File: //usr/src/x264-snapshot-20120103-2245-stable/encoder/rdo.c
/*****************************************************************************
* rdo.c: rate-distortion optimization
*****************************************************************************
* Copyright (C) 2005-2011 x264 project
*
* Authors: Loren Merritt <lorenm@u.washington.edu>
* Jason Garrett-Glaser <darkshikari@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111, USA.
*
* This program is also available under a commercial proprietary license.
* For more information, contact us at licensing@x264.com.
*****************************************************************************/
/* duplicate all the writer functions, just calculating bit cost
* instead of writing the bitstream.
* TODO: use these for fast 1st pass too. */
#define RDO_SKIP_BS 1
/* Transition and size tables for abs<9 MVD and residual coding */
/* Consist of i_prefix-2 1s, one zero, and a bypass sign bit */
static uint8_t cabac_transition_unary[15][128];
static uint16_t cabac_size_unary[15][128];
/* Transition and size tables for abs>9 MVD */
/* Consist of 5 1s and a bypass sign bit */
static uint8_t cabac_transition_5ones[128];
static uint16_t cabac_size_5ones[128];
/* CAVLC: produces exactly the same bit count as a normal encode */
/* this probably still leaves some unnecessary computations */
#define bs_write1(s,v) ((s)->i_bits_encoded += 1)
#define bs_write(s,n,v) ((s)->i_bits_encoded += (n))
#define bs_write_ue(s,v) ((s)->i_bits_encoded += bs_size_ue(v))
#define bs_write_se(s,v) ((s)->i_bits_encoded += bs_size_se(v))
#define bs_write_te(s,v,l) ((s)->i_bits_encoded += bs_size_te(v,l))
#define x264_macroblock_write_cavlc static x264_macroblock_size_cavlc
#include "cavlc.c"
/* CABAC: not exactly the same. x264_cabac_size_decision() keeps track of
* fractional bits, but only finite precision. */
#undef x264_cabac_encode_decision
#undef x264_cabac_encode_decision_noup
#undef x264_cabac_encode_bypass
#undef x264_cabac_encode_terminal
#define x264_cabac_encode_decision(c,x,v) x264_cabac_size_decision(c,x,v)
#define x264_cabac_encode_decision_noup(c,x,v) x264_cabac_size_decision_noup(c,x,v)
#define x264_cabac_encode_terminal(c) ((c)->f8_bits_encoded += 7)
#define x264_cabac_encode_bypass(c,v) ((c)->f8_bits_encoded += 256)
#define x264_cabac_encode_ue_bypass(c,e,v) ((c)->f8_bits_encoded += (bs_size_ue_big(v+(1<<e)-1)-e)<<8)
#define x264_macroblock_write_cabac static x264_macroblock_size_cabac
#include "cabac.c"
#define COPY_CABAC h->mc.memcpy_aligned( &cabac_tmp.f8_bits_encoded, &h->cabac.f8_bits_encoded, \
sizeof(x264_cabac_t) - offsetof(x264_cabac_t,f8_bits_encoded) - (CHROMA444 ? 0 : (1024+12)-460) )
#define COPY_CABAC_PART( pos, size )\
memcpy( &cb->state[pos], &h->cabac.state[pos], size )
static ALWAYS_INLINE uint64_t cached_hadamard( x264_t *h, int size, int x, int y )
{
static const uint8_t hadamard_shift_x[4] = {4, 4, 3, 3};
static const uint8_t hadamard_shift_y[4] = {4-0, 3-0, 4-1, 3-1};
static const uint8_t hadamard_offset[4] = {0, 1, 3, 5};
int cache_index = (x >> hadamard_shift_x[size]) + (y >> hadamard_shift_y[size])
+ hadamard_offset[size];
uint64_t res = h->mb.pic.fenc_hadamard_cache[cache_index];
if( res )
return res - 1;
else
{
pixel *fenc = h->mb.pic.p_fenc[0] + x + y*FENC_STRIDE;
res = h->pixf.hadamard_ac[size]( fenc, FENC_STRIDE );
h->mb.pic.fenc_hadamard_cache[cache_index] = res + 1;
return res;
}
}
static ALWAYS_INLINE int cached_satd( x264_t *h, int size, int x, int y )
{
static const uint8_t satd_shift_x[3] = {3, 2, 2};
static const uint8_t satd_shift_y[3] = {2-1, 3-2, 2-2};
static const uint8_t satd_offset[3] = {0, 8, 16};
ALIGNED_16( static pixel zero[16] ) = {0};
int cache_index = (x >> satd_shift_x[size - PIXEL_8x4]) + (y >> satd_shift_y[size - PIXEL_8x4])
+ satd_offset[size - PIXEL_8x4];
int res = h->mb.pic.fenc_satd_cache[cache_index];
if( res )
