?? vop_code.c
字號:
//視頻對象平面編碼函數代碼
#include "vop_code.h"
#include "mot_est_comp.h"
//#include "rc_q2.h"
#include "bitstream.h"
#include "rate_ctl.h"
#define SCENE_CHANGE_THREADHOLD 50
#define MB_RATIO_THREADHOLD 0.40
extern FILE *ftrace;
UInt BitstreamPutVopHeader ( Vop *vop,
Float time,
VolConfig *vol_config
);
Void ImageRepetitivePadding(Image *image, Int edge);
Double compute_MAD(Vop *vop);
/***********************************************************CommentBegin******
函數功能：
實現視頻對象平面中對象形狀、紋理和運動的編碼。并且，前提假設輸入的視頻對象平面是帶邊界的。
函數輸入：
1）Vop* curr：指向當前待編碼的視頻對象平面的指針；
2）Vop* prev：指向本視頻對象平面之前最后出現的視頻對象平面的指針；
3）Vop* rec_prev：指向本視頻對象平面之前最后已出現并編碼的視頻對象平面的指針；
4）Int enable_8x8_mv：8×8運動向量的標志；
5）Int intra_dcpred_disable：不允許內部DC頻段預測的控制變量；
6）Float time：當前編碼時間；
7）VolConfig* vol_config：視頻對象層的設置信息。
函數輸入/輸出：
1）Vop* rec_curr：以編碼視頻對象平面；
2）Bitcount num_bits：比特統計結構。
***********************************************************CommentEnd********/
Void VopCode(Vop *curr, Vop *reference, Vop *reconstruct, Vop *error, Int enable_8x8_mv,
Float time, VolConfig *vol_config)
{
ImageF *mot_x=NULL, *mot_y=NULL;
Image *MB_decisions=NULL;
Int edge,f_code_for=1;
Vop *error_vop=NULL;
Int vop_quantizer;
Float mad_P = 0., mad_I = 0.;
Float IntraMBRatio = 1.;
Int numberMB, i, IntraMB;
edge = 0;
f_code_for = curr->fcode_for;
if (curr->prediction_type == P_VOP)
{
/*進行運動估計和補償*/
MotionEstimationCompensation(curr, reference,
enable_8x8_mv, edge ,f_code_for,
reconstruct, &mad_P, &mot_x,&mot_y,&MB_decisions);
/*計算處于幀內的宏塊所占的百分比*/
IntraMB = 0;
numberMB = MB_decisions->x * MB_decisions->y;
for (i = 0; i < numberMB; i ++)
if (MB_decisions->f[i] == MBM_INTRA) IntraMB ++;
IntraMBRatio = (float)IntraMB / (float)numberMB;
#ifdef _RC_
fprintf(ftrace, "ME with MAD : %f\n", mad_P);
fprintf(ftrace, "%4.2f of the MBs are I-MBs.\n", IntraMBRatio);
#endif
}
else
mad_P = SCENE_CHANGE_THREADHOLD * 2;
if ((mad_P < SCENE_CHANGE_THREADHOLD / 3) ||
((mad_P < SCENE_CHANGE_THREADHOLD) && (IntraMBRatio < MB_RATIO_THREADHOLD)))
{
//容忍值未超過，繼續進行P-VOP的編碼
curr->prediction_type = P_VOP;
error->prediction_type = P_VOP;
#ifdef _RC_
fprintf(ftrace, "Coding mode : INTER\n");
#endif
vop_quantizer = RateCtlGetQ(mad_P);
curr->quantizer = vop_quantizer;
error->quantizer = vop_quantizer;
#ifdef _RC_DEBUG_
fprintf(stdout, "RC: >>>>> New quantizer= %d\n", vop_quantizer);
#endif
SubImage(curr->y_chan, reconstruct->y_chan, error->y_chan);
SubImage(curr->u_chan, reconstruct->u_chan, error->u_chan);
SubImage(curr->v_chan, reconstruct->v_chan, error->v_chan);
BitstreamPutVopHeader(curr,time,vol_config);
VopShapeMotText(error, reconstruct, MB_decisions,
mot_x, mot_y, f_code_for,
GetVopIntraACDCPredDisable(curr), reference,
NULL/*運動紋理比特流數據*/);
} else {
//容忍值過大
//此時的編碼模式應轉為I-VOP模式
curr->prediction_type = I_VOP;
curr->rounding_type = 1;
#ifdef _RC_
fprintf(ftrace, "Coding mode : INTRA\n");
#endif
//上一次的容忍值是假設計算的，現在有必要重新計算容忍值
//內部編碼，可能實際的差分值不是編碼的大系數
if (mad_I == 0.) mad_I = (Float) compute_MAD(curr);
vop_quantizer = RateCtlGetQ(mad_I);
curr->intra_quantizer = vop_quantizer;
curr->rounding_type = 1;
BitstreamPutVopHeader(curr,time,vol_config);
/*以內部模式進行紋理編碼*/
VopCodeShapeTextIntraCom(curr,
reference,
NULL/*紋理編碼數據*/
);
}
if (MB_decisions) FreeImage(MB_decisions);
if (mot_x) FreeImage(mot_x);
if (mot_y) FreeImage(mot_y);
ImageRepetitivePadding(reference->y_chan, 16);
ImageRepetitivePadding(reference->u_chan, 8);
ImageRepetitivePadding(reference->v_chan, 8);
Bitstream_NextStartCode();
return;
}
/* CodeVop() */
/***********************************************************CommentBegin******
函數功能：
本函數將完成視頻對象平面頭部句法的寫入，它將頭部句法的所有信息寫到數據流磁盤文件中。
函數輸入：
Vop* vop：指向包含有頭部信息的視頻對象平面的指針。
函數返回值：
UInt num_bits：被寫入的比特位的個數。
函數描述：
視頻對象平面的頭部信息（起始編碼，視頻對象平面的ID等等）首先被寫入，寫入的格式是整形的比特流數據結構，然后再輸出到磁盤文件中。
