AES67

Video: A Review of the IP Live Core Implementation in BBC Cymru Wales

Posted on by Russell Trafford-Jones

Whenever there’s a step change in technology, we need early adopters and moving to SMPTE’s ST 2110 is no exception. Not only do early adopters help show that the path ahead is good, but they often do a lot to beat down the bushes and make the path easier to pass for all that follow. For larger companies whose tech refresh or building move comes at a time when the industry is facing a major technology change, there comes a time when whilst the ground may not be firm ahead, the company can’t justify investing in technology that would soon be out of date or in technology which won’t support the needs of the company in several years’ time. This is just the situation that BBC Cymru Wales found themselves in when it was time to move out of their old property into a purpose-built national HQ in the heart of Cardiff.

In this video from the IP Showcase, Mark Patrick and Dan Ashcroft guide us through ‘whys’ and the ‘hows’ of the relocation project. It’s important to remember that this project was long in the making with the decision on location taking place in 2014 with the technology decisions taking place in 2016 and 2017. The project took an open approach to the IP/SDI question and asked for RFP responses to include a fully-SDI and a fully-IP option. It was clear during the selection process that IP was the way to go not because the solution was cheaper in the short term, but because it was much more future-proof and the costs would come down over time giving a much better total cost of ownership. Don’t forget that the initial costs of HD video equipment were much higher than those now. For more on the pros and cons of SDI, watch ‘Is IP really better than SDI?‘ by Ed Calverly.

 

 

Mark and Dan talk through the thinking for the IP choice and their decision to pick a vendor who would be their partner in the project. The theory being that given the standards were still very young, it would be important to work closely to ensure success. In addition to Grass Valley equipment, they chose a Cisco network with Cisco SDN control and operational control by BNCS. The talk references architectures we’ve featured on The Broadcast Knowledge before with Arista’s Gerard Phillips discussing the dual-network spine-leaf architecture chosen and noting the difficulty they had incorporating the Dante network into the 2110 infrastructure and their choice of a third network purely for control traffic.

We often hear about the importance of PTP in a SMPTE ST 2110 network for live production because it is vital to keep all the essences in sync. For more information about the basics of ST 2110 check out this talk by Wes Simpson. PTP is both simple and complex so Mark explains how they’ve approached distributing PTP ensuring that the separate networks, amber and blue, can share PTP grandmasters for resilience.

Other topics covered in the talk include

  • Control Methodology
  • AES67 and Dante
  • Testing equipment
  • JT-NM interoperability testing
  • Successes and difficulties

Watch now!
Speakers

Mark Patrick Mark Patrick
Lead Architect,
BBC
Dan Ashcroft Dan Ashcroft
Senior Project Manager,
BBC
Wes Simpson Moderator: Wes Simpson
LearnIPVideo.com

Video: AES67 Over Wide Area Networks

Posted on by Russell Trafford-Jones


AES67 is a widely adopted standard for moving PCM audio from place to place. Being a standard, it’s ideal for connecting equipment together from different vendors and delivers almost zero latency, lossless audio from place to place. This video looks at use cases for moving AES from its traditional home on a company’s LAN to the WAN.

Discovery’s Eurosport Technology Transformation (ETT) project is a great example of the compelling use case for moving to operations over the WAN. Eurosport’s Olivier Chambin explains that the idea behind the project is to centralise all the processing technology needed for their productions spread across Europe feeding their 60 playout channels.

Control surfaces and some interface equipment is still necessary in the European production offices and commentary points throughout Europe, but the processing is done in two data centres, one in the Netherlands, the other in the UK. This means audio does need to travel between countries over Discovery’s dual MPLS WAN using IGMPv3 multicast with SSM

From a video perspective, the ETT project has adopted 2110 for all essences with NMOS control. Over the WAN, video is sent as JPEG XS but all audio links are 2022-7 2110-30 with well over 10,000 audio streams in total. Timing is done using PTP aware switches with local GNSS-derived PTP with a unicast-over-WAN as a fallback. For more on PTP over WAN have a look at this RTS webinar and this update from Meinberg’s Daniel Boldt.

