【正文】 都應(yīng)正常播放，如果某些需要顯示給用戶的參數(shù)無法獲得，則顯示為空。 用戶代理（User Agent）參數(shù)要求為了使得服務(wù)器端能夠向終端發(fā)送合適的碼流，服務(wù)器需要獲得終端能力，包括終端的屏幕尺寸、CPU 處理能力、內(nèi)存大小、屏幕分辨率、播放器類型等信息。終端在訪問流媒體門戶和下載門戶時，要求在 HTTP 請求的報(bào)頭中將正確的 User Agent 信息發(fā)給門戶，必須包括終端型號、軟件版本，推薦包括播放器名稱和版本信息，必須符合 RFC2616 的定義。User Agent 的格式和最大長度限制必須符合中國移動《移動終端 技術(shù)規(guī)范》的要求，由若干“參數(shù)條目/參數(shù)條目屬性”組合而成，并以“空格”分開。舉例如下：User Agent：Nokia7650/ SymbianOS/ Series60/ Release/ Browser/ Profile/ Configuration/在與流媒體服務(wù)器交互過程中，要求播放器在 RTSP 消息的報(bào)頭攜帶 User Agent，包括播放器的基本信息，必須符合 RFC2616 的定義，其格式必須符合“播放器名稱/版本”舉例如下：UserAgent：RealMedia Player/ RTCP協(xié)議消息要求RTCP 協(xié)議消息有如下幾種類型，詳見 RFC 3550 和 RFC 3551：SR：發(fā)送端報(bào)告，所謂發(fā)送端是指發(fā)出 RTP 數(shù)據(jù)報(bào)的源端，發(fā)送端同時也可以是接收端。RR：接收端報(bào)告，所謂接收端是指僅接收但不發(fā)送 RTP 數(shù)據(jù)報(bào)的終端。 SDES：源描述，主要功能是作為會話成員有關(guān)標(biāo)識信息的載體，如用戶名、郵件地址、電話號碼等，此外還具有向會話成員傳達(dá)會話控制信息的功能。 BYE：通知離開，主要功能是通知會話中的其他成員自己將退出會話。 APP：由應(yīng)用程序自己定義，主要解決 RTCP 的擴(kuò)展性問題。發(fā)送媒體流的源端將周期性地產(chǎn)生發(fā)送端報(bào)告 SR，該 RTCP 數(shù)據(jù)報(bào)含有不同媒體流間的同步信息，以及已經(jīng)發(fā)送的數(shù)據(jù)報(bào)和字節(jié)的計(jì)數(shù)，接收端根據(jù)這些信息可以估計(jì)出實(shí)際的數(shù)據(jù)傳輸速率。另一方面，接收端會向所有已知的發(fā)送端發(fā)送接收端報(bào)告 RR，該 RTCP 數(shù)據(jù)報(bào)含有已接收數(shù)據(jù)報(bào)的最大序列18 / 39號、丟失的數(shù)據(jù)報(bào)數(shù)目、延時抖動和時間戳等重要信息，發(fā)送端應(yīng)用根據(jù)這些信息可以估計(jì)出往返時延，并且可以根據(jù)數(shù)據(jù)報(bào)丟失概率和時延抖動情況動態(tài)調(diào)整發(fā)送速率，以改善網(wǎng)絡(luò)擁塞狀況，或者根據(jù)網(wǎng)絡(luò)狀況平滑地調(diào)整應(yīng)用程序的服務(wù)質(zhì)量。類似于 RTP 數(shù)據(jù)包，每個 RTCP 包以固定部分開始，緊接著的是可變長結(jié)構(gòu)元素，但以一個 32位邊界結(jié)束。(1) SR0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+++++++++++++++++++++++++++++++++|V=2|P| RC | PT=SR=200 | length | header+++++++++++++++++++++++++++++++++| SSRC of sender |+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+| NTP timestamp, most significant word | sender+++++++++++++++++++++++++++++++++ info| NTP timestamp, least significant word |+++++++++++++++++++++++++++++++++| RTP timestamp |+++++++++++++++++++++++++++++++++| sender39。s packet count |+++++++++++++++++++++++++++++++++| sender39。s octet count |+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+| SSRC_1 (SSRC of first source) | report+++++++++++++++++++++++++++++++++ block| fraction lost | cumulative number of packets lost | 1++++++++++++++++++++++++++++++++| extended highest sequence number received |+++++++++++++++++++++++++++++++++| interarrival jitter |+++++++++++++++++++++++++++++++++| last SR (LSR) |+++++++++++++++++++++++++++++++++| delay since last SR (DLSR) |+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+| SSRC_2 (SSRC of second source) | report+++++++++++++++++++++++++++++++++ block: ... : 2+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+| profilespecific extensions |+++++++++++++++++++++++++++++++++19 / 39參數(shù) 含義 協(xié)議要求 移動要求V = 2 Protocol version 必選 必選P Padding 必選 必選RC Receiver report Count 必選 必選PT = 200 Packet Type 必選 必選Length Length of RTCP Packet 必選 必選SSRC Synchronization Source identifier 必選 必選NTP timestampNTP timestamp 必選 必選RTP timestampRTP timestamp 必選 必選sender39。s packet countsender39。s packet count 必選 必選sender39。s octet countsender39。s octet count 必選 必選SSRC_n source identifier 必選 必選FR Fraction Lost = of lost packets/ of expected packets必選 必選CNPL Cumulative Number of Packet Lost 必選 必選EHSNR Extended Highest Sequence Number Received必選 必選IJ Interarrival Jitter 必選 必選LSR Last SR timestamp 必選 必選DSLSR Delay Since Last SR 必選 必選(2) RR要求終端上報(bào) RR 的間隔不超過 5 秒。對于支持動態(tài)碼率適配的終端，要求上報(bào) RR 的間隔不超過2 秒。0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+++++++++++++++++++++++++++++++++|V=2|P| RC | PT=RR=201 | length | header+++++++++++++++++++++++++++++++++| SSRC of packet sender |+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+| SSRC_1 (SSRC of first source) | report+++++++++++++++++++++++++++++++++ block| fraction lost | cumulative number of packets lost | 1+++++++++++++++++++++++++++++++++| extended highest sequence number received |+++++++++++++++++++++++++++++++++| interarrival jitter |+++++++++++++++++++++++++++++++++20 / 39| last SR (LSR) |+++++++++++++++++++++++++++++++++| delay since last SR (DLSR) |+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+| SSRC_2 (SSRC of second source) | report+++++++++++++++++++++++++++++++++ block: ... : 2+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+| profilespecific extensions |++++++++++