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RTCP Implemented

The RTP control protocol (RTCP) has been implemented in the trunk.

RTCP allows to monitor RTP delivery. The protocol is based on periodic transmission of control packets. The primary function is to provide statistical reports such as Sender Report (SR) and Receiver Report (RR).

There are a number of options to configure.

1. Enable RTCP support
Currently RTCP is disabled by default, you should enable it first from unimrcpclient.xml and/or unimrcpserver.xml configuration files.
        <!-- enable/disable rtcp support -->
        <param name="rtcp" value="1"/>

2. Transmission of RTCP reports
The default transmission interval is 5 sec. This is the period RTCP reports are generated and sent with. Typically, RTCP traffic bandwidth should be fixed at 5% of overall RTP/RTCP session bandwidth. Anyway, you can adjust the interval by the following parameter. To disable periodic transmission set it 0.
        <!-- rtcp transmission interval in msec  -->
        <param name="rtcp-tx-interval" value="5000"/>

3. Transmission of an RTCP BYE packet
According to the specification (RFC3550), a participant should sent an RTCP BYE packet when he wishes to leave an RTP session. Typically, RTP is used in conjunction with higher level session management protocols such as SIP, H323, which provide own mechanisms for the participants to join/leave a session. Therefore, presence of RTCP BYE packet is usually optional.
However, the role of RTCP BYE in an MRCP environment was re-defined by well known vendor(s). It's intended to indicate end of input (utterance). All the mentioned options are supported by UniMRCP now.
        <!-- rtcp bye policies
             0 - disable rtcp bye
             1 - send rtcp bye at the end of session
             2 - send rtcp bye also at the end of each talkspurt (input)
        <param name="rtcp-bye" value="1"/>

4. Reception of RTCP packets
Currently this routine dumps received RTCP packets in the logs and it is mainly helpful for monitoring and debugging.
The period, which is used to check for new RTCP messages, can be adjusted by the following parameter. To disable the reception of RTCP packets set it 0.
        <!-- period (timeout) to check for new rtcp messages in msec  -->
        <param name="rtcp-rx-resolution" value="1000"/>

Give it a try by choosing options which best fit your needs.

Arsen Chaloyan
The author of UniMRCP

Recorder Resource Supported

Now UniMRCP supports recorder resource too.

This resource allows to capture and store audio and video streams. The
use cases are evident for telephony platforms which provide call
recording and voice mail functionality with limited capacity of local
Utilization of UniMRCP client stack facilitates usage of remote
storage for recording and allows to use any MRCP compliant server,
which supports recorder resource such as UniMRCP server. Currently
only audio streams are supported, but hopefully video will be
supported either.
Moreover, set of synthesizer, recognizer and recorder resources allows
to build distributed and fully decomposed solutions, where telephony
applications may stay out of media processing, but do signaling.

Also sample recorder scenario has been added to umc application. To
use it update your local umcscenarios.xml file and input "run rec"
from console.

Arsen Chaloyan
The author of UniMRCP

UniMRCP 0.8.0 Released

UniMRCP 0.8.0 (r1199) has been released and now is available for download.

Source Distribution

Windows Installer

Windows SDK Installer

Dependency Packages (based on APR-1.3.8, APR-Util-1.3.9, Sofia-SIP-1.12.10)

This release introduces
- enhanced support for SDP offer/answer model,
- added support for flexible mapping of MRCP channels and media terminations,
- new alternate applications (asrclient, umc) based on the UniMRCP client stack

As always it also addresses issues reported by the community.

Changes since previous release 0.7.0 (r1064) include:

- Added an alternate arsclient application based on libunimrcpclient library (Philip)
- Added ability to limit max number of engine channels in use (Issue-11)
- Fixed interoperability with Cisco Gateway with the support of "mode" attribute in RTSP transport header (Sadeek Kheer)
- Added ability to get MRCP version of the channel from plugins (Vali)
- Added ability to configure custom, plugin dependent attributes from unimrcpserver.xml (Vali)
- Integrated "telephone-event" support into offer/answer
- Applied patch, which basically implements RFC4733/RFC2833 sender procedure (Chaitanya, Issue-31)
- Applied patch, which implements utility functions to transform DTMF characters and event identifiers (Vali, Issue-31)
- Fixed interoperability with GVP. The response to RTSP DESCRIBE request shouldn't contain RTSP Transport header (Vali, Issue-39).
- Fixed possible access violation in APT logger (Vali, Issue-40)
- Fixed trailing space in MRCPv2 response-line, interoperability with Optimsys (Roger)
- Reworked MPF context entity
- Supported multiple MPF transactions (sub-messages) compound in one message
- Fixed race condition issue in PocketSphinx plugin (Alban)
- Some MRCP servers "lie" about existing connections (Asackheim, Issue-41)
- Supported multiple "cmid" attributes per each control m-line
- Added MPF object derived entities such as mixer (n-sources, 1-sink) and multiplier (1-source, n-sinks)
- Test whether an engine opened successfully (Vali, Issue-42)
- Dropped any further requests from application if session is being terminated
- Separated user interface (what MRCP server uses) and implementation (what plugins implement) of MRCP engines.
- Introduced MRCP_PLUGIN_VERSION_DECLARE macro, which is required for the plugins
- Fixed C++ compile error in codec_descriptor.h (Vali, Issue-44)
- Provided better apr-iconv support in VC build (Vali, Issue-45)
- Fixed crash of client stack caused by race condition on session termination (Garmt, Adam, Issue-33)
- Implicitly modify initial offer (RTSP/MRCPv1), if it contains disabled media stream (Vali)
- Added a user level function to associate (de-associate) external object with the session (Randy)
- Fixed APR_ARRAY_IDX related issue in apt_pair (Anthony)
- Fixed plugin_version_hdr in configure.ac (John)
- Added new, configurable umc application based on libunimrcpclient library
- Added support for grammars supplied inline within RECOGNIZE request in PocketSphinx plugin (HuaJGuo, Issue-43)
- Sharing RTSP session among resources (Vali, Issue-46)
- Returned JB_DISCARD_TOO_EARLY if jitter buffer is full (Anthony)
- The RECOGNIZE message must only inherit the no redefined SET-PARAMS headers (Anthony, Issue-47)

Thanks for using UniMRCP.

Arsen Chaloyan
The author of UniMRCP

UniMRCP 0.7.0 Released

UniMRCP 0.7.0 (r1064) has been released and now is available for

Source Distribution

Windows Installer

Windows SDK Installer

Dependency Packages

This release fixes a few significant issues, which affect project usability under high load (stress testing).
It also introduces new ASR and TTS plugins based on open source PocketSphinx and Flite engines respectively.

Changes since previous release 0.6.0 (r930) include:
  • Using wakeable pollset in MRCPv2 server and client stacks
  • The terminate Remaining RTSP Sessions does not free all sessions (Anthony Masse, Issue-26)
  • Open log file in binary mode (Anthony Masse)
  • Allow trailing slash in RTSP URIs (V.Batrak)
  • Fixed crash while processing malformed SDP message
  • Failed to Find Channel errors (cpsoares, Issue-27)
  • Fixed the remaining issues related to message segmentation (Anthony Masse)
  • Fixed crash of client stack caused by race condition in mrcp-sofiasip module
  • Fixed potential crash of server stack (mrcp_session_destroy() should be called last)
  • Fixed potential crash of client stack (do not reference session object, since response to termination request has been sent)
  • Fixed conditial jump which depends on uninitialized value in mpf_decoder and mpf_encoder
  • Introduced wrappers around APR pool creators
  • Using rotation between multiple log files, instead of rollover in a single file (Anthony Masse)
  • Added LPCM codec as linear 16bit PCM codec in host order, while L16 is linear 16bit PCM codec in network order (Christopher Rienzo)
  • Added acinclude.m4 to allow autoreconf -i to work (Mike Jerris)
  • Fixed Mac OS X build (Mike Jerris)
  • Added PocketSphinx plugin
  • Added Flite plugin (Garmt)
  • Added the NOTICE file corresponding to the section 4 d of the Apache License (Jean-Michel Reghem)
  • RTP port management potential issues (cpsoares, Issue-34)
  • Decimal values in a mrcp_recog_header_t strangely rounded to the nearest tenth in the SET-PARAMS messages (Curatica, Issue-35)
  • Application freeze upon call to mrcp_client_shutdown (cpsoares, Issue-28)
  • Added basic NLSML document processor
  • Enhanced state machines to STOP in-progress SPEAK and RECOGNIZE requests on session termination
  • Stale MRCP sessions upon MRCP link disconnection (cpsoares, Issue-36)
  • Thread safe APR pools (cpsoares, Issue-29)

Thanks for using UniMRCP.
Arsen Chaloyan
The author of UniMRCP

Flite Plugin Available

I would like to announce the availability of Flite TTS plugin for UniMRCP server.
Special thanks goes to Garmt, who initially contributed and helped develop the plugin.

Currently supported TTS features are as follows:

English voices:
  • awb
  • kal
  • rms
  • slt
  • STOP
Synthesizer Speech Data:
  • text/plain

For the instructions on how to build and configure Flite with UniMRCP refer to

Please note, everything is working now, nevertheless this is basic availability only.
I have mostly tested the integrated solution in the following setup
SIPPhone -> FreeSWITCH/UniMRCPClient -> UniMRCPServer/Flite

Feedback is welcome.

Arsen Chaloyan
The author of UniMRCP

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