安防監控視頻流媒體平臺EasyGBS能夠通過簡單的網絡攝像機通道配置，將傳統監控行業裏面的高清網絡攝像機IP Camera、NVR等GB28181國標協議輸出的設備、平臺接入到EasyGBS，EasyGBS能夠將這些視頻源的音視頻數據進行拉取，轉換爲RTMP/HLS/FLV/RTSP，進行全平臺終端H5直播（Web、Android、iOS），並且EasyGBS能夠將視頻源的直播數據對接到第三方CDN網絡，實現互聯網級別的直播分發。
在GB28181裏面，視頻請求是最重要的環節，GB28181 2016版本最主要的新增內容 估計就是請求視頻的時候支持tcp active和tcp passive， 其實早在GB28181 2014版本的時候都已經定義了tcp傳輸碼流，tcp最大的好處就是對下載的時候能保證不丟包，下面簡要說一下INVITE請求視頻的流程：
下面簡要粘貼一下抓包信息：
INVITE sip:64000000001310000001@6400000000 SIP/2.0
Call-ID: [email protected]
CSeq: 1 INVITE
From: <sip:34020000002000000001@3402000000>;tag=35565509_53173353_01b54c44-9ff9-49bf-b63a-58e0c1064b22
To: <sip:64000000001310000001@6400000000>
Max-Forwards: 70
Contact: "34020000002000000001" <sip:192.168.1.81:5060>
Subject: 64000000001310000001:0-4-0,34020000002000000001:1
Content-Type: application/sdp
Route: <sip:[email protected]:5060;lr>
Via: SIP/2.0/UDP 192.168.1.81:5060;branch=z9hG4bK01b54c44-9ff9-49bf-b63a-58e0c1064b22_53173353_34843235799148
Content-Length: 221
v=0
o=34020000002020000001 0 0 IN IP4 192.168.1.81
s=Play
c=IN IP4 192.168.1.81
t=0 0
m=video 6000 RTP/AVP 96 98 97
a=recvonly
a=rtpmap:96 PS/90000
a=rtpmap:97 MPEG4/90000
a=rtpmap:98 H264/90000
f=v/2/4///a///
SIP/2.0 100 Trying
Via: SIP/2.0/UDP 192.168.1.81:5060;branch=z9hG4bK01b54c44-9ff9-49bf-b63a-58e0c1064b22_53173353_34843235799148
From: <sip:34020000002000000001@3402000000>;tag=35565509_53173353_01b54c44-9ff9-49bf-b63a-58e0c1064b22
To: <sip:64000000001310000001@6400000000>
Call-ID: [email protected]
CSeq: 1 INVITE
Content-Length: 0
SIP/2.0 200 OK
Via: SIP/2.0/UDP 192.168.1.81:5060;branch=z9hG4bK01b54c44-9ff9-49bf-b63a-58e0c1064b22_53173353_34843235799148
Record-Route: <sip:[email protected]:5060;lr>
From: <sip:34020000002000000001@3402000000>;tag=35565509_53173353_01b54c44-9ff9-49bf-b63a-58e0c1064b22
To: <sip:64000000001310000001@6400000000>;tag=j3cF7SuJ
Call-ID: [email protected]
CSeq: 1 INVITE
Contact: <sip:[email protected]:5060>
Content-Type: application/sdp
Content-Length: 220
v=0
o=64000000001310000001 0 0 IN IP4 192.168.1.93
s=Play
c=IN IP4 192.168.1.93
t=0 0
m=video 20120 RTP/AVP 96 98 97
a=sendonly
a=rtpmap:96 PS/90000
a=rtpmap:98 H264/90000
a=rtpmap:97 MPEG4/90000
y=0000000003
ACK sip:[email protected]:5060 SIP/2.0
Call-ID: [email protected]
CSeq: 1 ACK
From: <sip:34020000002000000001@3402000000>;tag=35565509_53173353_01b54c44-9ff9-49bf-b63a-58e0c1064b22
To: <sip:64000000001310000001@6400000000>;tag=j3cF7SuJ
Max-Forwards: 70
Route: <sip:[email protected]:5060;lr>
Via: SIP/2.0/UDP 192.168.1.81:5060;branch=z9hG4bK01b54c44-9ff9-49bf-b63a-58e0c1064b22_53173353_34843344467988
Content-Length: 0
INVITE sip:34020000001310000001@3402000000 SIP/2.0
Via: SIP/2.0/UDP 192.168.1.93:5060;rport;branch=z9hG4bK-3d09000-2b0348fd-yeqPDaq1
From: <sip:[email protected]:5060>;tag=98EB157C7A7D4152B78D2B9E097AF8C9
To: <sip:34020000001310000001@3402000000>
Call-ID: 98EB157C7A7D4152B78D2B9E097AF8C9
CSeq: 12 INVITE
Contact: <sip:[email protected]:5060>
Content-Type: application/sdp
Max-Forwards: 70
Subject: 34020000001310000001:1,64000000002000000001:1
Content-Length: 258
v=0
o=64000000002000000001 0 0 IN IP4 192.168.1.93
s=Play
c=IN IP4 192.168.1.93
t=0 0
m=video 20108 TCP/RTP/AVP 96 98 97
a=recvonly
a=rtpmap:96 PS/90000