return res - 1;
else
{
pixel *fenc = h->mb.pic.p_fenc[0] + x + y*FENC_STRIDE;
int dc = h->pixf.sad[size]( fenc, FENC_STRIDE, zero, 0 ) >> 1;
res = h->pixf.satd[size]( fenc, FENC_STRIDE, zero, 0 ) - dc;
h->mb.pic.fenc_satd_cache[cache_index] = res + 1;
return res;
}
}
/* Psy RD distortion metric: SSD plus "Absolute Difference of Complexities" */
/* SATD and SA8D are used to measure block complexity. */
/* The difference between SATD and SA8D scores are both used to avoid bias from the DCT size. Using SATD */
/* only, for example, results in overusage of 8x8dct, while the opposite occurs when using SA8D. */
/* FIXME: Is there a better metric than averaged SATD/SA8D difference for complexity difference? */
/* Hadamard transform is recursive, so a SATD+SA8D can be done faster by taking advantage of this fact. */
/* This optimization can also be used in non-RD transform decision. */
static inline int ssd_plane( x264_t *h, int size, int p, int x, int y )
{
ALIGNED_16( static pixel zero[16] ) = {0};
int satd = 0;
pixel *fdec = h->mb.pic.p_fdec[p] + x + y*FDEC_STRIDE;
pixel *fenc = h->mb.pic.p_fenc[p] + x + y*FENC_STRIDE;
if( p == 0 && h->mb.i_psy_rd )
{
/* If the plane is smaller than 8x8, we can't do an SA8D; this probably isn't a big problem. */
if( size <= PIXEL_8x8 )
{
uint64_t fdec_acs = h->pixf.hadamard_ac[size]( fdec, FDEC_STRIDE );
uint64_t fenc_acs = cached_hadamard( h, size, x, y );
satd = abs((int32_t)fdec_acs - (int32_t)fenc_acs)
+ abs((int32_t)(fdec_acs>>32) - (int32_t)(fenc_acs>>32));
satd >>= 1;
}
else
{
int dc = h->pixf.sad[size]( fdec, FDEC_STRIDE, zero, 0 ) >> 1;
satd = abs(h->pixf.satd[size]( fdec, FDEC_STRIDE, zero, 0 ) - dc - cached_satd( h, size, x, y ));
}
satd = (satd * h->mb.i_psy_rd * h->mb.i_psy_rd_lambda + 128) >> 8;
}
return h->pixf.ssd[size](fenc, FENC_STRIDE, fdec, FDEC_STRIDE) + satd;
}
static inline int ssd_mb( x264_t *h )
{
int chroma_size = h->luma2chroma_pixel[PIXEL_16x16];
int chroma_ssd = ssd_plane(h, chroma_size, 1, 0, 0) + ssd_plane(h, chroma_size, 2, 0, 0);
chroma_ssd = ((uint64_t)chroma_ssd * h->mb.i_chroma_lambda2_offset + 128) >> 8;
return ssd_plane(h, PIXEL_16x16, 0, 0, 0) + chroma_ssd;
}
static int x264_rd_cost_mb( x264_t *h, int i_lambda2 )
{
int b_transform_bak = h->mb.b_transform_8x8;
int i_ssd;
int i_bits;
int type_bak = h->mb.i_type;
x264_macroblock_encode( h );
if( h->mb.b_deblock_rdo )
x264_macroblock_deblock( h );
i_ssd = ssd_mb( h );
if( IS_SKIP( h->mb.i_type ) )
{
i_bits = (1 * i_lambda2 + 128) >> 8;
}
else if( h->param.b_cabac )
{
x264_cabac_t cabac_tmp;
COPY_CABAC;
x264_macroblock_size_cabac( h, &cabac_tmp );
i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 32768 ) >> 16;
}
else
{
x264_macroblock_size_cavlc( h );
i_bits = ( h->out.bs.i_bits_encoded * i_lambda2 + 128 ) >> 8;
}
h->mb.b_transform_8x8 = b_transform_bak;
h->mb.i_type = type_bak;
return i_ssd + i_bits;
}
/* partition RD functions use 8 bits more precision to avoid large rounding errors at low QPs */
static uint64_t x264_rd_cost_subpart( x264_t *h, int i_lambda2, int i4, int i_pixel )
{
uint64_t i_ssd, i_bits;
x264_macroblock_encode_p4x4( h, i4 );
if( i_pixel == PIXEL_8x4 )
x264_macroblock_encode_p4x4( h, i4+1 );
if( i_pixel == PIXEL_4x8 )
x264_macroblock_encode_p4x4( h, i4+2 );
i_ssd = ssd_plane( h, i_pixel, 0, block_idx_x[i4]*4, block_idx_y[i4]*4 );
if( CHROMA444 )
{
int chromassd = ssd_plane( h, i_pixel, 1, block_idx_x[i4]*4, block_idx_y[i4]*4 )
+ ssd_plane( h, i_pixel, 2, block_idx_x[i4]*4, block_idx_y[i4]*4 );
chromassd = ((uint64_t)chromassd * h->mb.i_chroma_lambda2_offset + 128) >> 8;
i_ssd += chromassd;
}
if( h->param.b_cabac )
{
x264_cabac_t cabac_tmp;
COPY_CABAC;
x264_subpartition_size_cabac( h, &cabac_tmp, i4, i_pixel );
i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 128 ) >> 8;
}
else
i_bits = x264_subpartition_size_cavlc( h, i4, i_pixel );
return (i_ssd<<8) + i_bits;
}
