ratectl.c
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上传日期:2013-02-17
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文件大小:13k
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Windows Mobile
开发平台:
C/C++
- /* ratectl.c, bitrate control routines (linear quantization only currently) */
- /* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */
- /*
- * Disclaimer of Warranty
- *
- * These software programs are available to the user without any license fee or
- * royalty on an "as is" basis. The MPEG Software Simulation Group disclaims
- * any and all warranties, whether express, implied, or statuary, including any
- * implied warranties or merchantability or of fitness for a particular
- * purpose. In no event shall the copyright-holder be liable for any
- * incidental, punitive, or consequential damages of any kind whatsoever
- * arising from the use of these programs.
- *
- * This disclaimer of warranty extends to the user of these programs and user's
- * customers, employees, agents, transferees, successors, and assigns.
- *
- * The MPEG Software Simulation Group does not represent or warrant that the
- * programs furnished hereunder are free of infringement of any third-party
- * patents.
- *
- * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
- * are subject to royalty fees to patent holders. Many of these patents are
- * general enough such that they are unavoidable regardless of implementation
- * design.
- *
- */
- #include <stdio.h>
- #include <math.h>
- #include "config.h"
- #include "global.h"
- /* private prototypes */
- static void calc_actj _ANSI_ARGS_((unsigned char *frame));
- static double var_sblk _ANSI_ARGS_((unsigned char *p, int lx));
- /* rate control variables */
- int Xi, Xp, Xb, r, d0i, d0p, d0b;
- double avg_act;
- static int R, T, d;
- static double actsum;
- static int Np, Nb, S, Q;
- static int prev_mquant;
- void rc_init_seq()
- {
- /* reaction parameter (constant) */
- if (r==0) r = (int)floor(2.0*bit_rate/frame_rate + 0.5);
- /* average activity */
- if (avg_act==0.0) avg_act = 400.0;
- /* remaining # of bits in GOP */
- R = 0;
- /* global complexity measure */
- if (Xi==0) Xi = (int)floor(160.0*bit_rate/115.0 + 0.5);
- if (Xp==0) Xp = (int)floor( 60.0*bit_rate/115.0 + 0.5);
- if (Xb==0) Xb = (int)floor( 42.0*bit_rate/115.0 + 0.5);
- /* virtual buffer fullness */
- if (d0i==0) d0i = (int)floor(10.0*r/31.0 + 0.5);
- if (d0p==0) d0p = (int)floor(10.0*r/31.0 + 0.5);
- if (d0b==0) d0b = (int)floor(1.4*10.0*r/31.0 + 0.5);
- /*
- if (d0i==0) d0i = (int)floor(10.0*r/(qscale_tab[0] ? 56.0 : 31.0) + 0.5);
- if (d0p==0) d0p = (int)floor(10.0*r/(qscale_tab[1] ? 56.0 : 31.0) + 0.5);
- if (d0b==0) d0b = (int)floor(1.4*10.0*r/(qscale_tab[2] ? 56.0 : 31.0) + 0.5);
- */
- fprintf(statfile,"nrate control: sequence initializationn");
- fprintf(statfile,
- " initial global complexity measures (I,P,B): Xi=%d, Xp=%d, Xb=%dn",
- Xi, Xp, Xb);
- fprintf(statfile," reaction parameter: r=%dn", r);
- fprintf(statfile,
- " initial virtual buffer fullness (I,P,B): d0i=%d, d0p=%d, d0b=%dn",
- d0i, d0p, d0b);
- fprintf(statfile," initial average activity: avg_act=%.1fn", avg_act);
- }
- void rc_init_GOP(np,nb)