a=rtpmap:98 H264/90000
a=rtpmap:97 MPEG4/90000
a=setup:active
a=connection:new
y=0000000002
SIP/2.0 200 OK
To: <sip:34020000001310000001@3402000000>;tag=70848741_53173353_6a72b837-2678-46e9-9320-8db5a86f208c
Via: SIP/2.0/UDP 192.168.1.93:5060;rport=5060;branch=z9hG4bK-3d09000-2b0348fd-yeqPDaq1;received=192.168.1.93
CSeq: 12 INVITE
Call-ID: 98EB157C7A7D4152B78D2B9E097AF8C9
From: <sip:[email protected]:5060>;tag=98EB157C7A7D4152B78D2B9E097AF8C9
Contact: <sip:192.168.1.81:5060>
Content-Type: application/sdp
Content-Length: 245
v=0
o=64010000002020000001 0 0 IN IP4 192.168.1.81
s=Play
c=IN IP4 192.168.1.81
t=0 0
m=video 5000 TCP/RTP/AVP 96 97 98
a=sendonly
a=rtpmap:96 PS/90000
a=rtpmap:97 MPEG4/90000
a=rtpmap:98 H264/90000
a=setup:passive
a=connection:new
y=0200000025
ACK sip:34020000001310000001@3402000000 SIP/2.0
Via: SIP/2.0/UDP 192.168.1.93:5060;rport=5060;branch=z9hG4bK-3d09000-2b0348fd-yeqPDaq1;received=192.168.1.93
From: <sip:[email protected]:5060>;tag=98EB157C7A7D4152B78D2B9E097AF8C9
To: <sip:34020000001310000001@3402000000>;tag=70848741_53173353_6a72b837-2678-46e9-9320-8db5a86f208c
Call-ID: 98EB157C7A7D4152B78D2B9E097AF8C9
CSeq: 12 ACK
Max-Forwards: 70
Content-Length: 0
INVITE sip:34020000001310000001@3402000000 SIP/2.0
Via: SIP/2.0/UDP 192.168.1.93:5060;rport;branch=z9hG4bK-3d09000-16938bd4-JmZPS4tF
From: <sip:[email protected]:5060>;tag=DAD260A2BECC485BAFDDA3736EC724D9
To: <sip:34020000001310000001@3402000000>
Call-ID: DAD260A2BECC485BAFDDA3736EC724D9
CSeq: 190 INVITE
Contact: <sip:[email protected]:5060>
Content-Type: application/sdp
Max-Forwards: 70
Subject: 34020000001310000001:1,64000000002000000001:1
Content-Length: 326
v=0
o=64000000002000000001 0 0 IN IP4 192.168.1.93
s=Download
u=34020000001310000001:3
c=IN IP4 192.168.1.93
t=1495173756 1495174056
m=video 20372 TCP/RTP/AVP 96 98 97
a=recvonly
a=rtpmap:96 PS/90000
a=rtpmap:98 H264/90000
a=rtpmap:97 MPEG4/90000
a=setup:passive
a=connection:new
a=downloadspeed:8
y=1000000025
SIP/2.0 200 OK
To: <sip:34020000001310000001@3402000000>;tag=01493985_53173353_fb041e78-db58-4fec-9660-625f28bd5e9a
Via: SIP/2.0/UDP 192.168.1.93:5060;rport=5060;branch=z9hG4bK-3d09000-16938bd4-JmZPS4tF;received=192.168.1.93
CSeq: 190 INVITE
Call-ID: DAD260A2BECC485BAFDDA3736EC724D9
From: <sip:[email protected]:5060>;tag=DAD260A2BECC485BAFDDA3736EC724D9
Contact: <sip:192.168.1.81:5060>
Content-Type: application/sdp
Content-Length: 268
v=0
o=64010000002020000001 0 0 IN IP4 192.168.1.81
s=Download
c=IN IP4 192.168.1.81
t=0 0
m=video 5000 TCP/RTP/AVP 96 97 98
a=sendonly
a=rtpmap:96 PS/90000
a=rtpmap:97 MPEG4/90000
a=rtpmap:98 H264/90000
a=setup:active
a=connection:new
a=filesize:59770877
y=1200000016
ACK sip:34020000001310000001@3402000000 SIP/2.0
Via: SIP/2.0/UDP 192.168.1.93:5060;rport=5060;branch=z9hG4bK-3d09000-16938bd4-JmZPS4tF;received=192.168.1.93
From: <sip:[email protected]:5060>;tag=DAD260A2BECC485BAFDDA3736EC724D9
To: <sip:34020000001310000001@3402000000>;tag=01493985_53173353_fb041e78-db58-4fec-9660-625f28bd5e9a
Call-ID: DAD260A2BECC485BAFDDA3736EC724D9
CSeq: 190 ACK
Max-Forwards: 70
Content-Length: 0
流媒體這塊就需要自己做處理了，一般檢測的時候需要等待幾秒鐘，檢測軟件SPVMN不是那麼快速，還有就是tcp active的時候，spvmn的端口不是協議中的端口，所以也不需要針對tcp端口進行篩選。
