Ground to Cloud is a handy way to say ‘getting things into the public cloud’. Whether you’re using AWS, Oracle or another cloud provider, you need to get your data there and since that’s called sending to the cloud, anything that’s not the cloud is…the ground. Within broadcast, files aren’t too tricky to get into the cloud, even if the big ones still take a while to send. Live video, audio and media essences provide more of a challenge. This is an overview of why ground to cloud isn’t trivial.
Packet loss
You’re guaranteed to lose some data sooner or later, so it’s important to protect against it. Full-on redundancy can be achieved by sending everything twice using SMPTE 2022-7. A less data-intensive option is old-school FEC but state of the art would be using a dynamic protocol such as RIST or SRT that can up the data sent to compensate for losses, but throttle back when there’s plain sailing.
PTP and timing
If you want to go as far as sending uncompressed video or audio into the cloud, you may find you need to extend your PTP clock. This needs to be done carefully and only if absolutely necessary.
Keeping it together
If you’re sending essences from the same content separately you can use timestamps to keep them synchronised, but when delivering multiple streams of content, it’s important to keep their relative latency constant and preferably zero. This means making sure that they don’t take different paths on their journey.
Controlling Bandwidth
As most people don’t want to send all 1Gbps of uncompressed video into the cloud, compression options are needed to keep bandwidth usage under control. Typically JPEG XS is considered for high-quality links, but MPEG-based codecs can be used instead.
Latency management
Live video deserves to be delivered quickly and whilst there is a limitation on the speed that light can travel in fibres, we owe it to the viewers to keep protocol delays minimal too. This means using the minimum buffer sizes, choosing the compression options appropriately and optimising the encoding time.
Bidirectionality
For some types of links, such as those for a PTZ camera, a return data link is required for control.
Security
Many providers require encryption for their feeds whereby the essences are encrypted. Authentication is typically dealt with separately. DTLS, a UDP-based derivative of the web’s TLS encryption scheme for HTTP, can be used for this in lieu of a pre-shared password.