- int np,nb;
- {
- R += (int) floor((1 + np + nb) * bit_rate / frame_rate + 0.5);
- Np = fieldpic ? 2*np+1 : np;
- Nb = fieldpic ? 2*nb : nb;
- fprintf(statfile,"nrate control: new group of pictures (GOP)n");
- fprintf(statfile," target number of bits for GOP: R=%dn",R);
- fprintf(statfile," number of P pictures in GOP: Np=%dn",Np);
- fprintf(statfile," number of B pictures in GOP: Nb=%dn",Nb);
- }
- /* Note: we need to substitute K for the 1.4 and 1.0 constants -- this can
- be modified to fit image content */
- /* Step 1: compute target bits for current picture being coded */
- void rc_init_pict(frame)
- unsigned char *frame;
- {
- double Tmin;
- switch (pict_type)
- {
- case I_TYPE:
- T = (int) floor(R/(1.0+Np*Xp/(Xi*1.0)+Nb*Xb/(Xi*1.4)) + 0.5);
- d = d0i;
- break;
- case P_TYPE:
- T = (int) floor(R/(Np+Nb*1.0*Xb/(1.4*Xp)) + 0.5);
- d = d0p;
- break;
- case B_TYPE:
- T = (int) floor(R/(Nb+Np*1.4*Xp/(1.0*Xb)) + 0.5);
- d = d0b;
- break;
- }
- Tmin = (int) floor(bit_rate/(8.0*frame_rate) + 0.5);
- if (T<Tmin)
- T = Tmin;
- S = bitcount();
- Q = 0;
- calc_actj(frame);
- actsum = 0.0;
- fprintf(statfile,"nrate control: start of picturen");
- fprintf(statfile," target number of bits: T=%dn",T);
- }
- static void calc_actj(frame)
- unsigned char *frame;
- {
- int i,j,k;
- unsigned char *p;
- double actj,var;
- k = 0;
- for (j=0; j<height2; j+=16)
- for (i=0; i<width; i+=16)
- {
- p = frame + ((pict_struct==BOTTOM_FIELD)?width:0) + i + width2*j;
- /* take minimum spatial activity measure of luminance blocks */
- actj = var_sblk(p,width2);
- var = var_sblk(p+8,width2);
- if (var<actj) actj = var;
- var = var_sblk(p+8*width2,width2);
- if (var<actj) actj = var;
- var = var_sblk(p+8*width2+8,width2);
- if (var<actj) actj = var;
- if (!fieldpic && !prog_seq)
- {
- /* field */
- var = var_sblk(p,width<<1);
- if (var<actj) actj = var;
- var = var_sblk(p+8,width<<1);
- if (var<actj) actj = var;
- var = var_sblk(p+width,width<<1);
- if (var<actj) actj = var;
- var = var_sblk(p+width+8,width<<1);
- if (var<actj) actj = var;
- }
- actj+= 1.0;
- mbinfo[k++].act = actj;
- }
- }
- void rc_update_pict()
- {
- double X;
- S = bitcount() - S; /* total # of bits in picture */
- R-= S; /* remaining # of bits in GOP */
- X = (int) floor(S*((0.5*(double)Q)/(mb_width*mb_height2)) + 0.5);
- d+= S - T;
- avg_act = actsum/(mb_width*mb_height2);
- switch (pict_type)
- {
- case I_TYPE:
- Xi = X;
- d0i = d;
- break;
- case P_TYPE:
- Xp = X;
- d0p = d;
- Np--;
- break;
- case B_TYPE:
- Xb = X;
- d0b = d;
- Nb--;
- break;
- }
- fprintf(statfile,"nrate control: end of picturen");
- fprintf(statfile," actual number of bits: S=%dn",S);
- fprintf(statfile," average quantization parameter Q=%.1fn",
- (double)Q/(mb_width*mb_height2));
- fprintf(statfile," remaining number of bits in GOP: R=%dn",R);
- fprintf(statfile,
- " global complexity measures (I,P,B): Xi=%d, Xp=%d, Xb=%dn",
- Xi, Xp, Xb);
- fprintf(statfile,
- " virtual buffer fullness (I,P,B): d0i=%d, d0p=%d, d0b=%dn",
- d0i, d0p, d0b);
- fprintf(statfile," remaining number of P pictures in GOP: Np=%dn",Np);
- fprintf(statfile," remaining number of B pictures in GOP: Nb=%dn",Nb);
