Chap 4. MPEG-2 부호기 전체 구조와 알고리즘 컴퓨터정보통신공학과 S&S LAB 최면욱

Content 4.1 전체구조 4.2 MPEG-부호기 전체구조 4.3 main() 처리루틴 4.4 파라미터 설정화일 4.5 양자화 매트릭스 파일설정

4.1 전체구조

4.2 MPEG-2 부호기 전체구조

4.3 main() 처리루틴 int main(argc,argv) /* mpeg2enc.c */ int argc; char *argv[]; {   if (argc!=3)   {     printf("\n%s, %s\n",version,author);     printf("Usage: mpeg2encode in.par out.m2v\n");     exit(0);   }   readparmfile(argv[1]); /*1. read parameter file */   readquantmat();   /*2. read quantization matrices */   /* open output file */   if (!(outfile=fopen(argv[2],"wb")))     sprintf(errortext,"Couldn't create output file %s",argv[2]);     error(errortext);   init(); /* 3. 비트, fdct 및 idct의 초기화과정   putseq() ; /* 4. 총프레임에 따라 반복루틴을 수행하면서 하나의 픽처를 부호화 */   fclose(outfile);   fclose(statfile);   return 0; }

4.3 main() 처리루틴

4.4 파라미터 설정 파일 MPEG-2 Test Sequence, 25 frames/sec /* PAL.par */ test%d    /* name of source files */ q%d       /* name of reconstructed images ("-": don't store) */ -         /* name of intra quant matrix file     ("-": default matrix) */ -         /* name of non intra quant matrix file ("-": default matrix) */ stat.out  /* name of statistics file ("-": stdout ) */ 0         /* input picture file format: 0=*.Y,*.U,*.V, 1=*.yuv, 2=*.ppm */ 150       /* number of frames */ 0         /* number of first frame */ 00:00:00:00 /* timecode of first frame */ 12        /* N (# GOP안에 포함되는 프레임 수) */ 3         /* M (I/P frame 사이의 거리, 사이에 몇 개의 B프레임이 존재하는가 확인) */ 0         /* ISO/IEC 11172-2 stream 0이면 MPEG1처리 1이면 MPEG2처리*/ 0         /* 0:frame pictures, 1: field pictures */ 704       /* horizontal_size */ 576       /* vertical_size */ 2         /* aspect_ratio_information(종횡비 정보) 1=square pel, 2=4:3, 3=16:9, 4=2.11:1 */ 3         /* frame_rate_code 1=23.976, 2=24, 3=25, 4=29.97, 5=30 frames/sec. */ 5000000.0 /* bit_rate (bits/s) 비트율의 최대값 */ 112       /* vbv_buffer_size (in multiples of 16 kbit) 가상버퍼사이즈*/ 0         /* low_delay  1로 설정하면 B픽처가 없음 */ 0         /* constrained_parameters_flag */ 4         /* Profile ID: Simple = 5, Main = 4, SNR = 3, Spatial = 2, High = 1 */ 8         /* Level ID:   Low = 10, Main = 8, High 1440 = 6, High = 4          */ 0         /* progressive_sequence */ 1         /* chroma_format: 1=4:2:0, 2=4:2:2, 3=4:4:4 */ 1         /* video_format: 0=comp., 1=PAL, 2=NTSC, 3=SECAM, 4=MAC, 5=unspec. */ 5         /* color_primaries */

4.4 파라미터 설정 파일 5 /* transfer_characteristics */ 5         /* matrix_coefficients */ 704       /* display_horizontal_size */ 576       /* display_vertical_size */ 0         /* intra_dc_precision (0: 8 bit, 1: 9 bit, 2: 10 bit, 3: 11 bit */ 1         /* top_field_first */ 0 0 0     /* frame_pred_frame_dct (I P B) */ 0 0 0     /* concealment_motion_vectors (I P B) */ 1 1 1     /* q_scale_type  (I P B) */ 1 0 0     /* intra_vlc_format (I P B)*/ 0 0 0     /* alternate_scan (I P B) */ 0         /* repeat_first_field */ 0         /* progressive_frame */ 0         /* P distance between complete intra slice refresh */ 0         /* rate control: r (reaction parameter) */ 0         /* rate control: avg_act (initial average activity) */ 0         /* rate control: Xi (initial I frame global complexity measure) */ 0         /* rate control: Xp (initial P frame global complexity measure) */ 0         /* rate control: Xb (initial B frame global complexity measure) */ 0         /* rate control: d0i (initial I frame virtual buffer fullness) */ 0         /* rate control: d0p (initial P frame virtual buffer fullness) */ 0         /* rate control: d0b (initial B frame virtual buffer fullness) */ 2 2 11 11 /* P:  forw_hor_f_code forw_vert_f_code search_width/height */ 1 1 3  3  /* B1: forw_hor_f_code forw_vert_f_code search_width/height */ 1 1 7  7  /* B1: back_hor_f_code back_vert_f_code search_width/height */ 1 1 7  7  /* B2: forw_hor_f_code forw_vert_f_code search_width/height */ 1 1 3  3  /* B2: back_hor_f_code back_vert_f_code search_width/height */

4.5 양자화 메트릭스 파일설정 static void readquantmat() /* mpeg2enc.c */ {   int i,v;   FILE *fd;   if (iqname[0]=='-')   {     /* use default intra matrix */     load_iquant = 0;     for (i=0; i<64; i++)       intra_q[i] = default_intra_quantizer_matrix[i];   }   else     /* read customized intra matrix */     load_iquant = 1;     if (!(fd = fopen(iqname,"r")))     {       sprintf(errortext,"Couldn't open quant matrix file %s",iqname);       error(errortext);     }       fscanf(fd,"%d",&v);       if (v<1 || v>255)         error("invalid value in quant matrix");       intra_q[i] = v;     fclose(fd);

4.5 양자화 메트릭스 파일설정 if (niqname[0]=='-') {   {     /* use default non-intra matrix */     load_niquant = 0;     for (i=0; i<64; i++)       inter_q[i] = 16;   }   else     /* read customized non-intra matrix */     load_niquant = 1;     if (!(fd = fopen(niqname,"r")))     {       sprintf(errortext,"Couldn't open quant matrix file %s",niqname);       error(errortext);     }       fscanf(fd,"%d",&v);       if (v<1 || v>255)         error("invalid value in quant matrix");       inter_q[i] = v;     fclose(fd); }

4.5 양자화 메트릭스 파일설정

4.5 양자화 메트릭스 파일설정 /* default intra quantization matrix */ /* intra.mat */ 16 17 18 19 20 21 22 23 17 18 19 20 21 22 23 24 18 19 20 21 22 23 24 25 19 20 21 22 23 24 25 26 20 21 22 23 24 25 26 27 21 22 23 24 25 26 27 28 22 23 24 25 26 27 28 29 23 24 25 26 27 28 29 30