rtp 报头的大小端 可查看jrtplib 中的定义

#ifdef __HI_CODEC__ 

#else
#define WORDS_BIGENDIAN  

#endif

typedef struct rtp_packet_header {

#ifdef WORDS_BIGENDIAN
unsigned short   ph_v:2;
/* packet type                */
unsigned short   ph_p:1;
/* padding flag               */
unsigned short   ph_x:1;
/* header extension flag      */
unsigned short   ph_cc:4;
/* CSRC count                 */
unsigned short   ph_m:1;
/* marker bit                 */
unsigned short   ph_pt:7;
/* payload type               */

#else
unsigned short   ph_cc:4;
/* CSRC count                 */
unsigned short   ph_x:1;
/* header extension flag      */
unsigned short   ph_p:1;
/* padding flag               */
unsigned short   ph_v:2;
/* packet type                */
unsigned short   ph_pt:7;
/* payload type               */
unsigned short   ph_m:1;
/* marker bit                 */

#endif
uint16_t          ph_seq;
/* sequence number            */
uint32_t          ph_ts;
/* timestamp                  */
uint32_t          ph_ssrc;
/* synchronization source     */
/* The csrc list, header extension and data follow, but can't */
/* be represented in the struct.                              */
} rtp_packet_header;

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