h264 SPS PPS 解析，C代码实现，已验证

/*************************************************************************************** ***************************************************************************************/ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> /* for uint32_t, etc */ #include "sps_pps.h" /* report level */ #define RPT_ERR (1) // error, system error #define RPT_WRN (2) // warning, maybe wrong, maybe OK #define RPT_INF (3) // important information #define RPT_DBG (4) // debug information static int rpt_lvl = RPT_WRN; /* report level: ERR, WRN, INF, DBG */ /* report micro */ #define RPT(lvl, ...) \ do { \ if(lvl <= rpt_lvl) { \ switch(lvl) { \ case RPT_ERR: \ fprintf(stderr, "\"%s\" line %d [err]: ", __FILE__, __LINE__); \ break; \ case RPT_WRN: \ fprintf(stderr, "\"%s\" line %d [wrn]: ", __FILE__, __LINE__); \ break; \ case RPT_INF: \ fprintf(stderr, "\"%s\" line %d [inf]: ", __FILE__, __LINE__); \ break; \ case RPT_DBG: \ fprintf(stderr, "\"%s\" line %d [dbg]: ", __FILE__, __LINE__); \ break; \ default: \ fprintf(stderr, "\"%s\" line %d [???]: ", __FILE__, __LINE__); \ break; \ } \ fprintf(stderr, __VA_ARGS__); \ fprintf(stderr, "\n"); \ } \ } while(0) /******************************************** *define here ********************************************/ #define SPS_PPS_DEBUG #undef SPS_PPS_DEBUG #define MAX_LEN 32 /******************************************** *functions ********************************************/ /** * @brief Function get_1bit() 读1个bit * @param[in] h get_bit_context structrue * @retval 0: success, -1 : failure * @pre * @post */ static int get_1bit(void *h) { get_bit_context *ptr = (get_bit_context *)h; int ret = 0; uint8_t *cur_char = NULL; uint8_t shift; if(NULL == ptr) { RPT(RPT_ERR, "NULL pointer"); ret = -1; goto exit; } cur_char = ptr->buf + (ptr->bit_pos >> 3); shift = 7 - (ptr->cur_bit_pos); ptr->bit_pos++; ptr->cur_bit_pos = ptr->bit_pos & 0x7; ret = ((*cur_char) >> shift) & 0x01; exit: return ret; } /** * @brief Function get_bits() 读n个bits，n不能超过32 * @param[in] h get_bit_context structrue * @param[in] n how many bits you want? * @retval 0: success, -1 : failure * @pre * @post */ static int get_bits(void *h, int n) { get_bit_context *ptr = (get_bit_context *)h; uint8_t temp[5] = {0}; uint8_t *cur_char = NULL; uint8_t nbyte; uint8_t shift; uint32_t result; uint64_t ret = 0; if(NULL == ptr) { RPT(RPT_ERR, "NULL pointer"); ret = -1; goto exit; } if(n > MAX_LEN) { n = MAX_LEN; } if((ptr->bit_pos + n) > ptr->total_bit) { n = ptr->total_bit- ptr->bit_pos; } cur_char = ptr->buf+ (ptr->bit_pos>>3); nbyte = (ptr->cur_bit_pos + n + 7) >> 3; shift = (8 - (ptr->cur_bit_pos + n))& 0x07; if(n == MAX_LEN) { RPT(RPT_DBG, "12(ptr->bit_pos(:%d) + n(:%d)) > ptr->total_bit(:%d)!!! ",\ ptr->bit_pos, n, ptr->total_bit); RPT(RPT_DBG, "0x%x 0x%x 0x%x 0x%x", (*cur_char), *(cur_char+1),*(cur_char+2),*(cur_char+3)); } memcpy(&temp[5-nbyte], cur_char, nbyte); ret = (uint32_t)temp[0] << 24; ret = ret << 8; ret = ((uint32_t)temp[1]<<24)|((uint32_t)temp[2] << 16)\ |((uint32_t)temp[3] << 8)|temp[4]; ret = (ret >> shift) & (((uint64_t)1<<n) - 1); result = ret; ptr->bit_pos += n; ptr->cur_bit_pos = ptr->bit_pos & 0x7; exit: return result; } /** * @brief Function parse_codenum() 指数哥伦布编码解析，参考h264标准第9节 * @param[in] buf * @retval code_num * @pre * @post */ static int parse_codenum(void *buf) { uint8_t leading_zero_bits = -1; uint8_t b; uint32_t code_num = 0; for(b=0; !b; leading_zero_bits++) { b = get_1bit(buf); } code_num = ((uint32_t)1 << leading_zero_bits) - 1 + get_bits(buf, leading_zero_bits); return code_num; } /** * @brief Function parse_ue() 指数哥伦布编码解析 ue(),参考h264标准第9节 * @param[in] buf sps_pps parse buf * @retval code_num * @pre * @post */ static int parse_ue(void *buf) { return parse_codenum(buf); } /** * @brief Function parse_se() 指数哥伦布编码解析 se(), 参考h264标准第9节 * @param[in] buf sps_pps parse buf * @retval code_num * @pre * @post */ static int parse_se(void *buf) { int ret = 0; int code_num; code_num = parse_codenum(buf); ret = (code_num + 1) >> 1; ret = (code_num & 0x01)? ret : -ret; return ret; } /** * @brief Function get_bit_context_free() 申请的get_bit_context结构内存释放 * @param[in] buf get_bit_context buf * @retval none * @pre * @post */ static void get_bit_context_free(void *buf) { get_bit_context *ptr = (get_bit_context *)buf; if(ptr) { if(ptr->buf) { free(ptr->buf); } free(ptr); } } /** * @brief Function de_emulation_prevention() 解竞争代码 * @param[in] buf get_bit_context buf * @retval none * @pre * @post * @note: * 调试时总是发现vui.time_scale值特别奇怪，总是16777216，后来查询原因如下: * http://www.cnblogs.com/eustoma/archive/2012/02/13/2415764.html * H.264编码时，在每个NAL前添加起始码 0x000001，解码器在码流中检测到起始码，当前NAL结束。 * 为了防止NAL内部出现0x000001的数据，h.264又提出'防止竞争 emulation prevention"机制， * 在编码完一个NAL时，如果检测出有连续两个0x00字节，就在后面插入一个0x03。 * 当解码器在NAL内部检测到0x000003的数据，就把0x03抛弃，恢复原始数据。 * 0x000000 >>>>>> 0x00000300 * 0x000001 >>>>>> 0x00000301 * 0x000002 >>>>>> 0x00000302 * 0x000003 >>>>>> 0x00000303 */ static void *de_emulation_prevention(void *buf) { get_bit_context *ptr = NULL; get_bit_context *buf_ptr = (get_bit_context *)buf; int i = 0, j = 0; uint8_t *tmp_ptr = NULL; int tmp_buf_size = 0; int val = 0; if(NULL == buf_ptr) { RPT(RPT_ERR, "NULL ptr"); goto exit; } ptr = (get_bit_context *)malloc(sizeof(get_bit_context)); if(NULL == ptr) { RPT(RPT_ERR, "NULL ptr"); goto exit; } memcpy(ptr, buf_ptr, sizeof(get_bit_context)); ptr->buf = (uint8_t *)malloc(ptr->buf_size); if(NULL == ptr->buf) { RPT(RPT_ERR, "NULL ptr"); goto exit; } memcpy(ptr->buf, buf_ptr->buf, buf_ptr->buf_size); tmp_ptr = ptr->buf; tmp_buf_size = ptr->buf_size; for(i=0; i<(tmp_buf_size-2); i++) { /*检测0x000003*/ val = (tmp_ptr[i]^0x00) + (tmp_ptr[i+1]^0x00) + (tmp_ptr[i+2]^0x03); if(val == 0) { /*剔除0x03*/ for(j=i+2; j<tmp_buf_size-1; j++) { tmp_ptr[j] = tmp_ptr[j+1]; } /*相应的bufsize要减小*/ ptr->buf_size--; } } /*重新计算total_bit*/ ptr->total_bit = ptr->buf_size << 3; return (void *)ptr; exit: get_bit_context_free(ptr); return NULL; } /** * @brief Function get_bit_