARPEDMODEL_PREC_BITS - 3)) -
(isux * wm->wmmat[4] +
isuy * (wm->wmmat[5] - (1 << WARPEDMODEL_PREC_BITS)));
wm->wmmat[0] =
clamp(vx, -WARPEDMODEL_TRANS_CLAMP, WARPEDMODEL_TRANS_CLAMP - 1);
wm->wmmat[1] =
clamp(vy, -WARPEDMODEL_TRANS_CLAMP, WARPEDMODEL_TRANS_CLAMP - 1);

wm->wmmat[6] = wm->wmmat[7] = 0;

// Clamp values
wm->wmmat[0] = clamp(wm->wmmat[0], -WARPEDMODEL_TRANS_CLAMP,
WARPEDMODEL_TRANS_CLAMP - 1);
wm->wmmat[1] = clamp(wm->wmmat[1], -WARPEDMODEL_TRANS_CLAMP,
WARPEDMODEL_TRANS_CLAMP - 1);
wm->wmmat[2] = clamp(wm->wmmat[2], -WARPEDMODEL_DIAGAFFINE_CLAMP,
WARPEDMODEL_DIAGAFFINE_CLAMP - 1);
wm->wmmat[5] = clamp(wm->wmmat[5], -WARPEDMODEL_DIAGAFFINE_CLAMP,
WARPEDMODEL_DIAGAFFINE_CLAMP - 1);
wm->wmmat[3] = clamp(wm->wmmat[3], -WARPEDMODEL_NONDIAGAFFINE_CLAMP,
WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
wm->wmmat[4] = clamp(wm->wmmat[4], -WARPEDMODEL_NONDIAGAFFINE_CLAMP,
WARPEDMODEL_NONDIAGAFFINE_CLAMP - 1);
return 0;
}

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