#include "sim.h"#ifdef OFFLINE_RATE_CONTROL /* 離線碼率控制處理
該碼率控制函數適用于離線處理的應用，其目的是為了取得最優的率控制效果。
該函數會在以下條件的制約下受到影響：
1）幀率過高
2）量化器的起始步長過小
3）碼率控制起動過晚
4）視頻序列過短*/#include <stdio.h>#include <math.h>/********************************************************************** * *	Name:	        FrameUpdateQP *	Description:    updates quantizer once per frame for  *                      simplified rate control *	 *      Returns:        new quantizer *	Side effects: * *	Date: 950910	Author: Karl.Lillevold@nta.no * ***********************************************************************/int FrameUpdateQP(int buf, int bits, int frames_left, int QP, int B,           float seconds) {  int newQP, dQP;  float buf_rest, buf_rest_pic;  buf_rest = seconds * B - (float)buf;  newQP = QP;  if (frames_left > 0) {    buf_rest_pic = buf_rest / (float)frames_left;    printf("\n");    printf("  Simplified rate control for %d remaining pictures:\n",           frames_left);    printf("  Bits spent / left       : %8d / %d (%d per picture)\n",            buf, mnint(buf_rest), mnint(buf_rest_pic));    dQP = mmax(1,QP*0.1);    printf("  Limits                  : %8.0f / %.0f\n",            buf_rest_pic / 1.15, buf_rest_pic * 1.15);    printf("  Bits spent on last frame: %8d\n", bits);    if (bits > buf_rest_pic * 1.15) {      newQP = mmin(31,QP+dQP);      printf("  QP -> new QP            : %2d -> %2d\n", QP, newQP);    }    else if (bits < buf_rest_pic / 1.15) {      newQP = mmax(1,QP-dQP);      printf("  QP -> new QP            : %2d -> %2d\n", QP, newQP);    }    else {      printf("  QP not changed\n");    }  }  printf("\n");  return newQP;}#else/* MPEG－4中的實現*/#include <math.h>/* rate control static variables */static float B_prev;     /* number of bits spent for the previous frame */static float B_target;   /* target number of bits/picture               */static float global_adj; /* due to bits spent for the previous frame    */void InitializeRateControl(){  B_prev = (float)0.0;}void UpdateRateControl(int bits){  B_prev = (float)bits;}int InitializeQuantizer(int pict_type, float bit_rate,         float target_frame_rate, float QP_mean) /* QP_mean = mean quantizer parameter for the previous picture *//* bitcount = current total bit count                          *//* To calculate bitcount in coder.c, do something like this :  *//* int bitcount;                                               *//* AddBitsPicture(bits);                                       *//* bitcount = bits->total;                                     */{  int newQP;  if (pict_type == PCT_INTER) {    B_target = bit_rate / target_frame_rate;    /* compute picture buffer descrepency as of the previous picture */    if (B_prev != 0.0) {      global_adj = (B_prev - B_target) / (2*B_target);    }    else {      global_adj = (float)0.0;    }    newQP = (int)(QP_mean * (1 + global_adj) + (float)0.5);    newQP = mmax(1,mmin(31,newQP));    }  else if (pict_type == PCT_INTRA) {    fprintf(stderr,"No need to call InititializeQuantizer() for Intra picture\n");    exit(-1);  }  else  {    fprintf(stderr,"Error (InitializePictureRate): picture type unkown.\n");    exit(-1);  }  #if 1  printf("Global adj = %.2f\n", global_adj);  printf("meanQP = %.2f   newQP = %d\n", QP_mean, newQP);#endif  fprintf(stdout,"Target no. of bits: %.2f\n", B_target);  return newQP;}/**********************************************************************   Name:          UpdateQuantizer*** Description: This function generates a new quantizer step size based*                  on bits spent up until current macroblock and bits*                  spent from the previous picture.  Note: this*                  routine should be called at the beginning of each*                  macroblock line as specified by TMN4. However, this*                  can be done at any macroblock if so desired.**  Input: current macroblock number (raster scan), mean quantizer*  paramter for previous picture, bit rate, source frame rate,*  hor. number of macroblocks, vertical number of macroblocks, total #*  of bits used until now in the current picture.**  Returns: Returns a new quantizer step size for the use of current*  macroblock Note: adjustment to fit with 2-bit DQUANT should be done*  in the calling program.**  Side Effects:  **  Date: 1/5/95    Author: Anurag Bist***********************************************************************/int UpdateQuantizer(int mb, float QP_mean, int pict_type, float bit_rate,                     int mb_width, int mb_height, int bitcount) /* mb = macroblock index number *//* QP_mean = mean quantizer parameter for the previous picture *//* bitcount = total # of bits used until now in the current picture */{  int newQP=16;  float local_adj, descrepency, projection;    if (pict_type == PCT_INTRA) {    newQP = 16;  }  else if (pict_type == PCT_INTER) {    /* compute expected buffer fullness */        projection = mb * (B_target / (mb_width*mb_height));        /* measure descrepency between current fullness and projection */    descrepency= (bitcount - projection);        /* scale */        local_adj = 12 * descrepency / bit_rate;    #if 0    printf("mb = %d\n",mb);    printf("bit_count = %d projection = %.2f \n",bitcount,projection);    printf("B_target = %.2f local_adj = %.2f \n",B_target,local_adj);#endif        newQP = (int)(QP_mean * (1 + global_adj + local_adj) + 0.5);      /* the update equation for newQP in TMN4 document section 3.7 */  }  else  {    fprintf(stderr,"Error (UpdateQuantizer): picture type unkown.\n");  }  #if 0  printf("mb = %d  newQP = %d \n",mb,newQP);#endif   newQP = mmax(1,mmin(31,newQP));    return newQP;}#endif