AV-over-IP Evolution: Pivotal Papers Charting the Course for Internet Protocol Media Transmission
In a recent project, a company embarked on an ambitious upgrade of its audio-visual (AV) system, with a focus on integrating modern technology while maintaining compatibility with existing equipment. The heart of this transformation was the adoption of the Interoperable Master Format Extended (IPMX) standard, a groundbreaking solution in the AV-over-IP space.
The digital signage system in the project, partly upgraded, retains older monitors that are not slated for replacement. This has led to an EDID-related headache, as the older monitors only support 4K30, as confirmed by the NMOS controller's EDID endpoint. To address this issue, the IPMX receiver's Link Offset Delay was employed to compensate for the inaccurate values given to the IPMX sender by the HDMI switch.
In the break room, an IPMX solution capable of handling content mixing while adhering to High-bandwidth Digital Content Protection (HDCP) through the HKEP protocol was utilised. However, an HDMI switch in the same room was sending out strange audio info frames with large values in the LATENCY field, causing sync issues. To debug this problem, a quick search of the interwebs revealed Wireshark dissectors for HKEP and IPMX RTCP sender reports.
The 'secure' huddle room required all content traffic to be encrypted, introducing the use of the Privacy Encryption Protocol (PEP) in the project. NMOS IS-12, on the other hand, enabled direct adjustment of settings for scaling and frame rate conversion through the controller, potentially solving compatibility issues.
The auditorium portion of the project required Precision Time Protocol (PTP) due to the use of AES67, which doesn't support asynchronous sources and requires PTP. IPMX, being a comprehensive, interoperable standard for AV-over-IP solutions, built on the foundations of SMPTE ST 2110 and AES67, was well-suited to handle these requirements.
The customer had a specific request for the new panel: they wanted it to display a mix of digital signage and over-the-air content, with company announcements shown in an "L-bar" around the side and bottom of the display. IPMX devices can receive both SMPTE ST 2110 and AES67 content, simplifying the connection of asynchronous AV sources into synchronous live production systems, making this request achievable.
The development of IPMX is rooted in the Video Services Forum (VSF) TR-10 and Advanced Media Workflow Association (AMWA) NMOS specifications. As IPMX moves into its final testing phase this year, it promises to deliver capabilities unprecedented in the AV-over-IP space, providing seamless integration and interoperability between baseband AV and IP networks, enhancing system interoperability and configuration in professional AV setups.
