A-RTP Toolkit

Advanced RTP-RTCP Stack

Softil’s Advanced RTP/RTCP (Real-Time Transport Protocol/Real-Time Transport Control Protocol) Stack provides enhanced media transport functionality, including support for IMS, security and IPv6. The Advanced RTP/RTCP stack seamlessly scales from small, embedded platforms up to densely populated parallel processing environments.

Formerly Radvision Advanced RTP RTCP ToolKit, or A-RTP


Supports latest standards

Supports IETF RFC 3550, which replaces RFC 1889, delivering the most advanced RTP stack available on the market.

Integrated solution

Seamlessly works with other Softil Developer tools, such as the SIP, H.323, and MEGACO Toolkits and stacks and the Multimedia Terminal Framework Learn more on our products in Softil’s Developer Community.

Support for web deployments

Includes support for WebRTC Media, including DTLS Transport (RFC 6347) and support for DTLS / SRTP / SRTCP / ICE single port multiplexing (RFC 5761). For WebRTC applications is used as part of the WebRTC Interconnect Solution.

For developers of

  • IP phones and Media phones
  • Media servers
  • Webcams
  • MEGACO Gateways

Advanced RTP Stack Architecture

This Advanced RTP stack is a modular SDK in design and implementation. The extensive APIs and optional add-on modules offer application developers a large range of media related services.

The Advanced RTP stack is designed for high-end applications implemented in real-time, multi-threaded environments. It is written in ANSI C and is available on multiple operating systems through the use of Softil’s Common Core. The stack enables various run-time settings such as filters and bandwidth and provides both high level and low level/fine grain APIs to provide maximum flexibility. In addition, both asynchronous and synchronous operation modes are supported.


The stack consists of several modular and layered APIs as shown in the architecture diagram. The basic offering includes a large set of modules providing these key functions:
  • Full source code
  • Session management
  • Encryption and key management
  • RTCP events management
  • Version upgrades
  • Payloads support
  • NAT Traversal support
SRTP Add-on

The SRTP add-on implements RFC 3711, enabling confidentiality, message authentication and replay protection to the RTP traffic.

IMS & Media Control Add-on
The IMS and Media Control Add-on provides implementation of RFCs that are required by IMS and enable better control over media streams through extensions to RTCP. These include RFC 3611, which provides extended reports in RTCP and 4585, which adds a feedback mechanism within an RTP/RTCP session.
Adaptive Jitter Buffer Add-on
Softil’s Adaptive Jitter Buffer (AJB) Add-on is a standalone module that can be used with the Advanced RTP/RTCP stack or with any third-party RTP solutions. It is suitable for use with various types of media, including audio and video streams. The AJB module enables automatic collection of media packets into frames based on timestamps, and provides packet reordering by sequence numbers. In addition, duplicate packets are removed.


Advanced RTP Stack features:
  • ANSI C code
  • Thread-safe
  • IPv4/IPv6 support
  • Multiple stack instance per process space
  • Minimal memory copies
  • RTP header extension
  • Security and encryption profiles
  • Secure-RTP
  • Adaptive Jitter Buffer
  • Built-in codec payloads API for:
  • Voice: G.711, G.723.1, G.722, G.722.1, G.726, G.728, G.729A/B, iLBC, SIREN7/14, EVRC, SMV, AMR, AMR-WB
  • Video: MPEG-1, MPEG-2, MPEG-4, MJPEG, H.261, H.263, H.263+, H.264/AVC
  • DTMF and Far End Camera Control payloads
  • Payload APIs
  • UDP unicast and multicast support
  • Blocking and non-blocking operation modes
  • Synchronous and asynchronous operation modes
  • Logging services Statistics
  • Adaptive automatic RTCP report interval determination
  • Compound reports
  • Symmetric RTP
  • Support for STUN, ICE and other NAT traversal mechanisms
  • Manual APP and BYE messages
  • Extensible SSRC generation mechanism
Advanced RTP Comes with:
  • Full source code
  • Complete source code sample application
  • Full documentation, programmer’s guide and reference guide
  • Compiled binary of the IMS SIP stack
  • Porting guide (for unsupported operating systems)
  • Training
  • Version upgrades
  • Professional customer support
  • Turnkey solutions (upon request)
  • Porting services (upon request)


The Advanced RTP stack supports all of the latest standards required to build VoIP solutions. These include:
  • RFC 3550: Transport protocol for real-time applications
  • RFC 3551: RTP profile for audio and video conferences with minimal control
  • OMA PoC 1.0 compliant
  • ISMA 2.0 compliant
  • RFC 4571: Framing RTP and RTCP Packets over Connection-Oriented Transport
  • RFC 3711: Secured Real-time Transport Protocol (SRTP)
  • RFC 4585: RTCP-FB (AVPF) feedback mechanism
  • RFC 5124: SAVPF RFC 3611 – RTCP-XR extended reports
  • RFC 3556: RTCP bandwidth control
  • RFC 3640: MPEG-4 payload
  • RFC 3984: H.264/AVC payload
  • RFC 2429: H.263+ payload
  • RFC 2190 & 4629: H.263 payload
  • RFC 2032: H.261 payload
  • RFC 2435: MJPEG payload
  • RFC 2250: MPEG1/MPEG2 payloads
  • RFC 3267: AMR and AMR-WB payloads
  • RFC 3558 & RFC 4788: EVRC & SMV payloads
  • RFC 2833: DTMF payload
  • RFC 4573: FECC payload
  • RFC 3389: Comfort noise payload
  • RFC 4040: Transparent call payload H.460.19 – NAT traversal
  • RFC 7714: AES-GCM Authenticated Encryption in the Secure Real-time Transport Protocol (SRTP)

All Softil products and solutions address interoperability issues between disparate networks, protocols and devices. The Advanced RTP stack has been thoroughly tested for full interoperability with other clients and servers.

The Advanced RTP stack is based on Softil’s Common Core, an operating system abstraction layer specifically optimized for communication protocols and embedded platforms. This ensures easy portability of developed products between platforms and operating systems, including those not directly supported by Softil.

Softil Advanced RTP/RTCP Toolkit Data Sheet