Musings on the digital age
From Broadcast Engineering come these interesting observations. (external link) Read the article before they pull it down. We're going back to circuit switching?! (internal link) After I thought everything was going to packet switching, done over all IP networks? Hmm. And note the word essence. An essence stream. Fairly flowery language for engineers:
"Program elements in the broadcast domain are continuous signals in real time. IT in broadcasting deals with compressed media files transferred at greater than real time rates. Continuous essence streams do not require buffering."
"Gigabit means one billion bits per second. In the IT realm, this is a theoretical number where the number may or may not specify a certain bandwidth. What transfer rate really takes place on a so-called gig pipe? Is it 500Mb/s or 700Mb/s? What about collisions? In other words, it may not really be a gig’s worth of bandwidth. On the other hand, as of 1997, the SMPTE 292 standard specifies sustained, real-time transfer rates of 1.5Gig HD signals as commonplace. For broadcasters, 1.5Gb/s means 1.5Gb/s."
"On the other hand, IP-based file transfers give one the freedom to route any signal anywhere. Packets can arrive out of sequence or be delayed and then be reassembled at the other end. Unfortunately, video signal transfers are intolerant of any variable delays. To improve video delivery, the IT world is moving toward switched circuits and away from routers. This is exactly the kind of composite and SDI routing that has been done for years in a broadcast infrastructure. It seems that video router methodologies are where the IT network world is finally heading."
"There may be a dozen or so essence transfers, video or audio, moving around the broadcast infrastructure at one time. How will this traffic be segmented? If file transfers are at four times real time, will it only take six hours to move a day’s worth of programming? On the negative side, one hour down means four hours of real time content lost."