- fprintf(statfile," average activity: avg_act=%.1fn", avg_act);
- }
- /* compute initial quantization stepsize (at the beginning of picture) */
- int rc_start_mb()
- {
- int mquant;
- if (q_scale_type)
- {
- mquant = (int) floor(2.0*d*31.0/r + 0.5);
- /* clip mquant to legal (linear) range */
- if (mquant<1)
- mquant = 1;
- if (mquant>112)
- mquant = 112;
- /* map to legal quantization level */
- mquant = non_linear_mquant_table[map_non_linear_mquant[mquant]];
- }
- else
- {
- mquant = (int) floor(d*31.0/r + 0.5);
- mquant <<= 1;
- /* clip mquant to legal (linear) range */
- if (mquant<2)
- mquant = 2;
- if (mquant>62)
- mquant = 62;
- prev_mquant = mquant;
- }
- /*
- fprintf(statfile,"rc_start_mb:n");
- fprintf(statfile,"mquant=%dn",mquant);
- */
- return mquant;
- }
- /* Step 2: measure virtual buffer - estimated buffer discrepancy */
- int rc_calc_mquant(j)
- int j;
- {
- int mquant;
- double dj, Qj, actj, N_actj;
- /* measure virtual buffer discrepancy from uniform distribution model */
- dj = d + (bitcount()-S) - j*(T/(mb_width*mb_height2));
- /* scale against dynamic range of mquant and the bits/picture count */
- Qj = dj*31.0/r;
- /*Qj = dj*(q_scale_type ? 56.0 : 31.0)/r; */
- actj = mbinfo[j].act;
- actsum+= actj;
- /* compute normalized activity */
- N_actj = (2.0*actj+avg_act)/(actj+2.0*avg_act);
- if (q_scale_type)
- {
- /* modulate mquant with combined buffer and local activity measures */
- mquant = (int) floor(2.0*Qj*N_actj + 0.5);
- /* clip mquant to legal (linear) range */
- if (mquant<1)
- mquant = 1;
- if (mquant>112)
- mquant = 112;
- /* map to legal quantization level */
- mquant = non_linear_mquant_table[map_non_linear_mquant[mquant]];
- }
- else
- {
- /* modulate mquant with combined buffer and local activity measures */
- mquant = (int) floor(Qj*N_actj + 0.5);
- mquant <<= 1;
- /* clip mquant to legal (linear) range */
- if (mquant<2)
- mquant = 2;
- if (mquant>62)
- mquant = 62;
- /* ignore small changes in mquant */
- if (mquant>=8 && (mquant-prev_mquant)>=-4 && (mquant-prev_mquant)<=4)
- mquant = prev_mquant;
- prev_mquant = mquant;
- }
- Q+= mquant; /* for calculation of average mquant */
- /*
- fprintf(statfile,"rc_calc_mquant(%d): ",j);
- fprintf(statfile,"bitcount=%d, dj=%f, Qj=%f, actj=%f, N_actj=%f, mquant=%dn",
- bitcount(),dj,Qj,actj,N_actj,mquant);
- */
- return mquant;
- }
- /* compute variance of 8x8 block */
- static double var_sblk(p,lx)
- unsigned char *p;
- int lx;
- {
- int i, j;
- unsigned int v, s, s2;
- s = s2 = 0;
- for (j=0; j<8; j++)
- {
- for (i=0; i<8; i++)
- {
- v = *p++;
- s+= v;
- s2+= v*v;
- }
- p+= lx - 8;
- }
- return s2/64.0 - (s/64.0)*(s/64.0);
- }
- /* VBV calculations
- *
- * generates warnings if underflow or overflow occurs
- */
- /* vbv_end_of_picture
- *
- * - has to be called directly after writing picture_data()
- * - needed for accurate VBV buffer overflow calculation
- * - assumes there is no byte stuffing prior to the next start code
- */
- static int bitcnt_EOP;
- void vbv_end_of_picture()
- {
- bitcnt_EOP = bitcount();
- bitcnt_EOP = (bitcnt_EOP + 7) & ~7; /* account for bit stuffing */
- }
- /* calc_vbv_delay
- *
- * has to be called directly after writing the picture start code, the
