BBC R&D Hosts EBU Interoperability Test Event
Last week BBC R&D hosted an EBU/VCIP interoperability test event for a new industry standard called SMPTE 2022-5/6. This is a standard that primarily targets uncompressed video contribution and distribution over general-purpose networks. It enables SDI video to travel uncompressed over IP networks, which is especially of interest to BBC R&D because the department’s long term vision is that IP will replace traditional broadcast-specific technologies. There are some challenges in this long term vision, but these are often outweighed by the benefits that can be achieved in cost, flexibility and functionality.
The work to make the SMPTE 2022-5/6 standard began within the VSF and was standardised by SMPTE in 2012. The two parts of the standard are as follows:
- SMPTE 2022-5: the Forward Error Correction scheme to be applied to the media.
- SMPTE 2022-6: the media encapsulation within RTP.
The purpose of interoperability tests like this is to get several manufacturers together to test that their products work with one another. This is necessary because when implementing complex industry standards there are often subtle misinterpretations of the standard between manufacturers that result in products not being interoperable, which defeats the point in having a standard in the first place. Therefore interoperability tests are useful to ensure all manufacturers have a common understanding and implementation of the standard – something that is clearly a benefit to broadcasters like the BBC.
The EBU interoperability tests for SMPTE 2022-5/6 checked the compatibility between manufacturers for a number of features (including the correct transport of subtitles, video payload identifier, active format descriptor, timecode, multi-channel audio metadata and embedded audio carriage). Each of these features was tested for compatibility in three media formats:
- SD: 576i25 (270Mbps)
- HD: 1080i25 (1.5Gbps)
- 3G: 1080p50 (3Gbps)
The compliance of these features was recorded as well as other measurements including the end-to-end latency and stability. Network impairments were also added to be sure that the Forward Error Correction was working as designed.
Industry standards that ensure the interoperability of equipment are particularly important to the BBC because they enable the choice of the best product at any point in time, knowing that it will work with existing equipment. Using standards-based equipment means that the BBC should not get itself into a situation where it can only buy compatible equipment from one supplier, and this helps to ensure that equipment can be purchased at competitive rates.
The results of the interoperability test were generally positive for such a new standard. The SMPTE 2022-6 (media encapsulation) standard was found to be fully interoperable between the manufacturers who participated in the test and some useful measurements were obtained around this. However, the SMPTE 2022-5 (Forward Error Correction) was only found to be partially interoperable, especially for the edge case matrix sizes that were tested. The manufacturers will continue correcting the interoperability issues that were identified as well as implementing new functionality that would be required for broadcasters, like the BBC, to start using this equipment.
We would like to thank Yuan-Xing Zheng from the BBC Technology Strategy & Architecture Team, who organised the event from the BBC side, and Adi Kouadio from the EBU, who was responsible for the overall project management. We would also like to thank all the manufacturers who contributed and participated for making this such a successful interoperability test.