TV-BAY December 2012
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To cloud, A or not to cloud? by Bob Pank lmost ever since it began, there have been two parameters that have played a big part in shaping broadcast television – bandwidth and storage. Admittedly, storage was not an issue at the start because there was no way to do it, but Ampex changed that in 1956. Bandwidth dictates many aspects of infrastructure and broadcast picture quality, the amount of space that is needed to store TV footage, and much more. Monochrome TV was relatively straightforward but colour, which originated as full bandwidth R, G and B channels was compressed by PAL or NTSC coding to fit into the bandwidth of the old monochrome channels. Today MPEG-2, MPEG- 4 (twice as good) are familiar video compression systems that typically reduce the 270 Mbits/s SD video to about 2 - 4 Mbits/s for transmission. Only just over the horizon is the latest HEVC (high efficiency video coding) that is expected to be twice as good again and will include the vast SHV – ‘8K’ format with images 16x the area of 1080 HD... and higher frame rate (HFR). All this extremely clever digital compression technology is only needed because the uncompressed video requires too much bandwidth for transmission or / and too much storage. You may ask, ‘What has this to do with the Cloud?’ The answer is ‘a whole lot’. For example if you want to have a collaborative environment for editing in the Cloud, you would first have to upload your video to the Cloud. Once there, those contributing to the edit would need to access the video to make their editing decisions. Finally, when the editing is completed, then the programme would need to be downloaded for subsequent distribution. Of course there are other ways to handle this. For example, the distribution could, theoretically be directly from the Cloud. This workflow does not mention the video format, quality requirements or any other parameters that may govern how and where the footage is handled. Nor does it say what data rates the video requires. Today there is a huge range of moving image data rates, from high definition TV to 4K digital movie material. For the TV programme the original shoot may well be compressed to 50 Mbits/s (about 23GB/hour) while the movie material would be uncompressed at something over 9000 Mbits/s (about 4200GB/hour). 26 | TV-BAY MAGAZINE TV-BAY072DEC12.indd 26 07/12/2012 15:14