VIDEO COMPRESSION & DATA RATES
Depending on the exact video codec used, the average compressed stream of HD video (720p), at 24 frames per second (fps) - and on paper, requires approximately a 10-12 megabits/second internet connection for flawless results (Wikipedia). In the real world, it's a much different story. With parity-bit checking (error checking), external internet traffic and also managing multiple connections at the home-user’s end, video streaming can quickly become very unwatchable. A sizeable overhead in the real world is very much required to successfully stream uninterrupted HD video with flawless results. So - in regards to video delivery over the internet, with the average internet connection in Australia just sitting around 10 megabits/second, Australian television consumers are sitting right on the fence between real world usability and a ‘pipe dream’ concept.
In our current landscape it is very common to see standard definition (SD) television, delivered on-demand all across the globe. 360p and 480p (once again, standard definition video) is very achievable, even within our comparably slow ADSL2+ copper networks here in Australia. SD video using MPEG2 compression (which, we have to note, isn’t the most efficient video codecs out there in the market at the moment) can deliver on-demand video at a rate of approximately 3.5 megabits/second (Wikipedia). Chris Winter (Head of Innovation at the ABC) confirms this figure and mentions that with the help of Flash (Adobe) encoding, free-to-air ABC video content delivered to Australian online television consumers can be viewed at a minimum rate of just 1.5 megabits/second - however an internet connection speed of 3 megabits/second or faster is generally recommended for maximum results. Looking aboard, it is interesting to note that the BBC have been able to offer HD content, again with the help of Adobe Flash, at a rate of 3.2 megabits/second - meaning this rate of delivery would work within Australian networks (hypothetically, if the content wasn’t ‘geoblocked’). |
Encoded with the latest craze in codecs, H264, The BBC’s iPlayer is now offering some of its content in full 720p high-definition resolution, with fairly decent 192kbps audio quality. This level of video and audio quality is extremely reasonable - and once again, with the help of Flash encoding, it can be delivered to the end-of-the-line consumer at a very reasonable data rate.
It must be mentioned, in regards to the current internet landscape within Australian networks, the ABC, our leader in free-to-air content delivery over the internet, has no real intentions of offering HD content at this point in time (Chris Winter). With the step up from SD video to HD video a rather quite considerable landmark in delivering on-demand video over the internet, consumers here in Australia might have to wait for the cost of broadband to decrease with the arrival of the NBN in the coming years. With overall internet speeds increasing in Australia, the cost of broadband per gigabyte should come down - allowing for this extra HD content to be efficiently delivered at a reasonable broadband cost. If we examine the characteristics of 480p standard definition video, we observe video dimensions of 720x480 pixels - therefore accounting for 345,600 pixels in every frame. Jumping up to 720p high definition video (the ‘lowest standard’ of high definition video), and the physical dimensions rise to 1280×720 pixels - or 921,600 pixels in each frame. Simply, to deliver this content in 720p HD, it is a jump of 2.667* times - both in terms of data throughput and also the bandwidth required to transfer this information across the internet. Once again, as the cost of broadband within Australia comes down gradually as speeds continue to slowly rise, it will soon be feasible to stream HD television content, uninterrupted within our local networks. |