***********************************************************CommentEnd********/
Uint BitstreamPutVopHeader(Vop *vop, Float time, VolConfig *vol_config)
{
Image *buffer = NULL;
Int bits;
Int time_modulo;
Float time_inc;
Int index;
UInt num_bits_header=0;
/*將視頻對象平面頭信息中的所有句法寫入在數據結構中*/
BitstreamPutBits(buffer,VOP_START_CODE,VOP_START_CODE_LENGTH);
BitstreamPutBits(buffer,GetVopPredictionType(vop),2);
index = GetVolConfigModTimeBase(vol_config, 1);
time_modulo = (int)time - index*1000;
while(time_modulo >= 1000)
{
BitstreamPutBits(buffer,1,1);
time_modulo = time_modulo - 1000;
index++;
printf("time modulo : 1\n");
}
BitstreamPutBits(buffer,0,1);
/*保存這種模時間基*/
PutVolConfigModTimeBase(index,vol_config);
time_inc = (time - index*1000);
bits = (int)ceil(log((double)GetVopTimeIncrementResolution(vop))/log(2.0));
if (bits<1) bits=1;
time_inc=time_inc*GetVopTimeIncrementResolution(vop)/1000.0f;
/*標志比特位*/
BitstreamPutBits(buffer,1,1);
BitstreamPutBits(buffer,(Int)(time_inc+0.001),bits);
/*標志比特位*/
BitstreamPutBits(buffer,1,1);
if (GetVopWidth(vop)==0)
{
printf("Empty VOP at %.2f\n",time);
BitstreamPutBits(buffer,0L,1L);
num_bits_header += Bitstream_NextStartCode();
return(num_bits_header);
}
else
BitstreamPutBits(buffer,1L,1L);
if( GetVopPredictionType(vop) == P_VOP )
BitstreamPutBits(buffer,GetVopRoundingType(vop),1);
BitstreamPutBits(buffer,GetVopIntraDCVlcThr(vop),3);
if (GetVopPredictionType(vop) == I_VOP) /* I_VOP */
BitstreamPutBits(buffer,GetVopIntraQuantizer(vop),GetVopQuantPrecision(vop));
else /* P_VOP */
BitstreamPutBits(buffer,GetVopQuantizer(vop),GetVopQuantPrecision(vop));
if (GetVopPredictionType(vop)!=I_VOP)
{
BitstreamPutBits(buffer,GetVopFCodeFor(vop),3);
}
return(num_bits_header);
}
// 完成圖像的重復填充，在填充過程中，保證在邊界設置上Y、U、V分別是16、4、4模式。
Void ImageRepetitivePadding(Image *image, Int edge)
{
SInt *p, left, right;
Int width, height, x, y;
p = image->f;
width = image->x;
height = image->y;
/* Horizontal Padding */
for( y=edge; y<height-edge; y++)
{
left = p[y*width+edge];
right = p[y*width+width-edge-1];
for(x=0; x<edge; x++)
{
p[y*width+x] = left;
p[y*width+width-edge+x] = right;
}
}
/* Vertical Padding */
for(y=0; y<edge; y++)
for(x=0; x<width; x++)
p[y*width+x] = p[edge*width+x];
for(y=height-edge; y<height; y++)
for(x=0; x<width; x++)
p[y*width+x] = p[(height-1-edge)*width+x];
return;
}
/***********************************************************CommentBegin******
函數功能：
本函數用于計算視頻對象平面的誤差容忍值。
函數輸入：
Vop* error_vop：存在殘留誤差的視頻對象平面。
函數描述：
本函數僅僅在編碼模式為I-VOP時才進行調用。
***********************************************************CommentEnd********/
Double compute_MAD(Vop *error_vop)
{
SInt *curr_in,
*curr_end;
Float *curr_fin,
*curr_fend;
UInt sxy_in;
Double mad=0.0, dc = 0.0;
Int cnt=0;
/*計算容忍值*/
switch (GetImageType(error_vop->y_chan))
{
case SHORT_TYPE:
/*計算AC頻段的容忍值*/
/* 首先要計算平均值*/
curr_in = (SInt*)GetImageData(error_vop->y_chan);
sxy_in = GetImageSize(error_vop->y_chan);
curr_end = curr_in + sxy_in;
cnt = 0;
while (curr_in != curr_end)
{
dc += *curr_in; //abs(*curr_in);
cnt++;
curr_in++;
}
dc /= cnt;
curr_in = (SInt*)GetImageData(error_vop->y_chan);
sxy_in = GetImageSize(error_vop->y_chan);
curr_end = curr_in + sxy_in;
cnt = 0;
while (curr_in != curr_end)
{
mad += fabs(*curr_in - dc);
cnt++;
curr_in++;
}
mad /= cnt;
break;
case FLOAT_TYPE:
curr_fin = (Float*)GetImageData(error_vop->y_chan);
sxy_in = GetImageSize(error_vop->y_chan);
curr_fend = curr_fin + sxy_in;
cnt = 0;
while (curr_fin != curr_fend)
{
mad += fabs(*curr_fin);
cnt++;
curr_fin++;
}
mad /= cnt;
break;
default: break;
}
#ifdef _RC_
fprintf(ftrace, "The MAD of the VOP to be coded is %f.\n", mad);
#endif
return mad;
}
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