uint64_t x264_rd_cost_part( x264_t *h, int i_lambda2, int i4, int i_pixel )
{
uint64_t i_ssd, i_bits;
int i8 = i4 >> 2;
if( i_pixel == PIXEL_16x16 )
{
int i_cost = x264_rd_cost_mb( h, i_lambda2 );
return i_cost;
}
if( i_pixel > PIXEL_8x8 )
return x264_rd_cost_subpart( h, i_lambda2, i4, i_pixel );
h->mb.i_cbp_luma = 0;
x264_macroblock_encode_p8x8( h, i8 );
if( i_pixel == PIXEL_16x8 )
x264_macroblock_encode_p8x8( h, i8+1 );
if( i_pixel == PIXEL_8x16 )
x264_macroblock_encode_p8x8( h, i8+2 );
int ssd_x = 8*(i8&1);
int ssd_y = 8*(i8>>1);
i_ssd = ssd_plane( h, i_pixel, 0, ssd_x, ssd_y );
int chromapix = h->luma2chroma_pixel[i_pixel];
int chromassd = ssd_plane( h, chromapix, 1, ssd_x>>CHROMA_H_SHIFT, ssd_y>>CHROMA_V_SHIFT )
+ ssd_plane( h, chromapix, 2, ssd_x>>CHROMA_H_SHIFT, ssd_y>>CHROMA_V_SHIFT );
i_ssd += ((uint64_t)chromassd * h->mb.i_chroma_lambda2_offset + 128) >> 8;
if( h->param.b_cabac )
{
x264_cabac_t cabac_tmp;
COPY_CABAC;
x264_partition_size_cabac( h, &cabac_tmp, i8, i_pixel );
i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 128 ) >> 8;
}
else
i_bits = x264_partition_size_cavlc( h, i8, i_pixel ) * i_lambda2;
return (i_ssd<<8) + i_bits;
}
static uint64_t x264_rd_cost_i8x8( x264_t *h, int i_lambda2, int i8, int i_mode, pixel edge[4][32] )
{
uint64_t i_ssd, i_bits;
int plane_count = CHROMA444 ? 3 : 1;
int i_qp = h->mb.i_qp;
h->mb.i_cbp_luma &= ~(1<<i8);
h->mb.b_transform_8x8 = 1;
for( int p = 0; p < plane_count; p++ )
{
x264_mb_encode_i8x8( h, p, i8, i_qp, i_mode, edge[p], 1 );
i_qp = h->mb.i_chroma_qp;
}
i_ssd = ssd_plane( h, PIXEL_8x8, 0, (i8&1)*8, (i8>>1)*8 );
if( CHROMA444 )
{
int chromassd = ssd_plane( h, PIXEL_8x8, 1, (i8&1)*8, (i8>>1)*8 )
+ ssd_plane( h, PIXEL_8x8, 2, (i8&1)*8, (i8>>1)*8 );
chromassd = ((uint64_t)chromassd * h->mb.i_chroma_lambda2_offset + 128) >> 8;
i_ssd += chromassd;
}
if( h->param.b_cabac )
{
x264_cabac_t cabac_tmp;
COPY_CABAC;
x264_partition_i8x8_size_cabac( h, &cabac_tmp, i8, i_mode );
i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 128 ) >> 8;
}
else
i_bits = x264_partition_i8x8_size_cavlc( h, i8, i_mode ) * i_lambda2;
return (i_ssd<<8) + i_bits;
}
static uint64_t x264_rd_cost_i4x4( x264_t *h, int i_lambda2, int i4, int i_mode )
{
uint64_t i_ssd, i_bits;
int plane_count = CHROMA444 ? 3 : 1;
int i_qp = h->mb.i_qp;
for( int p = 0; p < plane_count; p++ )
{
x264_mb_encode_i4x4( h, p, i4, i_qp, i_mode, 1 );
i_qp = h->mb.i_chroma_qp;
}
i_ssd = ssd_plane( h, PIXEL_4x4, 0, block_idx_x[i4]*4, block_idx_y[i4]*4 );
if( CHROMA444 )
{
int chromassd = ssd_plane( h, PIXEL_4x4, 1, block_idx_x[i4]*4, block_idx_y[i4]*4 )
+ ssd_plane( h, PIXEL_4x4, 2, block_idx_x[i4]*4, block_idx_y[i4]*4 );
chromassd = ((uint64_t)chromassd * h->mb.i_chroma_lambda2_offset + 128) >> 8;
i_ssd += chromassd;
}
if( h->param.b_cabac )
{
x264_cabac_t cabac_tmp;
COPY_CABAC;
x264_partition_i4x4_size_cabac( h, &cabac_tmp, i4, i_mode );
i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 128 ) >> 8;
}
else
i_bits = x264_partition_i4x4_size_cavlc( h, i4, i_mode ) * i_lambda2;
return (i_ssd<<8) + i_bits;
}
static uint64_t x264_rd_cost_chroma( x264_t *h, int i_lambda2, int i_mode, int b_dct )
{
uint64_t i_ssd, i_bits;
if( b_dct )
x264_mb_encode_chroma( h, 0, h->mb.i_chroma_qp );
int chromapix = h->luma2chroma_pixel[PIXEL_16x16];
i_ssd = ssd_plane( h, chromapix, 1, 0, 0 )
+ ssd_plane( h, chromapix, 2, 0, 0 );
h->mb.i_chroma_pred_mode = i_mode;
if( h->param.b_cabac )
{
x264_cabac_t cabac_tmp;
COPY_CABAC;
x264_chroma_size_cabac( h, &cabac_tmp );
i_bits = ( (uint64_t)cabac_tmp.f8_bits_encoded * i_lambda2 + 128 ) >> 8;
}
else
i_bits = x264_chroma_size_cavlc( h ) * i_lambda2;
return (i_ssd<<8) + i_bits;
}
/****************************************************************************
* Trellis RD quantization
****************************************************************************/
#define TRELLIS_SCORE_MAX ((uint64_t)1<<50)
