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enquant.c
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enquant.c
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/********************************************************************
* *
* THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. *
* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
* *
* THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2009 *
* by the Xiph.Org Foundation http://www.xiph.org/ *
* *
********************************************************************
function:
last mod: $Id$
********************************************************************/
#include <stdlib.h>
#include <string.h>
#include "encint.h"
void oc_quant_params_pack(oggpack_buffer *_opb,const th_quant_info *_qinfo){
const th_quant_ranges *qranges;
const th_quant_base *base_mats[2*3*64];
int indices[2][3][64];
int nbase_mats;
int nbits;
int ci;
int qi;
int qri;
int qti;
int pli;
int qtj;
int plj;
int bmi;
int i;
i=_qinfo->loop_filter_limits[0];
for(qi=1;qi<64;qi++)i=OC_MAXI(i,_qinfo->loop_filter_limits[qi]);
nbits=OC_ILOG_32(i);
oggpackB_write(_opb,nbits,3);
for(qi=0;qi<64;qi++){
oggpackB_write(_opb,_qinfo->loop_filter_limits[qi],nbits);
}
/*580 bits for VP3.*/
i=1;
for(qi=0;qi<64;qi++)i=OC_MAXI(_qinfo->ac_scale[qi],i);
nbits=OC_ILOGNZ_32(i);
oggpackB_write(_opb,nbits-1,4);
for(qi=0;qi<64;qi++)oggpackB_write(_opb,_qinfo->ac_scale[qi],nbits);
/*516 bits for VP3.*/
i=1;
for(qi=0;qi<64;qi++)i=OC_MAXI(_qinfo->dc_scale[qi],i);
nbits=OC_ILOGNZ_32(i);
oggpackB_write(_opb,nbits-1,4);
for(qi=0;qi<64;qi++)oggpackB_write(_opb,_qinfo->dc_scale[qi],nbits);
/*Consolidate any duplicate base matrices.*/
nbase_mats=0;
for(qti=0;qti<2;qti++)for(pli=0;pli<3;pli++){
qranges=_qinfo->qi_ranges[qti]+pli;
for(qri=0;qri<=qranges->nranges;qri++){
for(bmi=0;;bmi++){
if(bmi>=nbase_mats){
base_mats[bmi]=qranges->base_matrices+qri;
indices[qti][pli][qri]=nbase_mats++;
break;
}
else if(memcmp(base_mats[bmi][0],qranges->base_matrices[qri],
sizeof(base_mats[bmi][0]))==0){
indices[qti][pli][qri]=bmi;
break;
}
}
}
}
/*Write out the list of unique base matrices.
1545 bits for VP3 matrices.*/
oggpackB_write(_opb,nbase_mats-1,9);
for(bmi=0;bmi<nbase_mats;bmi++){
for(ci=0;ci<64;ci++)oggpackB_write(_opb,base_mats[bmi][0][ci],8);
}
/*Now store quant ranges and their associated indices into the base matrix
list.
46 bits for VP3 matrices.*/
nbits=OC_ILOG_32(nbase_mats-1);
for(i=0;i<6;i++){
qti=i/3;
pli=i%3;
qranges=_qinfo->qi_ranges[qti]+pli;
if(i>0){
if(qti>0){
if(qranges->nranges==_qinfo->qi_ranges[qti-1][pli].nranges&&
memcmp(qranges->sizes,_qinfo->qi_ranges[qti-1][pli].sizes,
qranges->nranges*sizeof(qranges->sizes[0]))==0&&
memcmp(indices[qti][pli],indices[qti-1][pli],
(qranges->nranges+1)*sizeof(indices[qti][pli][0]))==0){
oggpackB_write(_opb,1,2);
continue;
}
}
qtj=(i-1)/3;
plj=(i-1)%3;
if(qranges->nranges==_qinfo->qi_ranges[qtj][plj].nranges&&
memcmp(qranges->sizes,_qinfo->qi_ranges[qtj][plj].sizes,
qranges->nranges*sizeof(qranges->sizes[0]))==0&&
memcmp(indices[qti][pli],indices[qtj][plj],
(qranges->nranges+1)*sizeof(indices[qti][pli][0]))==0){
oggpackB_write(_opb,0,1+(qti>0));
continue;
}
oggpackB_write(_opb,1,1);
}
oggpackB_write(_opb,indices[qti][pli][0],nbits);
for(qi=qri=0;qi<63;qri++){
oggpackB_write(_opb,qranges->sizes[qri]-1,OC_ILOG_32(62-qi));
qi+=qranges->sizes[qri];
oggpackB_write(_opb,indices[qti][pli][qri+1],nbits);
}
}
}
static void oc_iquant_init(oc_iquant *_this,ogg_uint16_t _d){
ogg_uint32_t t;
int l;
_d<<=1;
l=OC_ILOGNZ_32(_d)-1;
t=1+((ogg_uint32_t)1<<16+l)/_d;
_this->m=(ogg_int16_t)(t-0x10000);
_this->l=l;
}
/*See comments at oc_dequant_tables_init() for how the quantization tables'
storage should be initialized.*/
void oc_enquant_tables_init(ogg_uint16_t *_dequant[64][3][2],
oc_iquant *_enquant[64][3][2],const th_quant_info *_qinfo){
int qi;
int pli;
int qti;
/*Initialize the dequantization tables first.*/
oc_dequant_tables_init(_dequant,NULL,_qinfo);
/*Derive the quantization tables directly from the dequantization tables.*/
for(qi=0;qi<64;qi++)for(qti=0;qti<2;qti++)for(pli=0;pli<3;pli++){
int zzi;
int plj;
int qtj;
int dupe;
dupe=0;
for(qtj=0;qtj<=qti;qtj++){
for(plj=0;plj<(qtj<qti?3:pli);plj++){
if(_dequant[qi][pli][qti]==_dequant[qi][plj][qtj]){
dupe=1;
break;
}
}
if(dupe)break;
}
if(dupe){
_enquant[qi][pli][qti]=_enquant[qi][plj][qtj];
continue;
}
/*In the original VP3.2 code, the rounding offset and the size of the
dead zone around 0 were controlled by a "sharpness" parameter.
