Video: Adaptive Bit Rate video delivery (MPEG-DASH)

MPEG-DASH has been in increasing use for many years and while the implementations and versions continue to improve and add new features, the core of its function remains the same and is the topic of this talk.

For anyone looking for an introduction to multi-bitrate streaming, this talk from Thomas Kernen is a great start as he charts the way streaming has progressed from the initial ‘HTTP progressive download’ to dynamic streaming which adapts to your bandwidth constraints.

Thomas explains the way that players and servers talk and deliver files and summarises the end-to-end distribution ecosystem. He covers the fact that MPEG DASH standardises the container description information, captioning and other aspects. DRM is available through the common encryption scheme.

MPD files, the manifest text files, which are the core of MPEG-DASH are next under the spotlight. Thomas talks us through the difference between Media Presentations, Periods, Representations and Segment Info. We then look at the ability to use the ISO BMFF format or MPEG-2 TS like HLS.

The DASH Industry Forum, DASH-IF, is an organisation which promotes the use of DASH within businesses which means that not only do they do work in spreading the word of what DASH is and how it can be helpful, but they also support interoperability. DASH264 is also the output from the DASH-IF and Thomas describes how this specification of using DASH helps with interoperability.

Buffer bloat is still an issue today which is a phenomenon where for certain types of traffic, the buffers upstream and locally in someone’s network can become perpetually full resulting in increased latency in a stream and potentially instability. Thomas looks briefly at this before moving on to HEVC.

At the time of this talk, HEVC was still new and much has happened to it since. This part of the talk gives a good introduction to the reasons that HEVC was brought into being and serves as an interesting comparison for the reasons that VVC, AV1, EVC and other codecs today are needed.

For the latest on DASH, check out the videos in the list of related posts below.

Watch now!

Thomas Kernen Thomas Kernen
Staff Software Architect, Mellanox
Co-Chair SMPTE 32M Technology Committee, SMPTE
Formerly Technical Leader, Cisco,

Video: Avoiding Traps and Pitfalls When Designing SMPTE 2059-2 Networks

As the industry gains more and more experience in implementing PTP, AKA SMPTE 2059-2, timing systems it’s natural to share the experiences so we can all find the best way to get the job done.

Thomas Kernen is a staff architect at Mellanox with plenty of experience under his belt regarding PTP so he’s come to the IP Showcase at IBC 2019 to explain.

The talk starts by discussing what good timing actually is and acknowledging everyone’s enthusiasm going into a project for a well designed, fully functioning system. But, importantly, Thomas then looks at a number of real-world restrictions that come into projects which compromise our ability to deliver a perfect system.

Next Thomas looks at aspects of a timing strategy to be careful of. The timing strategy outlines how the timing of your system is going to work, whether that is message rates or managing hierarchy amongst many other possibilities.

The network design itself, of course, has an important impact on your system. This starts at the basics of whether you build a network which is, itself, PTP aware. In general, Thomas says, it should be PTP aware. However, for smaller networks, it may be practical to use without.

Security gets examined next, talking about using encrypted transports, access control lists, ensuring protect interfaces etc. with the aim of preventing unintended access, removing the ability to access physically – much of this is standard IT security, but it’s so often ignored that it’s important to point it out.

PTP is a system, it’s not a signal like B&B so monitoring is important. How will you know the health of your PTP distribution? You need to monitor on the network side, from the point of view of the deices themselves but also analyse the timing signals themselves, for instance, by comparing the timing signals between the main and reserve.

Finally, Thomas warns about designing redundancy systems since “Redundancy in PTP doesn’t exist.” and then finishes with some notes on properly completing a PTP project.

Watch now!


Thomas Kernen Thomas Kernen
Staff Architect,
Mellanox Technologies

Video: Enhanced Redundancy of ST 2059-2 Time Transfer over ST 2022-7 Redundant Networks

We’re all starting to get the hang of the basics: that PTP is the new Black and Burst, that we still need sync to make studios work and that PTP (IEEE1588) is standardised under ST 2059 for use in the broadcast industry. So given its importance, how can we make it redundant?

Thomas Kernen from Mellanox and Chair within the STMPE standards community takes about his real-lift work on implementing PTP with an eye on redundancy methods

Thomas covers the following and more:

  • Whether 2022-7 works for PTP
  • BMCA Redundancy Model
  • Multiple Grand master use
  • Adjusting to dynamic variations in timing feeds
  • IEEE 1588 v2.1
  • Timing Differences in basic networks


Thomas Kernen Thomas Kernen
Staff Software Architect, Mellanox Technologies
Co-chair SMPTE 32NF Network Facilities Technology Committee