#define CABAC_SIZE_BITS 8
#define SSD_WEIGHT_BITS 5
#define LAMBDA_BITS 4
/* precalculate the cost of coding various combinations of bits in a single context */
void x264_rdo_init( void )
{
for( int i_prefix = 0; i_prefix < 15; i_prefix++ )
{
for( int i_ctx = 0; i_ctx < 128; i_ctx++ )
{
int f8_bits = 0;
uint8_t ctx = i_ctx;
for( int i = 1; i < i_prefix; i++ )
f8_bits += x264_cabac_size_decision2( &ctx, 1 );
if( i_prefix > 0 && i_prefix < 14 )
f8_bits += x264_cabac_size_decision2( &ctx, 0 );
f8_bits += 1 << CABAC_SIZE_BITS; //sign
cabac_size_unary[i_prefix][i_ctx] = f8_bits;
cabac_transition_unary[i_prefix][i_ctx] = ctx;
}
}
for( int i_ctx = 0; i_ctx < 128; i_ctx++ )
{
int f8_bits = 0;
uint8_t ctx = i_ctx;
for( int i = 0; i < 5; i++ )
f8_bits += x264_cabac_size_decision2( &ctx, 1 );
f8_bits += 1 << CABAC_SIZE_BITS; //sign
cabac_size_5ones[i_ctx] = f8_bits;
cabac_transition_5ones[i_ctx] = ctx;
}
}
typedef struct
{
int64_t score;
int level_idx; // index into level_tree[]
uint8_t cabac_state[10]; //just the contexts relevant to coding abs_level_m1
} trellis_node_t;
// TODO:
// save cabac state between blocks?
// use trellis' RD score instead of x264_mb_decimate_score?
// code 8x8 sig/last flags forwards with deadzone and save the contexts at
// each position?
// change weights when using CQMs?
// possible optimizations:
// make scores fit in 32bit
// save quantized coefs during rd, to avoid a duplicate trellis in the final encode
// if trellissing all MBRD modes, finish SSD calculation so we can skip all of
// the normal dequant/idct/ssd/cabac
// the unquant_mf here is not the same as dequant_mf:
// in normal operation (dct->quant->dequant->idct) the dct and idct are not
// normalized. quant/dequant absorb those scaling factors.
// in this function, we just do (quant->unquant) and want the output to be
// comparable to the input. so unquant is the direct inverse of quant,
// and uses the dct scaling factors, not the idct ones.
static ALWAYS_INLINE
int quant_trellis_cabac( x264_t *h, dctcoef *dct,
const udctcoef *quant_mf, const int *unquant_mf,
const uint16_t *coef_weight, const uint8_t *zigzag,
int ctx_block_cat, int i_lambda2, int b_ac,
int b_chroma, int dc, int i_coefs, int idx )
{
udctcoef abs_coefs[64];
int8_t signs[64];
trellis_node_t nodes[2][8];
trellis_node_t *nodes_cur = nodes[0];
trellis_node_t *nodes_prev = nodes[1];
trellis_node_t *bnode;
const int b_interlaced = MB_INTERLACED;
uint8_t *cabac_state_sig = &h->cabac.state[ significant_coeff_flag_offset[b_interlaced][ctx_block_cat] ];
uint8_t *cabac_state_last = &h->cabac.state[ last_coeff_flag_offset[b_interlaced][ctx_block_cat] ];
const uint8_t *levelgt1_ctx = b_chroma && dc ? coeff_abs_levelgt1_ctx_chroma_dc : coeff_abs_levelgt1_ctx;
const int f = 1 << 15; // no deadzone
int i_last_nnz;
int i;
// (# of coefs) * (# of ctx) * (# of levels tried) = 1024
// we don't need to keep all of those: (# of coefs) * (# of ctx) would be enough,
// but it takes more time to remove dead states than you gain in reduced memory.
struct
{
uint16_t abs_level;
uint16_t next;
} level_tree[64*8*2];
int i_levels_used = 1;
/* init coefs */
for( i = i_coefs-1; i >= b_ac; i-- )
if( (unsigned)(dct[zigzag[i]] * (dc?quant_mf[0]>>1:quant_mf[zigzag[i]]) + f-1) >= 2*f )
break;
if( i < b_ac )
{
/* We only need to zero an empty 4x4 block. 8x8 can be
implicitly emptied via zero nnz, as can dc. */
if( i_coefs == 16 && !dc )
memset( dct, 0, 16 * sizeof(dctcoef) );
return 0;
}
i_last_nnz = i;
idx &= i_coefs == 64 ? 3 : 15;
for( ; i >= b_ac; i-- )
{
int coef = dct[zigzag[i]];
abs_coefs[i] = abs(coef);
signs[i] = coef>>31 | 1;
}
/* init trellis */
for( int j = 1; j < 8; j++ )
nodes_cur[j].score = TRELLIS_SCORE_MAX;
nodes_cur[0].score = 0;
nodes_cur[0].level_idx = 0;
level_tree[0].abs_level = 0;
level_tree[0].next = 0;
// coefs are processed in reverse order, because that's how the abs value is coded.
