SipMX Open Specifications

Bridging the gap between what the industry needs and what standards bodies deliver.

Sergio Ammirata, Ph.D.

The Story

Sergio Ammirata, Ph.D.

Co-founder of SipMX Creator of librist Chief Scientist, SipRadius Director, RIST Forum

With over 20 years in broadcast and streaming technology, Sergio has been at the forefront of defining how professional media travels over IP networks. As the creator of the librist library (the reference implementation of RIST) and an active participant in the IPMX working group, he has helped shape the standards that power modern contribution and production workflows.

His work spans multiple industry organizations: active participation in all five VSF working groups and the RIST Forum where he serves as a Director. This cross-organizational perspective informs the SipMX approach to specifications: practical solutions that work with existing standards, not against them.

VSF Working Group Participation: RIST (Reliable Internet Stream Transport) IPMX (Internet Protocol Media Experience) IPMX CODECs GCCG (Ground-Cloud-Cloud-Ground) TR-12 CDD (Cloud Device Discovery)

"Official specifications from standards bodies are valuable and necessary. But they're slow — often taking years to ratify — and sometimes shaped more by corporate politics than by what practitioners actually need in the field. Meanwhile, engineers are shipping products and solving real problems. SipMX publishes working specifications to bridge that gap: practical, tested, and ready to implement today. When the official standard catches up, we'll be the first to adopt it. Until then, the industry shouldn't have to wait."

— Sergio Ammirata, Ph.D.

Official Specifications We Support

SipMX implements the full NMOS specification suite from AMWA, plus key VSF technical recommendations.

AMWA NMOS Interface Specs

  • IS-04 Discovery & Registration
  • IS-05 Device Connection Management
  • IS-07 Event & Tally
  • IS-08 Audio Channel Mapping
  • IS-11 Stream Compatibility
  • IS-12 Control Protocol

AMWA Best Current Practices

  • BCP-002 Grouping & Asset Info
  • BCP-003 Secure Communication
  • BCP-004 Sender/Receiver Capabilities
  • BCP-008 Receiver Status Monitoring

VSF Technical Recommendations

  • TR-10-8 IPMX NMOS Requirements
  • TR-06 RIST (via librist / libsipmx_transport)
  • TR-06-4 RIST Decoder Synchronization

These specifications are defined and maintained by AMWA NMOS Specifications and VSF Technical Recommendations. SipMX participates in these standards bodies and implements the specifications as published.

New Specifications We're Writing

Filling the gaps in professional media workflows. All specifications are published in full — no secrets, no proprietary protocols.

SIPMX-IS-15 Implemented
Transport Security

WAN Transport for NMOS

Problem: NMOS requires inbound HTTP access to devices. Remote encoders behind firewalls, cloud nodes, and mobile units cannot accept inbound connections — NMOS simply doesn't work.
Solution: IS-15 defines MQTT and WebSocket transports for NMOS APIs. Devices initiate outbound connections to a broker, enabling full NMOS functionality without any inbound access.
  • MQTT pub/sub via broker (scalable)
  • WebSocket direct to gateway
  • Proxy registration with IS-04
  • Multi-gateway coordination
  • TLS 1.2+ security (BCP-003-01)
Read Full Specification
SIPMX-BCP-003-03-WAN Implemented
Security

WAN Certificate Provisioning

Problem: BCP-003-03 (EST) requires the server to reach the device. Devices behind NAT or firewalls cannot be reached — certificate provisioning fails.
Solution: Human-in-the-loop pairing with RFC 8628 user codes. Device initiates HTTPS, displays a short code, operator approves in UI, device receives certificate.
  • Device-initiated (firewall-friendly)
  • RFC 8628 user codes (WDJB-MJHT)
  • 15-minute code validity
  • Rate limiting and lockout
  • Integrates with IS-15 post-provisioning
Read Full Specification
SIPMX-BCP-003-03-PKA Implemented
Security

Public Key Authentication

Problem: Not all devices have manufacturer-issued certificates. Full EST enrollment is complex and heavy for some use cases.
Solution: JWK-based device authentication. Devices register a public key, admin approves via pairing code, device uses signed JWTs for authentication — no PKI required.
  • JSON Web Key (JWK) format
  • ECDSA P-256/P-384, EdDSA support
  • JWT access tokens
  • Rapid device onboarding
  • Platform-specific secure storage
Read Full Specification
SIPMX-BCP-007-01 Implemented
Transport

