H.264

H.264

#include <stdio.h>
#include <stdlib.h>

#define bool  unsigned int
#define true  1
#define false 0

int profile = 0;
int level   = 0;
int width   = 0;
int height  = 0;

int pos;
char data[8];

int getNextBit(){
	int mask = 1 << (7 - (pos & 7));
	int index = pos >> 3;
	pos++;
	return ((data[index] & mask) == 0) ? 0 : 1;
}

int ev(bool flag) {
    int bitcount = 0;
    while (getNextBit() == 0) {
        bitcount++;
    }
    int result = 1;
	int i = 0;
    for (i = 0; i < bitcount; i++) {
        int b = getNextBit();
        result = result * 2 + b;
    }
    result--;
    if (flag) {
        result = (result + 1) / 2 * (result % 2 == 0 ? -1 : 1);
    }
    return result;
}

int uev() {
    return ev(false);
}

int sev() {
    return ev(true);
}

int getU(int bits) {
    int result = 0;
	int i;
    for (i = 0; i < bits; i++) {
        result = result * 2 + getNextBit();
    }
    //printf("getU(%d) = %d\n" ,bits, result);
    return result;
}

void parse() {
    pos = 0;
    int profile_idc = getU(8);
    profile = profile_idc;
	int constraint_set0_flag = getU(1);
    int constraint_set1_flag = getU(1);
    int constraint_set2_flag = getU(1);
    int constraint_set3_flag = getU(1);
    int reserved_zero_4bits = getU(4);
    int level_idc = getU(8);
	level = level_idc;
    int seq_parameter_set_id = uev();
    int log2_max_frame_num_minus4 = uev();
    int pict_order_cnt_type = uev();
	int log2_max_pic_order_cnt_lab_minus4;
	int delta_pic_order_always_zero_flag;
	int offset_for_non_ref_pic;
	int offset_for_top_to_bttom_field;
	
    if (pict_order_cnt_type == 0) {
        log2_max_pic_order_cnt_lab_minus4 = uev();
    } else if (pict_order_cnt_type == 1) {
        delta_pic_order_always_zero_flag = getU(1);
        offset_for_non_ref_pic = sev();
        offset_for_top_to_bttom_field = sev();
        int n = uev();
		int i = 0;
        for (i = 0; i < n; i++){
            sev();
        }
    }
    int num_ref_frames = uev();
    int gaps_in_frame_num_value_allowed_flag = getU(1);
	int pic_width_in_mbs_minus1 = uev();
	int pic_height_in_mbs_minus1 = uev();
	
    int pic_width = (pic_width_in_mbs_minus1 + 1) * 16;
    int pic_height = (pic_height_in_mbs_minus1 + 1) * 16;
    int frame_mbs_only_flag = getU(1);
	width = pic_width;
	height = pic_height;
	
	//Debug
	printf("\n");
	printf("profile_idc                          = %d\n", profile_idc);
	printf("constraint_set0_flag                 = %d\n", constraint_set0_flag);
	printf("constraint_set1_flag                 = %d\n", constraint_set1_flag);
	printf("constraint_set2_flag                 = %d\n", constraint_set2_flag);
	printf("constraint_set3_flag                 = %d\n", constraint_set3_flag);
	printf("reserved_zero_4bits                  = %d\n", reserved_zero_4bits);
	printf("level_idc                            = %d\n", level_idc);
	printf("seq_parameter_set_id                 = %d\n", seq_parameter_set_id);
	printf("log2_max_frame_num_minus4            = %d\n", log2_max_frame_num_minus4);
    printf("pict_order_cnt_type                  = %d\n" , pict_order_cnt_type);
	printf("log2_max_pic_order_cnt_lab_minus4    = %d\n", log2_max_pic_order_cnt_lab_minus4);
	printf("delta_pic_order_always_zero_flag     = %d\n", delta_pic_order_always_zero_flag);
	printf("offset_for_non_ref_pic               = %d\n", offset_for_non_ref_pic);
	printf("offset_for_top_to_bttom_field        = %d\n", offset_for_top_to_bttom_field);
	printf("num_ref_frames                       = %d\n", num_ref_frames);
	printf("gaps_in_frame_num_value_allowed_flag = %d\n", gaps_in_frame_num_value_allowed_flag);
	printf("pic_width_in_mbs_minus1              = %d\n", pic_width_in_mbs_minus1);
	printf("pic_height_in_mbs_minus1             = %d\n", pic_height_in_mbs_minus1);
	printf("frame_mbs_only_flag                  = %d\n", frame_mbs_only_flag);
	
}

const int BitSize = sizeof(int) * 2;
void dtob(int x) {
  int bit = 1, i;
  char c[BitSize];
 
  for (i = 0; i < BitSize; i++) {
    if (x & bit)
      c[i] = '1';
    else
      c[i] = '0';
    bit <<= 1;
  }
  printf(" : ");
  for ( i = BitSize - 1; i >= 0; i-- ) {
      putchar(c[i]);
  }
  printf("\n");
}



int main(void){
	
    FILE *fp;
    int c;
	int prev1=0;
	int prev2=0;
	int prev3=0;
	int count = 0;
	bool isStart = false;
	bool isSPS   = false;
	bool isPPS   = false;
    if ((fp = fopen( "es.264", "r")) == NULL) {
        fprintf(stderr, "Can't Open File\n");
        exit(-1);
    }
	
	printf("\n=============Debug==============\n");
    while ((c = fgetc(fp)) != EOF){
		if (isSPS == true){
			count++;
			printf("0x%02x ", c);
			data[count-1] = c;
			dtob(c);
		}
		
		if (isPPS == true){
			printf("0x%02x ", c);
			dtob(c);
		}
		
		if (isStart == true){
			if (7 == (c & 0x1F)){
				printf("SPS\n");
				isSPS = true;
			}
			if (8 == (c & 0x1F)){
				printf("PPS\n");
				isPPS = true;
			}
			isStart = false;
		}
		
		if (prev1 == 0x00 && prev2 == 0x00 && prev3 == 0x00 && c == 0x01){
			isStart = true;
			isSPS = false;
			isPPS = false;
		}
		
		prev3 = prev2;
		prev2 = prev1;
		prev1 = c;
		
	}
    fclose(fp);
	parse();
	printf("\n=============Answer==============\n");
	printf("\n");
	printf("Width x Height = %d x %d\n", width, height);
	printf("Profile = %d\n", profile);
	printf("Level   = %d\n", level);
	return 0;
}