 

 

Bolstering the push for standards such as AES67 is self-confessed ‘audioholic’ Anthony P. Kuzub from Canada’s CBC. Chair of the local AES section he makes the point that broadcast workflows have long used AES standards to ensure vendor interoperability from microphones to analogue connectors, from grounding to MADI (AES10). This is why AES67 is important as it will ensure that the next generation of equipment can also interoperate.

Surrounding these two case studies is a presentation from Nicolas Sturmel all about the AES SC-02-12-M working group which aims to define the best ways of working to enable easy use of AES67 on the WAN. The key issue here is that AES67 was written expecting short links on a private network that you can completely control. Moving to a WAN or the internet with long-distance links on which your bandwidth or choice of protocols is limited can make AES67 perform badly if you don’t follow the best practices.

To start with, Nicolas urges anyone to check they actually need AES67 over the WAN to start with. Only if you need precise timing (for lip-sync for example) with PCM quality and low latencies from 250ms down to as a little as 5 milliseconds do you really need AES67 instead of using other protocols such as ACIP, he explains. The problem being that any ping on the internet, even to something fairly close, can easily take 16 to 40ms for the round trip. This means you’re guaranteed 8ms of delay, but any one packet could be as late as 20ms known as the Packet Delay Variation (PDV).

Not only do we need to find a way to transmit AES67, but also PTP. The Precise Time Protocol has ways of coping for jitter and delay, but these don’t work well on WAN links whether the delay in one direction may be different to the delay for a packet in the other direction. PTP also isn’t built to deal with the higher delay and jitter involved. PTP over WAN can be done and is a way to deliver a service but using a GPS receiver at each location, as Eurosport does, is a much better solution only hampered by cost and one’s ability to see enough of the sky.

The internet can lose packets. Given a few hours, the internet will nearly always lose packets. To get around this problem, Nicolas looks at using FEC whereby you are constantly sending redundant data. FEC can send up to around 25% extra data so that if any is lost, the extra information sent can be leveraged to determine the lost values and reconstruct the stream. Whilst this is a solid approach, computing the FEC adds delay and the extra data being constantly sent adds a fixed uplift on your bandwidth need. For circuits that have very few issues, this can seem wasteful but having a fixed percentage can also be advantageous for circuits where a predictable bitrate is much more important. Nicolas also highlights that RIST, SRT or ST 2022-7 are other methods that can also work well. He talks about these longer in his talk with Andreas Hildrebrand

The video concludes with a Q&A.

Watch now!
Speakers

Nicolas Sturmel Nicolas Sturmel
Product Manager – Senior Technologist,
Merging Technologies
Anthony P. Kuzub Anthony P. Kuzub
Senior Systems Designer,
CBC/Radio Canada
Olivier Chambin Olivier Chambin
Audio Broadcast Engineer, AioP and Voice-over-IP
Eurosport Discovery

Video: AES67 Beyond the LAN

Posted on by Russell Trafford-Jones

It can be tempting to treat a good quality WAN connection like a LAN. But even if it has a low ping time and doesn’t drop packets, when it comes to professional audio like AES67, you can help but unconver the differences. AES67 was designed for tranmission over short distances meaning extremely low latency and low jitter. However, there are ways to deal with this.

Nicolas Sturmel from Merging Technologies is working as part of the AES SC-02-12M working group which has been defining the best ways of working to enable easy use of AES67 on the WAN wince the summer. The aims of the group are to define what you should expect to work with AES67, how you can improve your network connection and give guidance to manufacturers on further features needed.

WANs come in a number of flavours, a fully controlled WAN like many larger broadacsters have which is fully controlled by them. Other WANs are operated on SLA by third parties which can provide less control but may present a reduced operating cost. The lowest cost is the internet.

He starts by outlining the fact that AES67 was written to expect short links on a private network that you can completely control which causes problems when using the WAN/internet with long-distance links on which your bandwidth or choice of protocols can be limited. If you’re contributing into the cloud, then you have an extra layer of complication on top of the WAN. Virtualised computers can offer another place where jitter and uncertain timing can enter.

Link

The good news is that you may not need to use AES67 over the WAN. If you need precise timing (for lip-sync for example) with PCM quality and low latencies from 250ms down to as a little as 5 milliseconds do you really need AES67 instead of using other protocols such as ACIP, he explains. The problem being that any ping on the internet, even to something fairly close, can easily have a varying round trip time of, say, 16 to 40ms. This means you’re guaranteed 8ms of delay, but any one packet could be as late as 20ms. This variation in timing is known as the Packet Delay Variation (PDV).