RIST Transport for NMOS

Problem: NMOS has no transport type for RIST contribution streams. IS-05 cannot manage RIST senders and receivers.
Solution: Defines urn:x-nmos:transport:rist and IS-05 transport parameters for RIST, including buffer size, encryption, authentication, and NAT traversal via relay.
  • Simple/Main/Advanced profiles
  • AES-128/256 encryption
  • EAP SHA256-SRP6a authentication
  • Caller/Listener modes + Relay
  • BCP-004 capability advertisement
Read Full Specification
SIPMX-BCP-007-02 Implemented
Transport

RIST Decoder Synchronization

Problem: RIST streams from different geographic locations arrive with varying latencies. Without synchronization, multi-camera switching shows visible timing errors.
Solution: NTP capture timestamps and adjustable sync buffers enable sub-frame alignment (<1ms) across streams from anywhere in the world. Based on VSF TR-06-4 Part 4.
  • VSF TR-06-4 Part 4 compliant
  • Sync Groups for coordinated playout
  • <1ms alignment accuracy
  • 100ms to 10 second delay range
  • Real-time drift monitoring
Read Full Specification
SIPMX-BCP-008-01 Implemented
Transport

Multi-Site Federation

Problem: IS-04 assumes a single registry per domain. Multi-site production, contribution networks, and disaster recovery need independent registries with selective sharing.
Solution: Federation of multiple NMOS registries with selective export/import of resources over MQTT. Sites maintain local autonomy while sharing specific streams.
  • Cloud and peer endpoint types
  • Selective resource export/import
  • Proxy registrations in local IS-04
  • Prefer direct, fallback to cloud
  • RIST data plane coordination
Read Full Specification
SIPMX-BCP-003-04 Implemented
Security

Device Approval and Conditional Registration

Problem: Standard IS-04 registries automatically make all registered devices visible to all controllers. This is unsuitable for multi-tenant and security-conscious environments.
Solution: Conditional registration with approval workflows. Devices register but remain pending until approved. Security metadata tracks registration source and trust indicators.
  • Three registry modes: Open, Compatible, Secure
  • Auto-approval rules (subnet, certificates)
  • Security metadata on all resources
  • Full audit trail of approvals
  • Backward compatible with IS-04 devices
Read Full Specification
SIPMX-BCP-009-01 Proposed
Transport

Gateway Discovery & Chained Routing

Problem: NMOS has no standard way to discover gateways, express input–output bindings, advertise conversion capabilities, or orchestrate multi-leg routes across transport boundaries.
Solution: Extends IS-04 Senders with ext_input_receiver_id to bind inputs to outputs, adds gateway capability advertisement on Devices, and defines a Chained Route model for multi-leg IS-05 connections through one or more gateways.
  • Transport bridging (RIST ↔ ST 2110 ↔ MXL)
  • Format conversion (transcode, scale, HDR→SDR)
  • Automatic gateway insertion by controller
  • Atomic multi-leg activation via IS-05 bulk
  • Federated gateway discovery across sites
Read Full Specification
Analysis Technical Analysis

Why Not VSF TR-12?

Question: VSF published TR-12 "Cloud Device Discovery" in 2026. Why didn't SipMX just adopt it instead of developing IS-15 and BCP-003-03-WAN?
Answer: TR-12 breaks VSF's tradition of building on existing standards. It ignores NMOS, uses AWS-specific tooling (Smithy), includes proprietary transports, and has no open source server implementation.
  • No NMOS integration whatsoever
  • AWS Smithy instead of OpenAPI/JSON Schema
  • Proprietary transports (SRT, Zixi)
  • No open source server implementation
  • Self-hosting requires building from scratch
Read Full Analysis

Proposed IPMX Codec Profiles

Draft proposals for extending IPMX to support HTJ2K and AV1 codecs, with corresponding NMOS integration specifications.

SIPMX-TR-10-15-Part2 Proposed
Codec

HTJ2K Codec Requirements

Purpose: Define requirements for High-Throughput JPEG 2000 (HTJ2K) in IPMX. HTJ2K provides ~10x faster encoding than traditional JPEG 2000 with royalty-free licensing.
Type: Mezzanine codec for TR-10-11 (Constant Bit-Rate) transport. Sub-frame latency (~33 lines), 1.25-4.0 bpp, compatible with JPEG 2000 ecosystem.
  • ISO/IEC 15444-15 compliant
  • RFC 9828 RTP payload format
  • Royalty-free licensing
  • Lossless transcoding to/from J2K-1
  • Resolution scalability built-in
Read Specification
SIPMX-BCP-006-03 Proposed
Codec

NMOS With HTJ2K

Purpose: Define how NMOS IS-04/IS-05 represent and manage HTJ2K streams. Media type: video/jp2
Scope: Flow attributes, Receiver capabilities (BCP-004-01), Sender capabilities (BCP-004-02), SDP requirements, and Controller compatibility checks.
  • HTJ2K-specific capability parameters
  • Bit rate and decomposition level signaling
  • Controller compatibility verification
  • SDP examples for RFC 9828
  • Parameter registration proposals
Read Specification
SIPMX-TR-10-17 Proposed
Codec

