NAL Unit 구조

VM14에 나와있는 NAL 유닛 구조입니다.

실제 스트림으로 나오는 것을 캡쳐 해보면, startcode(32bit), NAL Header(8bit) 

RBSP 로 이루어 짐을 알 수 있습니다.

 

typedef struct

 {

   int     startcodeprefix_len;

  (Excluding the start code, which does not belong to the NALU)
   unsigned  len;                   

   unsigned  max_size;              //!< NAL Unit Buffer size

   NaluType  nal_unit_type;         //!< NALU_TYPE_xxxx

   NalRefIdc nal_reference_idc;     //!< NALU_PRIORITY_xxxx

   int       forbidden_bit;         //!< should be always FALSE

   byte     *buf;                   //!< contains the first byte followed by the EBSP

} NALU_t;



typedef enum {

  NALU_PRIORITY_HIGHEST     = 3,

  NALU_PRIORITY_HIGH        = 2,

  NALU_PRIORITY_LOW         = 1,

  NALU_PRIORITY_DISPOSABLE  = 0

} NalRefIdc;


//! values for nal_unit_type

typedef enum {

  NALU_TYPE_SLICE    = 1,

  NALU_TYPE_DPA      = 2,

  NALU_TYPE_DPB      = 3,

  NALU_TYPE_DPC      = 4,

  NALU_TYPE_IDR      = 5,

  NALU_TYPE_SEI      = 6,

  NALU_TYPE_SPS      = 7,

  NALU_TYPE_PPS      = 8,

  NALU_TYPE_AUD      = 9,

  NALU_TYPE_EOSEQ    = 10,

  NALU_TYPE_EOSTREAM = 11,

  NALU_TYPE_FILL     = 12

} NaluType;