// last_coef and significant_coef flags are normally coded in forward order, but
// we have to reverse them to match the levels.
// in 4x4 blocks, last_coef and significant_coef use a separate context for each
// position, so the order doesn't matter, and we don't even have to update their contexts.
// in 8x8 blocks, some positions share contexts, so we'll just have to hope that
// cabac isn't too sensitive.
memcpy( nodes_cur[0].cabac_state, &h->cabac.state[ coeff_abs_level_m1_offset[ctx_block_cat] ], 10 );
for( i = i_last_nnz; i >= b_ac; i-- )
{
int i_coef = abs_coefs[i];
int q = ( f + i_coef * (dc?quant_mf[0]>>1:quant_mf[zigzag[i]]) ) >> 16;
int cost_sig[2], cost_last[2];
trellis_node_t n;
// skip 0s: this doesn't affect the output, but saves some unnecessary computation.
if( q == 0 )
{
// no need to calculate ssd of 0s: it's the same in all nodes.
// no need to modify level_tree for ctx=0: it starts with an infinite loop of 0s.
int sigindex = !dc && i_coefs == 64 ? significant_coeff_flag_offset_8x8[b_interlaced][i] :
b_chroma && dc && i_coefs == 8 ? coeff_flag_offset_chroma_422_dc[i] : i;
const uint32_t cost_sig0 = x264_cabac_size_decision_noup2( &cabac_state_sig[sigindex], 0 )
* (uint64_t)i_lambda2 >> ( CABAC_SIZE_BITS - LAMBDA_BITS );
for( int j = 1; j < 8; j++ )
{
if( nodes_cur[j].score != TRELLIS_SCORE_MAX )
{
#define SET_LEVEL(n,l) \
level_tree[i_levels_used].abs_level = l; \
level_tree[i_levels_used].next = n.level_idx; \
n.level_idx = i_levels_used; \
i_levels_used++;
SET_LEVEL( nodes_cur[j], 0 );
nodes_cur[j].score += cost_sig0;
}
}
continue;
}
XCHG( trellis_node_t*, nodes_cur, nodes_prev );
for( int j = 0; j < 8; j++ )
nodes_cur[j].score = TRELLIS_SCORE_MAX;
if( i < i_coefs-1 )
{
int sigindex = !dc && i_coefs == 64 ? significant_coeff_flag_offset_8x8[b_interlaced][i] :
b_chroma && dc && i_coefs == 8 ? coeff_flag_offset_chroma_422_dc[i] : i;
int lastindex = !dc && i_coefs == 64 ? last_coeff_flag_offset_8x8[i] :
b_chroma && dc && i_coefs == 8 ? coeff_flag_offset_chroma_422_dc[i] : i;
cost_sig[0] = x264_cabac_size_decision_noup2( &cabac_state_sig[sigindex], 0 );
cost_sig[1] = x264_cabac_size_decision_noup2( &cabac_state_sig[sigindex], 1 );
cost_last[0] = x264_cabac_size_decision_noup2( &cabac_state_last[lastindex], 0 );
cost_last[1] = x264_cabac_size_decision_noup2( &cabac_state_last[lastindex], 1 );
}
else
{
cost_sig[0] = cost_sig[1] = 0;
cost_last[0] = cost_last[1] = 0;
}
// there are a few cases where increasing the coeff magnitude helps,
// but it's only around .003 dB, and skipping them ~doubles the speed of trellis.
// could also try q-2: that sometimes helps, but also sometimes decimates blocks
// that are better left coded, especially at QP > 40.