AV1 Codec Requirements

Purpose: Define requirements for AV1 in IPMX. AV1 provides 30-50% better compression than HEVC with royalty-free licensing from AOMedia.
Type: Delivery codec for TR-10-7 (Variable Bit-Rate) transport. Ideal for WAN contribution, WiFi distribution, and multi-viewer feeds.
  • AOMedia AV1 Bitstream compliant
  • AOMedia RTP Payload Format
  • Royalty-free licensing
  • Native temporal/spatial SVC
  • Hardware support growing
Read Specification
SIPMX-BCP-006-04 Proposed
Codec

NMOS With AV1

Purpose: Define how NMOS IS-04/IS-05 represent and manage AV1 streams. Media type: video/AV1
Scope: Flow attributes, scalability representation (single stream SVC and simulcast), Receiver capabilities, and Controller compatibility checks.
  • AV1 profile/level/tier signaling
  • Scalability mode support (L1T3, L2T2, etc.)
  • Simulcast representation in NMOS
  • Dependency Descriptor RTP extension
  • Hardware decoder capability signaling
Read Specification

Draft Status: These specifications are draft proposals published for community review and feedback prior to formal submission.

  • AMWA candidates: IS-15, BCP-003-03-WAN, BCP-003-03-PKA, BCP-003-04, BCP-006-03, BCP-006-04, BCP-007-01, BCP-008-01, BCP-009-01
  • VSF candidates: TR-10-15 Part 2 (HTJ2K), TR-10-17 (AV1), BCP-007-02 (extends TR-06-4)

Security Through Transparency

"Security by obscurity is a recipe for failure. The only systems that can be trusted are those that have been scrutinized, tested, and validated by the community. We publish every specification in full and open-source the implementations that matter most."

librist

C

The reference implementation of RIST (Reliable Internet Stream Transport). Created and maintained by Sergio Ammirata, librist implements VSF TR-06-1/2/3 and is the foundation for RIST support in major media applications worldwide. The upstream project that libsipmx_transport builds upon.

Adopted by: FFmpeg OBS Studio GStreamer VLC Nimble Streamer

Production-proven in thousands of deployments across broadcast, streaming, and contribution workflows.

View on code.videolan.org

libsipmx_transport

C

The successor to librist for SipMX products. A unified reliable media transport library providing both RIST and SRT protocol engines over a shared infrastructure layer. Extends librist with decoder synchronization, satellite redundancy, content selection, and a clean-room SRT engine.

Extends librist with:
  • VSF TR-06-4 Part 4 — Decoder Synchronization (<1ms sync)
  • VSF TR-06-4 Parts 6 & 7 — Content Selection & Satellite Redundancy
  • SatHybrid — Satellite/terrestrial redundant delivery
  • Clean-room SRT engine (draft-sharabayko-srt)
  • Unified crypto, event loop, and UDP I/O for both protocols

Powers SipMX Gateway and DeviceSDK transport. LGPL-3.0 licensed. No external runtime dependencies.

Request Source Access

SipmxCore.Nucleus

C#

The shared core library that powers both SipMX Core (Server) and SipMX DeviceSDK. Contains all NMOS models, security utilities (PKA, EST), IS-15 types, and common infrastructure. The exact same code runs in both products — no hidden differences.

Contains:
  • NMOS Models (IS-04/05/07/08/11/12/15)
  • PKA Implementation (JWK registry, token issuance)
  • Certificate utilities (BCP-003-03)
  • Federation protocol types (BCP-008-01)
  • Device Approval workflow (BCP-003-04)
  • RIST transport models (BCP-007-01)
  • RIST Decoder Sync (BCP-007-02)
  • HTJ2K codec models (TR-10-15 Part 2, BCP-006-03)
  • AV1 codec models (TR-10-17, BCP-006-04)
  • Gateway Discovery & Chained Routing (BCP-009-01)

Enables third parties to build compatible implementations with identical protocol behavior.

Request Source Access

Why Open?

Interoperability

Published specifications enable any vendor to implement compatible products. No vendor lock-in, no secret handshakes.

Security

Open implementations can be audited by security researchers. Vulnerabilities are found and fixed faster.

Trust

When you can read the spec and the code, you know exactly what the product does. No surprises.

Longevity

Open specifications don't die with companies. The broadcast industry needs standards that outlast any single vendor.

Ready to implement?

Read the specifications, explore the DeviceSDK, or join the discussion.

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