Not only do we need to find a way to transmit AES67, but also PTP. The Precise Time Protocol has ways of coping for jitter and delay, but these don’t work well on WAN links whether the delay in one direction may be different to the delay for a packet in the other direction. PTP also isn’t built to deal with the higher delay and jitter involved. PTP over WAN can be done and is a way to deliver a service but using a GPS receiver at each location is a much better solution only hampered by cost and one’s ability to see enough of the sky.

The internet can lose packets. Given a few hours, the internet will nearly always lose packets. To get around this problem, Nicolas looks at using FEC whereby you are constantly sending redundant data. FEC can send up to around 25% extra data so that if any is lost, the extra information sent can be leveraged to determine the lost values and reconstruct the stream. Whilst this is a solid approach, computing the FEC adds delay and the extra data being constantly sent adds a fixed uplift on your bandwidth need. For circuits that have very few issues, this can seem wasteful but having a fixed percentage can also be advantageous for circuits where a predictable bitrate is much more important. Nicolas also highlights that RIST, SRT or ST 2022-7 are other methods that can also work well. He talks about these longer in his talk with Andreas Hildrebrand

Nocals finishes by summarising that your solution will need to be sent over unicast IP, possibly in a tunnel, each end locked to a GNSS, high buffers to cope with jitter and, perhaps most importantly, the output of a workflow analysis to find out which tools you need to deploy to meet your actual needs.

Watch now!
Speaker

Nicolas Sturmel Nicolas Sturmel
Network Specialist,
Merging Technologies

Video: AES67/ST 2110-30 over WAN

Posted on by Russell Trafford-Jones

Dealing with professional audio, it’s difficult to escape AES67 particularly as it’s embedded within the SMPTE ST 2110-30 standard. Now, with remote workflows prevalent, moving AES67 over the internet/WAN is needed more and more. This talk brings the good news that it’s certainly possible, but not without some challenges.

Speaking at the SMPTE technical conference, Nicolas Sturmel from Merging Technologies outlines the work being done within the AES SC-02-12M working group to define the best ways of working to enable easy use of AES67 on the WAn. He starts by outlining the fact that AES67 was written to expect short links on a private network that you can completely control which causes problems when using the WAN/internet with long-distance links on which your bandwidth or choice of protocols can be limited.

To start with, Nicolas urges anyone to check they actually need AES67 over the WAN to start with. Only if you need precise timing (for lip-sync for example) with PCM quality and low latencies from 250ms down to as a little as 5 milliseconds do you really need AES67 instead of using other protocols such as ACIP, he explains. The problem being that any ping on the internet, even to something fairly close, can easily take 16 to 40ms for the round trip. This means you’re guaranteed 8ms of delay, but any one packet could be as late as 20ms known as the Packet Delay Variation (PDV).

Link

Not only do we need to find a way to transmit AES67, but also PTP. The Precise Time Protocol has ways of coping for jitter and delay, but these don’t work well on WAN links whether the delay in one direction may be different to the delay for a packet in the other direction. PTP also isn’t built to deal with the higher delay and jitter involved. PTP over WAN can be done and is a way to deliver a service but using a GPS receiver at each location is a much better solution only hampered by cost and one’s ability to see enough of the sky.

The internet can lose packets. Given a few hours, the internet will nearly always lose packets. To get around this problem, Nicolas looks at using FEC whereby you are constantly sending redundant data. FEC can send up to around 25% extra data so that if any is lost, the extra information sent can be leveraged to determine the lost values and reconstruct the stream. Whilst this is a solid approach, computing the FEC adds delay and the extra data being constantly sent adds a fixed uplift on your bandwidth need. For circuits that have very few issues, this can seem wasteful but having a fixed percentage can also be advantageous for circuits where a predictable bitrate is much more important. Nicolas also highlights that RIST, SRT or ST 2022-7 are other methods that can also work well. He talks about these longer in his talk with Andreas Hildrebrand

Watch now!
Speaker

Nicolas Sturmel Nicolas Sturmel
Product Manager, Senior Technologist,
Merging Technologies