for( int abs_level = q; abs_level >= q-1; abs_level-- )
{
int unquant_abs_level = (((dc?unquant_mf[0]<<1:unquant_mf[zigzag[i]]) * abs_level + 128) >> 8);
int d = i_coef - unquant_abs_level;
int64_t ssd;
/* Psy trellis: bias in favor of higher AC coefficients in the reconstructed frame. */
if( h->mb.i_psy_trellis && i && !dc && !b_chroma )
{
int orig_coef = (i_coefs == 64) ? h->mb.pic.fenc_dct8[idx][zigzag[i]] : h->mb.pic.fenc_dct4[idx][zigzag[i]];
int predicted_coef = orig_coef - i_coef * signs[i];
int psy_value = h->mb.i_psy_trellis * abs(predicted_coef + unquant_abs_level * signs[i]);
int psy_weight = (i_coefs == 64) ? x264_dct8_weight_tab[zigzag[i]] : x264_dct4_weight_tab[zigzag[i]];
ssd = (int64_t)d*d * coef_weight[i] - psy_weight * psy_value;
}
else
/* FIXME: for i16x16 dc is this weight optimal? */
ssd = (int64_t)d*d * (dc?256:coef_weight[i]);
for( int j = 0; j < 8; j++ )
{
int node_ctx = j;
if( nodes_prev[j].score == TRELLIS_SCORE_MAX )
continue;
n = nodes_prev[j];
/* code the proposed level, and count how much entropy it would take */
if( abs_level || node_ctx )
{
unsigned f8_bits = cost_sig[ abs_level != 0 ];
if( abs_level )
{
const int i_prefix = X264_MIN( abs_level - 1, 14 );
f8_bits += cost_last[ node_ctx == 0 ];
f8_bits += x264_cabac_size_decision2( &n.cabac_state[coeff_abs_level1_ctx[node_ctx]], i_prefix > 0 );
if( i_prefix > 0 )
{
uint8_t *ctx = &n.cabac_state[levelgt1_ctx[node_ctx]];
f8_bits += cabac_size_unary[i_prefix][*ctx];
*ctx = cabac_transition_unary[i_prefix][*ctx];
if( abs_level >= 15 )
f8_bits += bs_size_ue_big( abs_level - 15 ) << CABAC_SIZE_BITS;
node_ctx = coeff_abs_level_transition[1][node_ctx];
}
else
{
f8_bits += 1 << CABAC_SIZE_BITS;
node_ctx = coeff_abs_level_transition[0][node_ctx];
}
}
n.score += (uint64_t)f8_bits * i_lambda2 >> ( CABAC_SIZE_BITS - LAMBDA_BITS );
}
if( j || i || dc )
n.score += ssd;
/* Optimize rounding for DC coefficients in DC-only luma 4x4/8x8 blocks. */
else
{
d = i_coef * signs[0] - ((unquant_abs_level * signs[0] + 8)&~15);
n.score += (int64_t)d*d * coef_weight[i];
}
/* save the node if it's better than any existing node with the same cabac ctx */
if( n.score < nodes_cur[node_ctx].score )
{
SET_LEVEL( n, abs_level );
nodes_cur[node_ctx] = n;
}
}
}
}
/* output levels from the best path through the trellis */
bnode = &nodes_cur[0];
for( int j = 1; j < 8; j++ )
if( nodes_cur[j].score < bnode->score )
bnode = &nodes_cur[j];
if( bnode == &nodes_cur[0] )
{
if( i_coefs == 16 && !dc )
memset( dct, 0, 16 * sizeof(dctcoef) );
return 0;
}
int level = bnode->level_idx;
for( i = b_ac; level; i++ )
{
dct[zigzag[i]] = level_tree[level].abs_level * signs[i];
level = level_tree[level].next;
}
for( ; i < i_coefs; i++ )
dct[zigzag[i]] = 0;
return 1;
}
/* FIXME: This is a gigantic hack. See below.
*
* CAVLC is much more difficult to trellis than CABAC.
*
* CABAC has only three states to track: significance map, last, and the
* level state machine.
* CAVLC, by comparison, has five: coeff_token (trailing + total),
* total_zeroes, zero_run, and the level state machine.
*
* I know of no paper that has managed to design a close-to-optimal trellis
* that covers all five of these and isn't exponential-time. As a result, this
* "trellis" isn't: it's just a QNS search. Patches welcome for something better.
* It's actually surprisingly fast, albeit not quite optimal. It's pretty close
* though; since CAVLC only has 2^16 possible rounding modes (assuming only two
* roundings as options), a bruteforce search is feasible. Testing shows
* that this QNS is reasonably close to optimal in terms of compression.
*
* TODO:
* Don't bother changing large coefficients when it wouldn't affect bit cost
* (e.g. only affecting bypassed suffix bits).
* Don't re-run all parts of CAVLC bit cost calculation when not necessary.
* e.g. when changing a coefficient from one non-zero value to another in
* such a way that trailing ones and suffix length isn't affected. */
static ALWAYS_INLINE
int quant_trellis_cavlc( x264_t *h, dctcoef *dct,
const udctcoef *quant_mf, const int *unquant_mf,
const uint16_t *coef_weight, const uint8_t *zigzag,
int ctx_block_cat, int i_lambda2, int b_ac,
int b_chroma, int dc, int i_coefs, int idx, int b_8x8 )
{
ALIGNED_16( dctcoef quant_coefs[2][16] );
ALIGNED_16( dctcoef coefs[16] ) = {0};
int delta_distortion[16];
int64_t score = 1ULL<<62;
int i, j;
const int f = 1<<15;
int nC = b_chroma && dc ? 3 + (i_coefs>>2)
: ct_index[x264_mb_predict_non_zero_code( h, !b_chroma && dc ? (idx - LUMA_DC)*16 : idx )];
/* Code for handling 8x8dct -> 4x4dct CAVLC munging. Input/output use a different
* step/start/end than internal processing. */
int step = 1;
int start = b_ac;
int end = i_coefs - 1;
if( b_8x8 )
{
start = idx&3;
end = 60 + start;
step = 4;
}
idx &= 15;
i_lambda2 <<= LAMBDA_BITS;
/* Find last non-zero coefficient. */
for( i = end; i >= start; i -= step )
if( (unsigned)(dct[zigzag[i]] * (dc?quant_mf[0]>>1:quant_mf[zigzag[i]]) + f-1) >= 2*f )
break;
if( i < start )
goto zeroblock;
/* Prepare for QNS search: calculate distortion caused by each DCT coefficient
* rounding to be searched.
