基于mpeg-4和rtp的網(wǎng)絡(luò)視頻監(jiān)控系統(tǒng)研究-資料下載頁
2025-06-22 06:25本頁面
【正文】 計(jì)數(shù)方法則避免了對(duì) 4 的倍數(shù)的有效性校驗(yàn)）。RTP/RTCP（實(shí)時(shí)傳輸協(xié)議/實(shí)時(shí)傳輸控制協(xié)議）基于UDP派生出的協(xié)議，并增加了對(duì)實(shí)時(shí)傳輸?shù)目刂?。一般用于網(wǎng)上傳輸實(shí)時(shí)視頻數(shù)據(jù)，比如遠(yuǎn)程視頻監(jiān)控，視頻點(diǎn)播等。有一本名叫《多媒體網(wǎng)絡(luò)傳輸協(xié)議》的書上對(duì)此2個(gè)協(xié)議的結(jié)構(gòu)和原理做了比較詳細(xì)的介紹，好象是清華大學(xué)出版社出版的。??? 我去年做遠(yuǎn)程視頻監(jiān)控系統(tǒng)時(shí)，曾用基于2個(gè)協(xié)議，用Wonsock工具封裝了一個(gè)網(wǎng)絡(luò)傳輸動(dòng)態(tài)連接庫，專門用于局域網(wǎng)組播傳輸實(shí)時(shí)視頻數(shù)據(jù)。以下是我針對(duì)此2個(gè)協(xié)議定義的相關(guān)C結(jié)構(gòu)。??? /*Current protocol version. */define RTP_VERSION??? 2define MIN_SEQUENTIAL? 1define RTP_SEQ_MOD (116)define RTP_MAX_SDES 255????? /* maximum text length for SDES */define MID_BUFFER_NUM?? 2define MAX_DROPOUT?? 25typedef enum {??? RTCP_SR?? = 200,??? RTCP_RR?? = 201,??? RTCP_SDES = 202,??? RTCP_BYE? = 203,??? RTCP_APP? = 204} rtcp_type_t。typedef enum {?? RTCP_SDES_END?? = 0,?? RTCP_SDES_CNAME = 1,?? RTCP_SDES_NAME? = 2,?? RTCP_SDES_EMAIL = 3,?? RTCP_SDES_PHONE = 4,?? RTCP_SDES_LOC?? = 5,?? RTCP_SDES_TOOL? = 6,?? RTCP_SDES_NOTE? = 7,?? RTCP_SDES_PRIV? = 8} rtcp_sdes_type_t。/*?* RTP data header?*/typedef struct {?? unsigned int version:2。?? /* protocol version */?? unsigned int p:1。???????? /* padding flag */?? unsigned int x:1。???????? /* header extension flag */?? unsigned int cc:4。??????? /* CSRC count */?? unsigned int m:1。???????? /* marker bit */?? unsigned int pt:7。??????? /* payload type */?? u_int16 seq。????????????? /* sequence number */?? u_int32 ts。?????????????? /* timestamp */?? u_int32 ssrc。???????????? /* synchronization source */?? u_int32 csrc[1]。????????? /* optional CSRC list */} rtp_hdr_t。/*?* RTCP mon header word?*/typedef struct {?? unsigned int version:2。?? /* protocol version */?? unsigned int p:1。???????? /* padding flag */?? unsigned int count:5。???? /* varies by packet type */?? unsigned int pt:8。??????? /* RTCP packet type */?? u_int16 length。?????????? /* pkt len in words, w/o this word */} rtcp_mon_t。/*?* Bigendian mask for version, padding bit and packet type pair?*/define RTCP_VALID_MASK (0xc000 | 0x2000 | 0xfe)define RTCP_VALID_VALUE ((RTP_VERSION 14) | RTCP_SR)/*?* Reception report block?*/typedef struct {?? u_int32 ssrc。???????????? /* data source being reported */?? unsigned int fraction:8。? /* fraction lost since last SR/RR */?? int lost:24。????????????? /* cumul. no. pkts lost (signed!) */?? u_int32 last_seq。???????? /* extended last seq. no. received */?? u_int32 jitter。?????????? /* interarrival jitter */?? u_int32 lsr。????????????? /* last SR packet from this source */?? u_int32 dlsr。???????????? /* delay since last SR packet */} rtcp_rr_t。/*?* SDES item?*/typedef struct {?? u_int8 type。????????????? /* type of item (rtcp_sdes_type_t) */?? u_int8 length。??????????? /* length of item (in octets) */?? char data[1]。???????????? /* text, not nullterminated */} rtcp_sdes_item_t。/*?* One RTCP packet?*/typedef struct {?? rtcp_mon_t mon。???? /* mon header */?? union {????? /* sender report (SR) */????? struct {???????? u_int32 ssrc。???? /* sender generating this report */???????? u_int32 ntp_sec。? /* NTP timestamp */???????? u_int32 ntp_frac。???????? u_int32 rtp_ts。?? /* RTP timestamp */???????? u_int32 psent。??? /* packets sent */???????? u_int32 osent。??? /* octets sent */???????? rtcp_rr_t rr[1]。? /* variablelength list */?????? } sr。?????? /* reception report (RR) */?????? struct {????????? u_int32 ssrc。???? /* receiver generating this report */????????? rtcp_rr_t rr[1]。? /* variablelength list */?????? } rr。?????? /* source description (SDES) */?????? struct rtcp_sdes {????????? u_int32 src。????? /* first SSRC/CSRC */????????? rtcp_sdes_item_t item[1]。 /* list of SDES items */?????? } sdes。?????? /* BYE */?????? struct {????????? u_int32 src[1]。?? /* list of sources */?????????????????????????? /* can39。t express trailing text for reason */?????? } bye。?? } r。} rtcp_t。
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