h264的相关笔记

解析笔记

typedef struct
{
  int startcodeprefix_len;      //! 4 for parameter sets and first slice in picture, 3 for everything else (suggested)
  unsigned len;                 //! Length of the NAL unit (Excluding the start code, which does not belong to the NALU)
  unsigned max_size;            //! Nal Unit Buffer size
  int forbidden_bit;            //! should be always FALSE
  int nal_reference_idc;        //! NALU_PRIORITY_xxxx
  int nal_unit_type;            //! NALU_TYPE_xxxx    
  char *buf;                    //! contains the first byte followed by the EBSP
  unsigned short lost_packets;  //! true, if packet loss is detected
  int data_offset;
} NALU_t;
赋值方式：
      nalu->forbidden_bit = nalu->buf[0] & 0x80; //1 bit
      nalu->nal_reference_idc = nalu->buf[0] & 0x60; // 2 bit
      nalu->nal_unit_type = (nalu->buf[0]) & 0x1f;// 5 bit
//查找StartCode
static int FindStartCode2 (unsigned char *Buf)
{
 if(Buf[0]!=0 || Buf[1]!=0 || Buf[2] !=1) return 0; //判断是否为0x000001,如果是返回1
 else return 1;
}
static int FindStartCode3 (unsigned char *Buf)
{
 if(Buf[0]!=0 || Buf[1]!=0 || Buf[2] !=0 || Buf[3] !=1) return 0;//判断是否为0x00000001,如果是返回1
 else return 1;
}