*
* We only search two roundings (nearest and nearest-1) like in CABAC trellis,
* so we just store the difference in distortion between them. */
int i_last_nnz = b_8x8 ? i >> 2 : i;
int coef_mask = 0;
int round_mask = 0;
for( i = b_ac, j = start; i <= i_last_nnz; i++, j += step )
{
int coef = dct[zigzag[j]];
int abs_coef = abs(coef);
int sign = coef < 0 ? -1 : 1;
int nearest_quant = ( f + abs_coef * (dc?quant_mf[0]>>1:quant_mf[zigzag[j]]) ) >> 16;
quant_coefs[1][i] = quant_coefs[0][i] = sign * nearest_quant;
coefs[i] = quant_coefs[1][i];
if( nearest_quant )
{
/* We initialize the trellis with a deadzone halfway between nearest rounding
* and always-round-down. This gives much better results than initializing to either
* extreme.
* FIXME: should we initialize to the deadzones used by deadzone quant? */
int deadzone_quant = ( f/2 + abs_coef * (dc?quant_mf[0]>>1:quant_mf[zigzag[j]]) ) >> 16;
int unquant1 = (((dc?unquant_mf[0]<<1:unquant_mf[zigzag[j]]) * (nearest_quant-0) + 128) >> 8);
int unquant0 = (((dc?unquant_mf[0]<<1:unquant_mf[zigzag[j]]) * (nearest_quant-1) + 128) >> 8);
int d1 = abs_coef - unquant1;
int d0 = abs_coef - unquant0;
delta_distortion[i] = (d0*d0 - d1*d1) * (dc?256:coef_weight[j]);
/* Psy trellis: bias in favor of higher AC coefficients in the reconstructed frame. */
if( h->mb.i_psy_trellis && j && !dc && !b_chroma )
{
int orig_coef = b_8x8 ? h->mb.pic.fenc_dct8[idx>>2][zigzag[j]] : h->mb.pic.fenc_dct4[idx][zigzag[j]];
int predicted_coef = orig_coef - coef;
int psy_weight = b_8x8 ? x264_dct8_weight_tab[zigzag[j]] : x264_dct4_weight_tab[zigzag[j]];
int psy_value0 = h->mb.i_psy_trellis * abs(predicted_coef + unquant0 * sign);
int psy_value1 = h->mb.i_psy_trellis * abs(predicted_coef + unquant1 * sign);
delta_distortion[i] += (psy_value0 - psy_value1) * psy_weight;
}
quant_coefs[0][i] = sign * (nearest_quant-1);
if( deadzone_quant != nearest_quant )
coefs[i] = quant_coefs[0][i];
else
round_mask |= 1 << i;
}
else
delta_distortion[i] = 0;
coef_mask |= (!!coefs[i]) << i;
}
/* Calculate the cost of the starting state. */
h->out.bs.i_bits_encoded = 0;
if( !coef_mask )
bs_write_vlc( &h->out.bs, x264_coeff0_token[nC] );
else
x264_cavlc_block_residual_internal( h, ctx_block_cat, coefs + b_ac, nC );
score = (int64_t)h->out.bs.i_bits_encoded * i_lambda2;
/* QNS loop: pick the change that improves RD the most, apply it, repeat.
* coef_mask and round_mask are used to simplify tracking of nonzeroness
* and rounding modes chosen. */
while( 1 )
{
int64_t iter_score = score;
int iter_distortion_delta = 0;
int iter_coef = -1;
int iter_mask = coef_mask;
int iter_round = round_mask;
for( i = b_ac; i <= i_last_nnz; i++ )
{
if( !delta_distortion[i] )
continue;
/* Set up all the variables for this iteration. */
int cur_round = round_mask ^ (1 << i);
int round_change = (cur_round >> i)&1;
int old_coef = coefs[i];
int new_coef = quant_coefs[round_change][i];
int cur_mask = (coef_mask&~(1 << i))|(!!new_coef << i);
int cur_distortion_delta = delta_distortion[i] * (round_change ? -1 : 1);
int64_t cur_score = cur_distortion_delta;
coefs[i] = new_coef;
/* Count up bits. */
h->out.bs.i_bits_encoded = 0;
if( !cur_mask )
bs_write_vlc( &h->out.bs, x264_coeff0_token[nC] );
else
x264_cavlc_block_residual_internal( h, ctx_block_cat, coefs + b_ac, nC );
cur_score += (int64_t)h->out.bs.i_bits_encoded * i_lambda2;
coefs[i] = old_coef;
if( cur_score < iter_score )
{
iter_score = cur_score;
iter_coef = i;
iter_mask = cur_mask;
iter_round = cur_round;
iter_distortion_delta = cur_distortion_delta;
}
}
if( iter_coef >= 0 )
{
score = iter_score - iter_distortion_delta;
coef_mask = iter_mask;
round_mask = iter_round;
coefs[iter_coef] = quant_coefs[((round_mask >> iter_coef)&1)][iter_coef];
/* Don't try adjusting coefficients we've already adjusted.