- * reference point for vbv_delay
- */
- void calc_vbv_delay()
- {
- double picture_delay;
- static double next_ip_delay; /* due to frame reordering delay */
- static double decoding_time;
- /* number of 1/90000 s ticks until next picture is to be decoded */
- if (pict_type == B_TYPE)
- {
- if (prog_seq)
- {
- if (!repeatfirst)
- picture_delay = 90000.0/frame_rate; /* 1 frame */
- else
- {
- if (!topfirst)
- picture_delay = 90000.0*2.0/frame_rate; /* 2 frames */
- else
- picture_delay = 90000.0*3.0/frame_rate; /* 3 frames */
- }
- }
- else
- {
- /* interlaced */
- if (fieldpic)
- picture_delay = 90000.0/(2.0*frame_rate); /* 1 field */
- else
- {
- if (!repeatfirst)
- picture_delay = 90000.0*2.0/(2.0*frame_rate); /* 2 flds */
- else
- picture_delay = 90000.0*3.0/(2.0*frame_rate); /* 3 flds */
- }
- }
- }
- else
- {
- /* I or P picture */
- if (fieldpic)
- {
- if(topfirst==(pict_struct==TOP_FIELD))
- {
- /* first field */
- picture_delay = 90000.0/(2.0*frame_rate);
- }
- else
- {
- /* second field */
- /* take frame reordering delay into account */
- picture_delay = next_ip_delay - 90000.0/(2.0*frame_rate);
- }
- }
- else
- {
- /* frame picture */
- /* take frame reordering delay into account*/
- picture_delay = next_ip_delay;
- }
- if (!fieldpic || topfirst!=(pict_struct==TOP_FIELD))
- {
- /* frame picture or second field */
- if (prog_seq)
- {
- if (!repeatfirst)
- next_ip_delay = 90000.0/frame_rate;
- else
- {
- if (!topfirst)
- next_ip_delay = 90000.0*2.0/frame_rate;
- else
- next_ip_delay = 90000.0*3.0/frame_rate;
- }
- }
- else
- {
- if (fieldpic)
- next_ip_delay = 90000.0/(2.0*frame_rate);
- else
- {
- if (!repeatfirst)
- next_ip_delay = 90000.0*2.0/(2.0*frame_rate);
- else
- next_ip_delay = 90000.0*3.0/(2.0*frame_rate);
- }
- }
- }
- }
- if (decoding_time==0.0)
- {
- /* first call of calc_vbv_delay */
- /* we start with a 7/8 filled VBV buffer (12.5% back-off) */
- picture_delay = ((vbv_buffer_size*16384*7)/8)*90000.0/bit_rate;
- if (fieldpic)
- next_ip_delay = (int)(90000.0/frame_rate+0.5);
- }
- /* VBV checks */
- /* check for underflow (previous picture) */
- if (!low_delay && (decoding_time < bitcnt_EOP*90000.0/bit_rate))
- {
- /* picture not completely in buffer at intended decoding time */
- if (!quiet)
- fprintf(stderr,"vbv_delay underflow! (decoding_time=%.1f, t_EOP=%.1fn)",
- decoding_time, bitcnt_EOP*90000.0/bit_rate);
- }
- /* when to decode current frame */
- decoding_time += picture_delay;
- /* warning: bitcount() may overflow (e.g. after 9 min. at 8 Mbit/s */
- vbv_delay = (int)(decoding_time - bitcount()*90000.0/bit_rate);
- /* check for overflow (current picture) */
- if ((decoding_time - bitcnt_EOP*90000.0/bit_rate)
- > (vbv_buffer_size*16384)*90000.0/bit_rate)
- {
- if (!quiet)
- fprintf(stderr,"vbv_delay overflow!n");
- }
- fprintf(statfile,
- "nvbv_delay=%d (bitcount=%d, decoding_time=%.2f, bitcnt_EOP=%d)n",
- vbv_delay,bitcount(),decoding_time,bitcnt_EOP);
- if (vbv_delay<0)
- {
- if (!quiet)
- fprintf(stderr,"vbv_delay underflow: %dn",vbv_delay);
- vbv_delay = 0;
- }
- if (vbv_delay>65535)
- {
- if (!quiet)
- fprintf(stderr,"vbv_delay overflow: %dn",vbv_delay);
- vbv_delay = 65535;
- }
- }