We now R-D optimize the tokens for each block after quantization,
so the rounding offset should always be 1/2, and an explicit dead
zone is unnecessary.
Hence, all of that VP3.2 code is gone from here, and the remaining
floating point code has been implemented as equivalent integer
code with exact precision.*/
for(zzi=0;zzi<64;zzi++){
oc_iquant_init(_enquant[qi][pli][qti]+zzi,
_dequant[qi][pli][qti][zzi]);
}
}
}
/*This table gives the square root of the fraction of the squared magnitude of
each DCT coefficient relative to the total, scaled by 2**16, for both INTRA
and INTER modes.
These values were measured after motion-compensated prediction, before
quantization, over a large set of test video (from QCIF to 1080p) encoded at
all possible rates.
The DC coefficient takes into account the DPCM prediction (using the
quantized values from neighboring blocks, as the encoder does, but still
before quantization of the coefficient in the current block).
The results differ significantly from the expected variance (e.g., using an
AR(1) model of the signal with rho=0.95, as is frequently done to compute
the coding gain of the DCT).
We use them to estimate an "average" quantizer for a given quantizer matrix,
as this is used to parameterize a number of the rate control decisions.
These values are themselves probably quantizer-matrix dependent, since the
shape of the matrix affects the noise distribution in the reference frames,
but they should at least give us _some_ amount of adaptivity to different
matrices, as opposed to hard-coding a table of average Q values for the
current set.
The main features they capture are that a) only a few of the quantizers in
the upper-left corner contribute anything significant at all (though INTER
mode is significantly flatter) and b) the DPCM prediction of the DC
coefficient gives a very minor improvement in the INTRA case and a quite
significant one in the INTER case (over the expected variance).*/
static const ogg_uint16_t OC_RPSD[2][64]={
{
52725,17370,10399, 6867, 5115, 3798, 2942, 2076,
17370, 9900, 6948, 4994, 3836, 2869, 2229, 1619,
10399, 6948, 5516, 4202, 3376, 2573, 2015, 1461,
6867, 4994, 4202, 3377, 2800, 2164, 1718, 1243,
5115, 3836, 3376, 2800, 2391, 1884, 1530, 1091,
3798, 2869, 2573, 2164, 1884, 1495, 1212, 873,
2942, 2229, 2015, 1718, 1530, 1212, 1001, 704,
2076, 1619, 1461, 1243, 1091, 873, 704, 474
},
{
23411,15604,13529,11601,10683, 8958, 7840, 6142,
15604,11901,10718, 9108, 8290, 6961, 6023, 4487,
13529,10718, 9961, 8527, 7945, 6689, 5742, 4333,
11601, 9108, 8527, 7414, 7084, 5923, 5175, 3743,
10683, 8290, 7945, 7084, 6771, 5754, 4793, 3504,
8958, 6961, 6689, 5923, 5754, 4679, 3936, 2989,
7840, 6023, 5742, 5175, 4793, 3936, 3522, 2558,
6142, 4487, 4333, 3743, 3504, 2989, 2558, 1829
}
};
/*The fraction of the squared magnitude of the residuals in each color channel
relative to the total, scaled by 2**16, for each pixel format.
These values were measured after motion-compensated prediction, before
quantization, over a large set of test video encoded at all possible rates.
TODO: These values are only from INTER frames; it should be re-measured for
INTRA frames.*/
static const ogg_uint16_t OC_PCD[4][3]={
{59926, 3038, 2572},
{55201, 5597, 4738},
{55201, 5597, 4738},
{47682, 9669, 8185}
};
/*Compute an "average" quantizer for each qi level.
We do one for INTER and one for INTRA, since their behavior is very
different, but average across chroma channels.
The basic approach is to compute a harmonic average of the squared quantizer,
weighted by the expected squared magnitude of the DCT coefficients.
Under the (not quite true) assumption that DCT coefficients are
Laplacian-distributed, this preserves the product Q*lambda, where
lambda=sqrt(2/sigma**2) is the Laplacian distribution parameter (not to be
confused with the lambda used in R-D optimization throughout most of the
rest of the code).
The value Q*lambda completely determines the entropy of the coefficients.*/
void oc_enquant_qavg_init(ogg_int64_t _log_qavg[2][64],
ogg_uint16_t *_dequant[64][3][2],int _pixel_fmt){
int qi;
int pli;
int qti;
int ci;
for(qti=0;qti<2;qti++)for(qi=0;qi<64;qi++){
ogg_int64_t q2;
q2=0;
for(pli=0;pli<3;pli++){
ogg_uint32_t qp;
qp=0;
for(ci=0;ci<64;ci++){
unsigned rq;
unsigned qd;
qd=_dequant[qi][pli][qti][OC_IZIG_ZAG[ci]];
rq=(OC_RPSD[qti][ci]+(qd>>1))/qd;
qp+=rq*(ogg_uint32_t)rq;
}
q2+=OC_PCD[_pixel_fmt][pli]*(ogg_int64_t)qp;
}
/*qavg=1.0/sqrt(q2).*/
_log_qavg[qti][qi]=OC_Q57(48)-oc_blog64(q2)>>1;
}
}