* Testing suggests this doesn't hurt results -- and sometimes actually helps. */
delta_distortion[iter_coef] = 0;
}
else
break;
}
if( coef_mask )
{
for( i = b_ac, j = start; i <= i_last_nnz; i++, j += step )
dct[zigzag[j]] = coefs[i];
for( ; j <= end; j += step )
dct[zigzag[j]] = 0;
return 1;
}
zeroblock:
if( !dc )
{
if( b_8x8 )
for( i = start; i <= end; i+=step )
dct[zigzag[i]] = 0;
else
memset( dct, 0, 16*sizeof(dctcoef) );
}
return 0;
}
int x264_quant_luma_dc_trellis( x264_t *h, dctcoef *dct, int i_quant_cat, int i_qp, int ctx_block_cat, int b_intra, int idx )
{
if( h->param.b_cabac )
return quant_trellis_cabac( h, dct,
h->quant4_mf[i_quant_cat][i_qp], h->unquant4_mf[i_quant_cat][i_qp], NULL, x264_zigzag_scan4[MB_INTERLACED],
ctx_block_cat, h->mb.i_trellis_lambda2[0][b_intra], 0, 0, 1, 16, idx );
return quant_trellis_cavlc( h, dct,
h->quant4_mf[i_quant_cat][i_qp], h->unquant4_mf[i_quant_cat][i_qp], NULL, x264_zigzag_scan4[MB_INTERLACED],
DCT_LUMA_DC, h->mb.i_trellis_lambda2[0][b_intra], 0, 0, 1, 16, idx, 0 );
}
static const uint8_t x264_zigzag_scan2x2[4] = { 0, 1, 2, 3 };
static const uint8_t x264_zigzag_scan2x4[8] = { 0, 2, 1, 4, 6, 3, 5, 7 };
int x264_quant_chroma_dc_trellis( x264_t *h, dctcoef *dct, int i_qp, int b_intra, int idx )
{
const uint8_t *zigzag;
int num_coefs;
int quant_cat = CQM_4IC+1 - b_intra;
if( CHROMA_FORMAT == CHROMA_422 )
{
zigzag = x264_zigzag_scan2x4;
num_coefs = 8;
}
else
{
zigzag = x264_zigzag_scan2x2;
num_coefs = 4;
}
if( h->param.b_cabac )
return quant_trellis_cabac( h, dct,
h->quant4_mf[quant_cat][i_qp], h->unquant4_mf[quant_cat][i_qp], NULL, zigzag,
DCT_CHROMA_DC, h->mb.i_trellis_lambda2[1][b_intra], 0, 1, 1, num_coefs, idx );
return quant_trellis_cavlc( h, dct,
h->quant4_mf[quant_cat][i_qp], h->unquant4_mf[quant_cat][i_qp], NULL, zigzag,
DCT_CHROMA_DC, h->mb.i_trellis_lambda2[1][b_intra], 0, 1, 1, num_coefs, idx, 0 );
}
int x264_quant_4x4_trellis( x264_t *h, dctcoef *dct, int i_quant_cat,
int i_qp, int ctx_block_cat, int b_intra, int b_chroma, int idx )
{
static const uint8_t ctx_ac[14] = {0,1,0,0,1,0,0,1,0,0,0,1,0,0};
int b_ac = ctx_ac[ctx_block_cat];
if( h->param.b_cabac )
return quant_trellis_cabac( h, dct,
h->quant4_mf[i_quant_cat][i_qp], h->unquant4_mf[i_quant_cat][i_qp],
x264_dct4_weight2_zigzag[MB_INTERLACED],
x264_zigzag_scan4[MB_INTERLACED],
ctx_block_cat, h->mb.i_trellis_lambda2[b_chroma][b_intra], b_ac, b_chroma, 0, 16, idx );
return quant_trellis_cavlc( h, dct,
h->quant4_mf[i_quant_cat][i_qp], h->unquant4_mf[i_quant_cat][i_qp],
x264_dct4_weight2_zigzag[MB_INTERLACED],
x264_zigzag_scan4[MB_INTERLACED],
ctx_block_cat, h->mb.i_trellis_lambda2[b_chroma][b_intra], b_ac, b_chroma, 0, 16, idx, 0 );
}
int x264_quant_8x8_trellis( x264_t *h, dctcoef *dct, int i_quant_cat,
int i_qp, int ctx_block_cat, int b_intra, int b_chroma, int idx )
{
if( h->param.b_cabac )
{
return quant_trellis_cabac( h, dct,
h->quant8_mf[i_quant_cat][i_qp], h->unquant8_mf[i_quant_cat][i_qp],
x264_dct8_weight2_zigzag[MB_INTERLACED],
x264_zigzag_scan8[MB_INTERLACED],
ctx_block_cat, h->mb.i_trellis_lambda2[b_chroma][b_intra], 0, b_chroma, 0, 64, idx );
}
/* 8x8 CAVLC is split into 4 4x4 blocks */
int nzaccum = 0;
for( int i = 0; i < 4; i++ )
{
int nz = quant_trellis_cavlc( h, dct,
h->quant8_mf[i_quant_cat][i_qp], h->unquant8_mf[i_quant_cat][i_qp],
x264_dct8_weight2_zigzag[MB_INTERLACED],
x264_zigzag_scan8[MB_INTERLACED],
DCT_LUMA_4x4, h->mb.i_trellis_lambda2[b_chroma][b_intra], 0, b_chroma, 0, 16, idx*4+i, 1 );
/* Set up nonzero count for future calls */
h->mb.cache.non_zero_count[x264_scan8[idx*4+i]] = nz;
nzaccum |= nz;
}
return nzaccum;
}