目录
MRCPv2 是 Media Resource Control Protocol Version 2 (MRCPv2)的缩写，这一篇翻译RFC6787一节4.3. SIP Session Example
4.3. SIP Session Example
第一个示例展示了使用 SIP 路由到适当资源的强大功能。 在示例中，请注意在对 [email protected] 的 INVITE 中使用了对域语音服务器服务的请求。 域中的 SIP 路由机制找到实际服务器 [email protected]，它在 200 OK 中返回。 请注意，“cmid”在第 4.4 节中定义。
此示例交换为合成器添加资源控制通道。 由于合成器也会生成音频流，因此此交互还会创建一个只接收实时协议 (RTP) [RFC3550] 媒体会话，供服务器将音频发送到。 带有媒体源/接收器的 SIP 对话独立于 MRCP，因此未显示。
Example: Add Synthesizer Control Channel
C->S:
INVITE sip:[email protected] SIP/2.0
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf1
Max-Forwards:6
To:MediaServer <sip:[email protected]>
From:sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314161 INVITE
Contact:<sip:[email protected]>
Content-Type:application/sdp
Content-Length:...
v=0
o=sarvi 2890844526 2890844526 IN IP4 192.0.2.12
s=-
c=IN IP4 192.0.2.12
t=0 0
m=application 9 TCP/MRCPv2 1 # 这里制定了MRCP协议
a=setup:active # 客户端发起，active
a=connection:new # 是一个新的链接
a=resource:speechsynth # 资源是 语音合成
a=cmid:1
m=audio 49170 RTP/AVP 0
a=rtpmap:0 pcmu/8000
a=recvonly #注意 语音合成， 客户端是只收语音流
a=mid:1
S->C:
SIP/2.0 200 OK
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf1;received=192.0.32.10
To:MediaServer <sip:[email protected]>;tag=62784
From:sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314161 INVITE
Contact:<sip:[email protected]>
Content-Type:application/sdp
Content-Length:...
v=0
o=- 2890842808 2890842808 IN IP4 192.0.2.11
s=-
c=IN IP4 192.0.2.11
t=0 0
m=application 32416 TCP/MRCPv2 1
a=setup:passive # 服务端接受，passive
a=connection:new
a=channel:32AECB234338@speechsynth # 服务端生成一个channel
a=cmid:1
m=audio 48260 RTP/AVP 0
a=rtpmap:0 pcmu/8000
a=sendonly #注意 语音合成， 服务端是只发语音流
a=mid:1
C->S:
ACK sip:[email protected] SIP/2.0
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf2
Max-Forwards:6
To:MediaServer <sip:[email protected]>;tag=62784
From:Sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314161 ACK
Content-Length:0
Example: Add Recognizer
C->S:
INVITE sip:[email protected] SIP/2.0
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf3
Max-Forwards:6
To:MediaServer <sip:[email protected]>;tag=62784
From:sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314162 INVITE
Contact:<sip:[email protected]>
Content-Type:application/sdp
Content-Length:...
v=0
o=sarvi 2890844526 2890844527 IN IP4 192.0.2.12
s=-
c=IN IP4 192.0.2.12
t=0 0
m=application 9 TCP/MRCPv2 1
a=setup:active
a=connection:existing # 注意这里的状态是existing,不再是new
a=resource:speechsynth
a=cmid:1
m=audio 49170 RTP/AVP 0 96
a=rtpmap:0 pcmu/8000
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15
a=sendrecv #注意 改成了收发同时
a=mid:1
m=application 9 TCP/MRCPv2 1
a=setup:active
a=connection:existing
a=resource:speechrecog # 添加一个新的
a=cmid:1
S->C:
SIP/2.0 200 OK
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf3;received=192.0.32.10
To:MediaServer <sip:[email protected]>;tag=62784
From:sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314162 INVITE
Contact:<sip:[email protected]>
Content-Type:application/sdp
Content-Length:...
v=0
o=- 2890842808 2890842809 IN IP4 192.0.2.11
s=-
c=IN IP4 192.0.2.11
t=0 0
m=application 32416 TCP/MRCPv2 1
a=setup:passive
a=connection:existing
a=channel:32AECB234338@speechsynth
a=cmid:1
m=audio 48260 RTP/AVP 0 96
a=rtpmap:0 pcmu/8000
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15
a=sendrecv
a=mid:1
m=application 32416 TCP/MRCPv2 1
a=setup:passive
a=connection:existing
a=channel:32AECB234338@speechrecog # 新增加的语音识别channel
a=cmid:1
C->S:
ACK sip:[email protected] SIP/2.0
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf4
Max-Forwards:6
To:MediaServer <sip:[email protected]>;tag=62784
From:Sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314162 ACK
Content-Length:0
此示例从上图继续，并为识别器分配一个额外的资源控制通道。
由于识别器需要接收音频流以进行识别，因此此交互还将音频流更新为 sendrecv，使其成为双向 RTP 媒体会话。
Example: Deallocate Recognizer
C->S:
INVITE sip:[email protected] SIP/2.0
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf5
Max-Forwards:6
To:MediaServer <sip:[email protected]>;tag=62784
From:sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314163 INVITE
Contact:<sip:[email protected]>
Content-Type:application/sdp
Content-Length:...
v=0
o=sarvi 2890844526 2890844528 IN IP4 192.0.2.12
s=-
c=IN IP4 192.0.2.12
t=0 0
m=application 9 TCP/MRCPv2 1
a=resource:speechsynth
a=cmid:1
m=audio 49170 RTP/AVP 0
a=rtpmap:0 pcmu/8000
a=recvonly
a=mid:1
m=application 0 TCP/MRCPv2 1
a=resource:speechrecog
a=cmid:1
S->C:
SIP/2.0 200 OK
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf5;received=192.0.32.10
To:MediaServer <sip:[email protected]>;tag=62784
From:sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314163 INVITE
Contact:<sip:[email protected]>
Content-Type:application/sdp
Content-Length:...
v=0
o=- 2890842808 2890842810 IN IP4 192.0.2.11
s=-
c=IN IP4 192.0.2.11
t=0 0
m=application 32416 TCP/MRCPv2 1
a=channel:32AECB234338@speechsynth
a=cmid:1
m=audio 48260 RTP/AVP 0
a=rtpmap:0 pcmu/8000
a=sendonly
a=mid:1
m=application 0 TCP/MRCPv2 1
a=channel:32AECB234338@speechrecog
a=cmid:1
C->S:
ACK sip:[email protected] SIP/2.0
Via:SIP/2.0/TCP client.atlanta.example.com:5060;
branch=z9hG4bK74bf6
Max-Forwards:6
To:MediaServer <sip:[email protected]>;tag=62784
From:Sarvi <sip:[email protected]>;tag=1928301774
Call-ID:a84b4c76e66710
CSeq:314163 ACK
Content-Length:0
此示例从上图继续并取消分配识别器通道。 由于识别器不再需要接收音频流，因此此交互还将 RTP 媒体会话更新为 recvonly。