Strict CBR and DVB compliant video over 4G and 5G bonded networks

4G and 5G bonding for broadcast contribution is coming of age as mobile networks get faster and faster. For many years there have been cellular bonding products, mainly based around “backpack-style” solutions that have revolutionised newsgathering and mobile journalism. However, with the advancement of 4G and 5G networks, these backpack solutions have found applications in sports and other broadcast contribution feeds, often without an appreciation for the distinct requirements of such transmissions compared to newsgathering.

Enter the necessity for broadcast-grade encoders like the OBE C-100 Encoder. These encoders adhere to the stringent constant bitrate (CBR) and DVB transport stream standards essential for high-end broadcast transmissions, particularly in sports. It’s crucial to recognise that while certain products may boast support for protocols like SRT, SRT merely serves as an envelope around a transport stream. The underlying transport stream within SRT may lack the necessary compliance for seamless interoperability with professional receivers.

The details

Let’s dig into the details. Sports events are often sent to numerous territories via numerous intermediary service providers and so it’s vitally important that the dozens of professional receivers are able to decode a feed smoothly and reliably. On the other hand, a newsfeed is often going between a remote location and a single news channel, both using the same vendor on each end so there is no need to comply with anything. It’s not practical in major sports or other linear transmissions for everyone to have a single-vendor piece of equipment.

The two graphs above show real world data from an OBE C-100 Encoder and a cellular bonding backpack operating on the same wired network. It is clear the cellular bonded backpack is unable to maintain strict CBR. Note that this isn’t the network that is causing these changes in bit rate, it’s the device itself not outputting data smoothly but instead bursting data, slowing down and then bursting data again. The stream from the backpack is unable to be decoded on many professional receivers, producing a black screen. It certainly is not suitable for transmission onto satellite or other systems requiring strict compliance. The SDI output of the cellular bonding solution would have to be re-encoded again to be CBR, adding latency and reducing quality.

We’ve been working with our partners at Zixi for several years with low-latency bonded cellular with strict transport streams in the real world with many customers using 4G and 5G transmissions on a daily basis. Working with Zixi, we have done several world firsts in the field of 5G transmissions. We have many more announcements to make in this area. Stay tuned!

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