How to Explain ST2110 to a Six Year Old

Presenters : Kieran Kunhya - OBS

Year : 2022

dlp_document_download : How to Explain ST 2110 to a Six-Ye a r-Old Kieran Kunhya, Open Broadcast Systems §Company specialisingin software-based encoders and decoders for Sport, News and Channel contribution (B2B)§Based in Central London§Build everything in house§Hardware, firmware, software§Not to be confused with:Company Introduction What is ST 2110"If you can't explain it to a six year old, you don't understand it yourself."§Never seen any webinars/papers etc. get close to a half-decent explanation§Way too detailed or way too handwavy§Often very full of jargon§No explanation of why things are being done§Let’s simplify years of work into 15 minutes! Where things are§Live production (sports, news etc.) uses Serial Digital Interface cables§Old fashioned Electrical Signal transmitting what was a very large amount of data when it was invented (gigabit/s). Nowadays not so much. §One TV signal (pictures + sound) in one cable§And other historical signals§Expensive equipment to switch between signals§Specific to the television industry, huge mess of cabling Where things are§Don’t want to use old-fashioned cabling§Internet growing very quickly§Yo u t u b e, Netflix, Social Media, Big Data§We can use Internet technology (but not the internet itself) to send pictures and sound around a facility. Known as Internet Protocol "IP" technology.§Chop up a television picture and sounds into thousands of little pieces ("packets") and send over a wired network§Hundreds of television signals in a cable. Cheaper equipment from much bigger industry About Time (1)§Set the time of two clocks and check them after a day§For example a microwave and an oven§They won’t be the same§Clocks have their own time source inside that have small differences§Could be dependent on heat, location (e.galtitude), manufacturer of the clock§Nowadays, phone connects to the Internet to set its time About Time (2)§Television pictures and sound are generated from a clock on the camera or microphone. In Europe, 25 still pictures a second§Hard to cut between two camera angles if the clocks do not match12 About Time (3)§An old fashioned signal to keep them together, yet another cable§Note: on the web, Zoom, webcasts etc., don’t do this12 About Time (4)§During a leap year an extra day is added because the Earth doesn’t perfectly go round the Sun (365.2422 days)§Also small adjustments known as "leap seconds" at certain times when the clock strikes New Year’s §Need to make sure time doesn’t jump otherwise pictures will glitch when Big Ben strikes midnight§One of the reasons we can’t just use the time sync mechanism like a phone§Use GPS (satellite navigation) as a time-source, very high quality, has no leap seconds§Transport this as IP Packets over the Network (Precision Time Protocol –PTP) but much better quality than a normal Internet connected clock Packets and time (1)§Split the pictures and sound up into thousands of little packets§Imagine all television signals started at the same time, and each picture was a "tick"§Work how many pictures there should be by now and wait to start at the right time1stJanuary 1970(PTP epoch)42 years later…Now Packets and time (2)§Lots of pictures and sounds, split into packets and being sent over the network§Packets given an address (can send to more than one place) –millions per second§Not everyone needs to receive pictures if they are only using the sound§When I receive these packets, how do I know when they are from?§Need to know this so I can make sure they are in sync (when he kicks the ball you get a kicking sound at the right time)§Attach the time ("timestamp") to each packet so we can put the puzzle back together Key points§We want to use modern IP technology to make live television§We have agreed on a common time across all the clocks in the broadcast§We split pictures and sound up into thousands of packets and make sure we send them at the right time, and add a timestamp to each packets§Anyone who wants to receive these packets uses the timestamps to put them all back together§The rest is just jargon, and implementation details Any Questions?Kieran